Prof. Dr.-Ing. Dirk Biermann

Institut für Spanende Fertigung
TU Dortmund University

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  • Experimental and statistical analysis of the wear of diamond impregnated tools
    Malevich, N. and Müller, C.H. and Dreier, J. and Kansteiner, M. and Biermann, D. and De Pinho Ferreira, M. and Tillmann, W.
    Wear 468-469 (2021)
    Diamond impregnated tools are considered which are used to machine concrete. During their application, the bonding as well as the diamonds need to wear down in a certain way to gain a sharp tool. This required wear is called self-sharpening and means a continuous exposure of new diamonds. Within the development phase of diamond tools, time and cost intensive testing is necessary for the assessment of the tool performance. Hence, an extrapolation based on a minimal amount of testing is desirable to forecast the tool lifetime. A further reduction of the development and testing cost can be achieved by reducing the data needed to forecast the tool performance. Within this paper, the development of a statistical model is shown which was used to forecast the lifetime of the single diamonds on the tool. The statistical analysis is based on single segment tests which were carried out with different segment specification. During the tests, the exposed and broken out diamonds were counted to serve as the necessary input data for the statistical analysis. The counting of the diamonds on the segment was done in two different ways: based on the 2-dimensional microscopic pictures made after every minute of drilling and based on the 3-dimensional surface measurements made after every 5 min of drilling. It turns out that these two approaches of the wear analysis provide similar results. © 2020 Elsevier B.V.
    view abstract10.1016/j.wear.2020.203574
  • A universal pocket plunge milling method to decrease the maximum engagement angle
    Huang, N. and Krebs, E. and Baumann, J. and Wirtz, A. and Jaeger, E.M. and Biermann, D.
    Journal of Manufacturing Science and Engineering, Transactions of the ASME 142 (2020)
    Plunge milling has been proven to be an efficient strategy for machining of pockets with deep cavities and difficult-to-cut material. Previous work generates the plunge toolpath mainly by controlling the radial cutting width within the given value. However, uneven tool engagement angles may lead to excessive tool load and tool load fluctuations, which has a negative influence on tool life. In this study, a universal plunge milling toolpath generation method is proposed to improve tool life by decreasing the maximum tool engagement angle. A series of concentric circles with constant radius increment is utilized to generate a toolpath with constant cutting radial depth. Center of the concentric circle is determined based on the pocket contour. New detailed algorithms to generate plunge toolpath for basic cases have been developed. An automatic pocket subdivision algorithm has been developed by dividing the pocket into several subregions that are easy to be machined. Without loss of generality, the method is applicable for both open and closed pockets. It also works for pockets with and without islands inside. The method is implemented and verified successfully by machining experiments. The results provide strong evidence that the proposed method can reduce the maximum engagement angle over the entire toolpath and thus improve the tool life. Copyright © 2020 by ASME
    view abstract10.1115/1.4047059
  • Analysis of the functional properties in the bore sub-surface zone during BTA deep-hole drilling
    Schmidt, R. and Strodick, S. and Walther, F. and Biermann, D. and Zabel, A.
    Procedia CIRP 88 (2020)
    The BTA deep hole drilling process is analysed to determine the relationships between process-structure and residual stress as a function of surface conditioning during the machining process. The residual stresses, the hardness and structural changes in the microstructure are used as indicators for a following process control in order to generate an improved component service life or reliability. In the first tests, the deep-drilled samples are examined with regard to residual stresses, bore tolerances, microstructure and hardness in the sub-surface zone. Furthermore, the specimens will be subjected to a heat treatment to establish a stress-free microstructure as a reference state for the magnetic residual stress measurement. © 2020 The Authors.
    view abstract10.1016/j.procir.2020.05.055
  • Chip formation and phase transformation in orthogonal machining of NiTi shape memory alloy: microstructure-based modelling and experimental validation
    Kaynak, Y. and Manchiraju, S. and Jawahir, I.S. and Biermann, D.
    CIRP Annals 69 (2020)
    Phase transformation and shape memory response of NiTi alloys are sensitive to the variation of temperature and stress. Thus, the phase transformation of NiTi alloys becomes more complex during machining process. This study presents findings from a major study involving modelling of machining-induced phase transformation of NiTi alloys performed by modifying Helmholtz free energy-based microstructure model. Orthogonal cutting tests were performed to validate the predicted outputs from the simulation, such as cutting forces, temperatures and chip morphology. This work provides a strong evidence that the developed new model can accurately predict the experimentally recorded outputs in machining of NiTi alloys. © 2020
    view abstract10.1016/j.cirp.2020.04.025
  • Conduction-based thermally assisted micromilling process for cutting difficult-to-machine materials
    Platt, T. and Meijer, A. and Biermann, D.
    Journal of Manufacturing and Materials Processing 4 (2020)
    The increasing demand for complex and wear-resistant forming tools made of difficult-to-machine materials requires efficient manufacturing processes. In terms of high-strength materials; highly suitable processes such as micromilling are limited in their potential due to the increased tool loads and the resulting tool wear. This promotes hybrid manufacturing processes that offer approaches to increase the performance. In this paper; conduction-based thermally assisted micromilling using a prototype device to homogeneously heat the entire workpiece is investigated. By varying the workpiece temperature by 20 °C < TW < 500 °C; a highly durable high-speed steel (HSS) AISI M3:2 (63 HRC) and a hot-work steel (HWS) AISI H11 (53 HRC) were machined using PVD-TiAlN coated micro-end milling tools (d = 1 mm). The influence of the workpiece temperature on central process conditions; such as tool wear and achievable surface quality; are determined. As expected; the temporary thermal softening of the materials leads to a reduction in the cutting forces and; thus; in the resulting tool wear for specific configurations of the thermal assistance. While only minor effects are detected regarding the surface topography; a significant reduction in the burr height is achieved. © 2020 by the authors.
    view abstract10.3390/jmmp4020034
  • Design and optimization of energy-efficient milling processes using a geometric physically-based process simulation system
    Wirtz, A. and Biermann, D. and Wiederkehr, P.
    Procedia CIRP 88 (2020)
    The increasing complexity of production processes, shortening product lifecycles and rising energy costs lead to an emerging need for an efficiency optimization approach including process simulations in factory adaption planning as well as in process planning. This paper presents a method for the design of milling processes by analyzing process times, energy consumption and process stability based on process simulations. By evaluating simplified virtually conducted processes, reasonable parameter value combinations can be selected efficiently and provide flexibility by generating multiple solutions. Using detailed process simulations and conducting iterative adjustments to ensure a sufficient workpiece quality, the selected parameter sets are transferred to actual NC processes. © 2020 The Authors.
    view abstract10.1016/j.procir.2020.05.047
  • Disturbance of the regenerative effect by use of milling tools modified with asymmetric dynamic properties
    Baumann, J. and Wirtz, A. and Siebrecht, T. and Biermann, D.
    Journal of Manufacturing and Materials Processing 4 (2020)
    Milling processes are often limited by self-excited vibrations of the tool or workpiece, generated by the regenerative effect, especially when using long cantilevered tools or machining thin-walled workpieces. The regenerative effect arises from a periodic modulation of the uncut chip thickness within the frequencies of the eigenmodes, which results in a critical excitation in the consecutive cuts or tooth engagements. This paper presents a new approach for disturbing the regenerative effect by using milling tools which are modified with asymmetric dynamic properties. A four-fluted milling tool was modified with parallel slots in the tool shank in order to establish asymmetric dynamic characteristics or different eigenfrequencies for consecutive tooth engagements, respectively. Measurements of the frequency response functions at the tool tip showed a decrease in the eigenfrequencies as well as an increase in the dynamic compliance in the direction of the grooves. Milling experiments with a constant width of cut and constantly increasing axial depth of cut indicated a significant increase in the stability limit for the specific preparations of up to 69%.,. © 2020 by the authors.
    view abstract10.3390/jmmp4030067
  • Effect of edge preparation technologies on cutting edge properties and tool performance
    Wang, W. and Saifullah, M.K. and Aßmuth, R. and Biermann, D. and Arif, A.F.M. and Veldhuis, S.C.
    International Journal of Advanced Manufacturing Technology 106 (2020)
    Edge preparation has gained widespread use due to its low cost and high impact. Various edge preparation methods are reported in the literature. Choice of edge preparation techniques influences the edge properties and the ensuing tool performance. The current work investigates the influence of three different edge preparation methods, brushing, drag finishing, and wet abrasive jet machining on the performance of tungsten carbide inserts during orthogonal turning. Edge preparation not only changes the geometry but also the properties of the edge. Experimental results show that a drag finished edge has the lowest edge surface roughness (Ra = 0.42 μm), while abrasive jet machining can induce 63% greater compressive residual stress than the unprepared tool. Reduction in tool wear was observed at the same stage of cutting length in the prepared edges alongside improved edge hardness. A thermomechanical finite element analysis is performed to evaluate the thermomechanical behavior of all the cutting edges. Results demonstrate that the use of prepared cutting edges enhances stress distribution and reduces the temperature. Experimental results confirm that the drag finished edge has the best overall performance out of the three edge techniques with lower cutting temperature, better stress distribution, lower cutting forces, reduced flank wear, and reduced roughness of the machined surface finish. © 2019, Springer-Verlag London Ltd., part of Springer Nature.
    view abstract10.1007/s00170-019-04702-1
  • Effects on tool performance of cutting edge prepared by pressurized air wet abrasive jet machining (PAWAJM)
    Wang, W. and Biermann, D. and Aßmuth, R. and Arif, A.F.M. and Veldhuis, S.C.
    Journal of Materials Processing Technology 277 (2020)
    Edge preparation techniques are used to shape a proper edge microgeometry for enhanced tool performance. However, depending on the edge preparation method, the edge properties are also altered. Most of the reported work is limited to the effect of edge micro-geometry. In this paper, cutting edges prepared by pressurized air wet abrasive jet machining (PAWAJM) were evaluated from several aspects including tool edge geometries, tool surface quality and topographies, edge hardness (H) and residual stresses. Furthermore, the influence of the prepared edge on the tool performance of uncoated tungsten carbide cutting inserts with different average cutting edge rounding (S¯) as well as different form factor (K) were experimentally investigated through the orthogonal turning of AISI 4140 alloy steel. Results show that the performance of the prepared cutting edge depends on the combined effect of the initial state of edge geometry and edge properties For symmetric edges (form factor K = 1), the optimum range for average cutting edge rounding (S¯) was found to be 20 μm to 30 μm when using cemented carbide tools for dry machining AISI 4140 steel at a feed rate (f) =0.1 mm/rev, width of cut = 3 mm, and cutting speed (vc) = 300 m/min. © 2019 Elsevier B.V.
    view abstract10.1016/j.jmatprotec.2019.116456
  • Experimental and computational investigations on the effects of deep-temperature emulsion on the turning of Inconel 718 alloy
    Bücker, M. and De Bartolomeis, A. and Oezkaya, E. and Shokrani, A. and Biermann, D.
    CIRP Journal of Manufacturing Science and Technology 31 (2020)
    Nickel-based superalloys, for instance Inconel 718, are applied in extreme conditions due to their excellent high-temperature strength. However, the same thermomechanical properties make the machining of Inconel 718 a challenge. Cutting fluids play a vital role in extending tool life as well as preserving surface integrity. Nevertheless, their effectiveness is naturally restricted by the fluid's heat capacity. In order to improve cooling effectiveness, a new approach has been developed that combines high-pressure fluid supply and high cooling performance through the use of a deep temperature emulsion (DTE). Experimental and computational investigations were carried out on the high-speed turning of Inconel 718. Cutting forces, tool wear, chip formation and surface integrity were monitored. The experiments revealed that the addition of monoethylene glycol (MEG) reduces a cutting fluid's freezing temperature but negatively affects the machining performance. However, the observed deficiencies are compensated by the benefits of cooling the cutting fluid. The cutting fluid at a temperature of T = −10 °C leads to comparable results to those of the reference process and even to further improvements in process performance. Therefore, the application of DTE could potentially outperform and ultimately replace conventional cooling strategies. © 2020 CIRP
    view abstract10.1016/j.cirpj.2020.10.001
  • Experimental investigation on influence of engagement angle and tool geometry on plunge milling
    Huang, N. and Krebs, E. and Baumann, J. and Zhou, Y. and Wu, S. and Biermann, D.
    International Journal of Advanced Manufacturing Technology 108 (2020)
    Taking advantage of the superior cutter axial stiffness, plunge milling provides a higher material removal rate in rough milling for components with deep cavities. Tool wear depending on cutting parameters of radial cutting width, axial cutting depth, step interval, feedrate, and spindle speed has been studied by several researchers. For a more comprehensive understanding of the wear mechanism, this study investigates the influences of tool engagement angle and tool geometry on tool wear based on multiple sets of machining tests. The development of tool wear during plunge milling is monitored. Results show that tool wear of insert with large engagement angle mainly exists on minor edge, which is caused by increased tool deflection. When the radial distance equals to tool radius, optimal engagement angle can be achieved while considering both tool life and machining efficiency. The experimental results show that tool life of insert with rake angle of 22° is 6.5% higher than rake angle of 15°. Smaller corner radius has positive influences on tool life improvement. Surprisingly, tool life of insert without cutting edge chamfer is 3.6 times than insert with cutting edge chamfer. The best tool geometric parameters of plunge insert can then be identified among a variety of inserts. This work is useful for cutting tool producers and manufacturers to optimize tool geometry and machining parameters. © 2020, Springer-Verlag London Ltd., part of Springer Nature.
    view abstract10.1007/s00170-020-05480-x
  • In-process compensation of straightness deviation in BTA deep hole drilling using experimental and simulative analysis
    Gerken, J.F. and Klages, N. and Biermann, D. and Denkena, B.
    Procedia CIRP 93 (2020)
    BTA deep hole drilling is required for a variety of drilling applications with high length-to-diameter-ratios and high qualities. It is one of the latest machining operation in the production chain. Due to the high components value, high process stability and product quality is necessary. One of the most important quality features is the bore´s straightness deviation. In order to compensate this straightness deviation during the drilling process, a compensation unit has been developed. In addition, the influence of the compensation unit on the straightness deviation has been investigated in FEM simulations. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 53rd CIRP Conference on Manufacturing Systems
    view abstract10.1016/j.procir.2020.04.103
  • In-situ measurement of rake face temperatures in orthogonal cutting
    Saelzer, J. and Berger, S. and Iovkov, I. and Zabel, A. and Biermann, D., (1)
    CIRP Annals 69 (2020)
    In machining, the thermal load significantly influences the tool wear and the workpiece quality, thus limiting the productivity. Therefore, a new experimental setup for the high-speed measurement of the rake face temperature in orthogonal cutting without substantially affecting the chip formation was developed. The investigations focus on the influence of different rake face preparation methods and cutting parameters on the temperature of the rake face, measured in the immediate vicinity of the cutting edge. The presented results significantly improve the understanding of the process and provide new insights for the tool development and the validation of cutting models. © 2020 CIRP
    view abstract10.1016/j.cirp.2020.04.021
  • Influence of cutting parameters on the formation of white etching layers in BTA deep hole drilling [Einfluss der Zerspanparameter auf die Ausprägung von weißen Randschichten beim BTA Tiefbohren]
    Strodick, S. and Berteld, K. and Schmidt, R. and Biermann, D. and Zabel, A. and Walther, F.
    Technisches Messen 87 (2020)
    In this study, the influence of cutting speed and feed rate on surface integrity in Boring Trepanning Association (BTA) deep hole drilling of AISI 4140+QT is investigated. Microstructure and micro-hardness in the subsurface zones of bores are analyzed, using metallographic and micromagnetic methods. It was found that when using high feed rates and cutting speeds, white etching layers (WEL) form at the surface of the bores. These layers are up to three times harder than the substrate material and have a maximum thickness of approx. tWEL ≈ 12 μm. WEL were usually followed by a transitional layer, so that elevated hardness was observed until a depth of dsurf = 35 μm below the surface. Magnetic Barkhausen noise (MBN) analysis proved to be applicable for the fast and reliable detection of WEL. The presented results contribute to gaining a deeper understanding of the complex interrelations between the design of the BTA process, the resulting microstructure in the machined component and the properties of the conditioned surface. Based on discovered correlations, a dynamic process control will be developed for BTA deep hole drilling, which will allow reliably tailoring surface integrity of components to specific demands, like an optimized fatigue performance. © 2020 Walter de Gruyter GmbH, Berlin/Boston 2020.
    view abstract10.1515/teme-2020-0046
  • Influence of tailored surfaces and superimposed-oscillation on sheet-bulk metal forming operations
    Behrens, B.-A. and Tillmann, W. and Biermann, D. and Hübner, S. and Stangier, D. and Freiburg, D. and Meijer, A. and Koch, S. and Rosenbusch, D. and Müller, P.
    Journal of Manufacturing and Materials Processing 4 (2020)
    Producing complex sheet metal components in fewer process steps motivated the development of the innovative forming process called sheet-bulk metal forming (SBMF). In this process, sheet metal forming and bulk-metal forming are combined to create a unique forming process in which a component with external and internal gearing is produced in three production steps. However, the high degrees of deformation that occur using high-strength steels and the number of different process steps result in high process forces, strongly limiting the service life of tools. To reduce the forming force during SBMF processes, tool and process modifications were investigated. Therefore, plane-strain compression tests were conducted to examine the influence of a CrAlN PVD coating and tailored surfaces produced by high-feed milling (HF) of tool-active elements on the material flow of the specimens. In addition to the tool-sided modifications, the influence of an oscillation overlay during the forming process was investigated. Based on the results of the compression tests, the surfaces of the active tool elements of the SBMF process were modified in order to transfer the basic experimental results to the production of a functional component. The friction is thus adapted locally in the SBMF process. © 2020 by the authors.
    view abstract10.3390/jmmp4020041
  • Influence of the Feed Rate in the Single-Lip Deep Hole Drilling Process on the Surface Integrity of Steel Components
    Nickel, J. and Baak, N. and Walther, F. and Biermann, D.
    Lecture Notes in Mechanical Engineering (2020)
    High strength steels like AISI 4140 are commonly used in many technical areas in which the mechanical properties of materials have to meet special requirements, for example, in the case of dynamically loaded parts. In the automotive industry increasing requirements due to lightweight design or energy efficiency lead to increasing demands on the mechanical and dynamic material strength. In response to this development, optimized machining processes are capable of improving the mechanical properties like fatigue performance by influencing the surface integrity of the machined components. In this paper, the influence of the single-lip deep hole drilling process on the surface integrity of quenched and tempered AISI 4140 specimens is analyzed in detail. Under variation of one of the main process parameters, the feed rate, the process output parameters such as cutting forces and the resulting condition of the machined surface and subsurface are determined. In combination with the analysis of the resulting hardness, microstructure and surface conditions of the machined surface, a magnetic Barkhausen noise (MBN) analysis with a custom-built sensor is applied and further developed. With this non-destructive technique, the surface integrity of the bore wall and the fatigue damage over the lifecycle of the part can be analyzed. The correlation of the surface integrity produced by the single-lip deep hole drilling process with the results from the micro-magnetic measurements are used to improve the possibility of predicting a components fatigue performance. © 2020, Springer Nature Singapore Pte Ltd.
    view abstract10.1007/978-981-15-0054-1_21
  • Influence of the process parameters and forces on the bore sub-surface zone in BTA deep-hole drilling of AISI 4140 and AISI 304 L
    Schmidt, R. and Strodick, S. and Walther, F. and Biermann, D. and Zabel, A.
    Procedia CIRP 87 (2020)
    The relationship between the cutting speed, the feed, the resulting process forces during the BTA deep hole-drilling process and the functional properties in the bore sub-surface zone of AISI 4140 and AISI 304 L is analysed. Due to the asymmetric design of the drill head radial forces occur which are supported through guide pads on bore surface. The result is an inner force flow inside the tool that affects a self-guiding effect during the drilling process. Due to this process the bore (sub-)surface zone is impinged with thermal and mechanical loads resulting in hardening, structural changes in microstructure and the occurrence of residual stresses, which can influence the fatigue strength, service life or reliability of the part. Residual stresses are measured using the magnetic Barkhausen noise method. Understanding the relationship between the process forces and functional properties in the bore sub-surface zone is essential for a following process control in order to generate defined bore sub-surface zones. © 2020 The Author(s).
    view abstract10.1016/j.procir.2020.02.010
  • Simulative analyses focused on the changes in cutting fluid supply of twist drills with a modified flank face geometry
    Oezkaya, E. and Bücker, M. and Biermann, D.
    International Journal of Mechanical Sciences 180 (2020)
    In this paper, a combination of Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) simulations is presented. They were performed in order to develop an optimised flank face design for twist drills used for machining Inconel 718. This modification consists of a retraction behind the cutting edge which is ground into the tool flank face. It results in an increased free volume behind the cutting edge which can then be filled with cutting fluid, but in consequence, there also is a decrease in cutting material stabilising the cutting edge. Therefore, sufficient mechanical strength of the remaining cutting edge had to be ensured. At the same time, the increase in cutting fluid flow behind the cutting edge also helps to protect the remaining cutting material from the high temperatures which occur when machining nickel-based alloys such as Inconel 718. After the simulation-based findings had been transferred to real tools modified by grinding, subsequent experimental investigations could show that twist drills with a modified flank face reached tool life up to five times longer compared to standard tools. © 2020
    view abstract10.1016/j.ijmecsci.2020.105650
  • Static and oscillation superimposed ring compression tests with structured and coated tools for Sheet-Bulk Metal Forming
    Behrens, B.-A. and Meijer, A. and Stangier, D. and Hübner, S. and Biermann, D. and Tillmann, W. and Rosenbusch, D. and Müller, P.
    Journal of Manufacturing Processes 55 (2020)
    Forming tools with tailored surfaces or functional surface modifications offer great potential for the adaption and optimization of forming processes. However, the interaction of the resulting tribological conditions with additional process oscillations and lubricants has not yet been sufficiently investigated. In the field of sheet-bulk metal forming the superimposition of oscillations is a new, highly promising approach for optimizing the forming of metallic materials. The aim of this study is therefore to investigate the forming behavior of metallic materials with an oscillation superimposition in combination with structured tool surfaces. In order to examine to what extend the friction factor and the forming force can be influenced by structured surfaces and PVD-coatings ring compression tests were conducted to re-create the real process conditions. The experiments were carried out statically and with an oscillation superimposition in the main force flow of the machine under lubrication and dry conditions. Occurring interactions between surface applications, lubrication and oscillation superimposition are identified and analyzed within the context of this work. Thereby, three different deterministic surface structures of the ring compression tools were considered. A radial and tangential arrangement of a wave-like structure as well as an isotropic honeycomb structure were applied on the forming tools by means of micromilling. For a lubricated and vibration superimposed process, especially the isotropic honeycomb structure caused a significant decrease in friction. This was attributed to the formation of lubrication pockets. Despite the reduced friction, in some cases no reduction of the forming force occurred by using an oscillation superimposed forming process. This behavior was attributed to damping effects caused by the lubricating pockets. © 2020 The Society of Manufacturing Engineers
    view abstract10.1016/j.jmapro.2020.04.007
  • Study on machinability of additively manufactured and conventional titanium alloys in micro-milling process
    Hojati, F. and Daneshi, A. and Soltani, B. and Azarhoushang, B. and Biermann, D.
    Precision Engineering 62 (2020)
    Capability of Additive Manufacturing (AM) technology in the production of complex parts with high flexibility has led to the growing interest in their application as an alternative for conventional manufacturing processes. Despite the outstanding benefits of the AM process, due to their poor surface quality, the precision parts produced by this method generally need to be machined, ground, or polished. This paper addresses the machinability of AM Ti6Al4V titanium alloy parts in the micro-milling process with a specific focus on cutting forces, specific cutting energy, burr formation, and surface quality. Additive parts were produced by Electron Beam Melting (EBM) technique and were compared with the extruded Ti6Al4V parts in the micro-milling process. No significant difference could be observed in the cutting forces of both materials at chip thicknesses between 7.4 and 37.3 μm, despite the higher hardness of the EBM Ti6Al4V compared to the extruded Ti6Al4V. However, micro-milling of the EBM parts produced finer surfaces. Cutting forces and specific cutting energies of EBM parts were less than those of extruded parts at minimal chip thicknesses (lower than 7.4 μm). Continuous wavy-type burrs were formed in micro-milling of the EBM Ti6Al4V and were larger than those of extruded Ti6Al4V. © 2019 Elsevier Inc.
    view abstract10.1016/j.precisioneng.2019.11.002
  • Tribological investigation of surface structures processed by high-feed milling on HVOF sprayed WC-12Co coatings
    Tillmann, W. and Stangier, D. and Hagen, L. and Biermann, D. and Freiburg, D. and Meijer, A.
    Surface and Coatings Technology 395 (2020)
    Since properties of high-velocity oxy-fuel (HVOF) sprayed WC-12Co coatings are limited due to the inherent restrictions of the material, new approaches that involve tailored surfaces and designing friction properties of functional materials have attracted enormous interest. Within this scope, two different deterministic patterns are machined on as-sprayed and polished WC-12Co coatings by means of a high-feed milling (HFM) process, whereby different process parameters with respect to the feed per tooth as well as the lead angle are taken into account. The produced high-feed milled surfaces are investigated with respect to the resulting topography and tribological properties under dry sliding conditions. The tribological examination of the high-feed milled surfaces reveals a decreased coefficient of friction (COF) compared to the polished WC-12Co coating sliding against a 100Cr6 counter-body. The lower friction is attributed to the reduction of the contact area as well as the capability of the cavities to store the transferred material resulting from wear debris. With respect to the different surface patterns, higher values for the kurtosis Sku lead to a reduction of friction. In contrast to the results presented for 100Cr6, the WC-12Co surfaces sliding against Al2O3 counter-bodies exhibit an almost constant COF for all surfaces. Although the reduced contact area leads to increased tribological stresses, the processed surfaces show a high resistance to sliding wear. Finally, it is clarified that time- and cost-consuming mechanical surface treatments such as polishing or grinding prior to a subsequent HFM process do not have to be applied. Therefore, HFM enables a new manufacturing route to structure WC-12Co coatings as well as to modify the tribological properties. © 2020 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2020.125945
  • Tribological studies on multi-coated forming tools
    Weikert, T. and Tremmel, S. and Stangier, D. and Tillmann, W. and Krebs, E. and Biermann, D.
    Journal of Manufacturing Processes 49 (2020)
    Processes of Sheet-Bulk Metal Forming combine operations of both sheet and bulk metal forming, enabling the production of closely-toleranced functional components. Locally differing friction conditions on a single tool surface are crucial to control the material flow and to reduce process forces and tool wear. In order to understand how different friction conditions on a multi-coated tool surface affect the material flow during forming operations, variants of amorphous carbon coatings (a-C:H:W) and Cr-based hard coatings (CrAlN, CrAlCN) were deposited in combinations side by side on punches of ring compression tests. Evaluating the rings’ shapes revealed the coatings’ effects on material flow in terms of ring inner contours with sections of varying curvatures. Characteristic friction mechanisms were observed, which allowed a local delimitation of friction conditions by selectively applied coatings. © 2019 The Society of Manufacturing Engineers
    view abstract10.1016/j.jmapro.2019.11.021
  • A thermomechanical analysis leading to a novel flank face design providing longer tool lives for tools used in the drilling of Inconel 718
    Oezkaya, E. and Bücker, M. and Strodick, S. and Biermann, D.
    International Journal of Advanced Manufacturing Technology 102 (2019)
    Inconel 718 is a versatile material due to its excellent properties. However, machining and in particular drilling of Inconel 718 present great challenges for the tools. In order to increase process reliability and tool life, a novel modification for the applied drilling tools was developed. It consists of a flank face retraction behind the cutting edge which is created by grinding. While regular drilling tools feature a continuous flank face on the tool tip, the retraction provides a minimized frictional surface between the tool tip and the bore hole ground. Furthermore, computational fluid dynamics simulations have shown that the created vacuous volume behind the cutting edge becomes filled with cutting fluid during the drilling process. The described effects result in longer tool lives which could be shown in experimental investigations. This paper presents the conducted experiments in which both the occurring mechanical and thermal loads were examined in order to determine the radius-dependent thermomechanical loads along the cutting edge. The results have shown that an increase in either cutting speed or feed result in significantly higher temperatures at the cutting edge corners while temperatures at the inner diameter of the tool remained almost constant. At the same time, a rise in feed leads to notably higher mechanical loads along the whole cutting edge. In addition, reference tool life tests were conducted using standard tools and under variation of the cutting values. The resulting tool wear as well as the tool-workpiece contact zones were investigated in detail. The gathered findings were then used to develop a flank face modification whose sufficient thermomechanical stability was ensured by FEM simulations. Afterwards, the new tool design was applied to drilling tools and then validated in field tests. The results show that a considerably higher drilling distance as well as lower tool wear and thus a longer tool life could be achieved with the modified drills. © 2019, Springer-Verlag London Ltd., part of Springer Nature.
    view abstract10.1007/s00170-019-03417-7
  • Adaption of tool surface for sheet-bulk metal forming by means of pressurized air wet abrasive jet machining
    Freiburg, D. and Aßmuth, R. and Garcia Carballo, R. and Biermann, D. and Henneberg, J. and Merklein, M.
    Production Engineering 13 (2019)
    Surface structures are used for several applications in industry to enhance the characteristics of surfaces and therefore processes. One example is the Sheet-bulk metal forming process which combines the advantages of bulk and sheet metal forming. Due to the complex material flow and load, the tool surfaces do need adapted tribological properties. High feed milled surface structures have been used in the past to control the material flow of the sheets. But due the high stresses appearing, the surfaces show a running-in behavior which altereds the tribological conditions. Within this study, a pressurized air wet abrasive jet machining (PAWAJM) process is used for adapting the high feed milled surface in order to manipulate the tribological conditions. Therefore, the surfaces characteristics, residual stresses as well as the tribological effects were investigated. It is shown that the PAWAJM process can be used to modify the surface characteristics and thus the friction of the surface. In addition, it can be seen that residual compressive stresses are applied during the PAWAJM. © 2018, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-018-0858-4
  • Analysis of contour accuracy and process forces using a chamber-boring-system
    Schmidt, R. and Gerken, J.F. and Fuß, M. and Biermann, D.
    MM Science Journal 2019 (2019)
    Deep hole drilling is a metal cutting method for producing primary cylindrical deep bores with a length-to-diameter ratio larger than l/D = 10. Due to the increasing interest of different branches of the industry in inner contoured workpieces, the Institute of Machining Technology (ISF) and the BGTB GmbH developed a chamber boring system, which allows to contour boreholes in axial and radial directions. This paper presents the influence of different cutting speeds, feeds and workpiece materials on the contour accuracy and the mechanical tool loading. © 2019, MM publishing Ltd.. All rights reserved.
    view abstract10.17973/MMSJ.2019_11_2019087
  • Analytical and simulation-based prediction of surface roughness for micromilling hardened HSS
    Meijer, A. and Bergmann, J.A. and Krebs, E. and Biermann, D. and Wiederkehr, P.
    Journal of Manufacturing and Materials Processing 3 (2019)
    The high quality demand for machined functional surfaces of forming tools, entail extensive investigations for the adjustment of the manufacturing process. Since the surface quality depends on a multitude of influencing factors in face micromilling, a complex optimization problem arises. Through analytical and simulative approaches, the scope of the experimental investigation to meet the requirements for surface roughness can be significantly reduced. In this contribution, both analytical and simulation-based approaches are presented in the context of predicting the roughness of a machined surface. The consideration of actual tool geometry and shape deviations are used in a simulation system to achieve the agreement with experimental results. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
    view abstract10.3390/jmmp3030070
  • Barkhausen noise-based fatigue life prediction of deep drilled AISI 4140
    Baak, N. and Nickel, J. and Biermann, D. and Walther, F.
    Procedia Structural Integrity 18 (2019)
    High-strength steels like AISI 4140 are commonly used for high dynamically loaded parts. Increasing demands for lightweight parts with higher performance and efficiency in automotive industry claim improving material properties. An optimised drilling process should enhance the fatigue life of deep-drilled components by the induction of residual stresses in the borehole, without the need for expensive additional processing steps, e.g. autofrettage. Non-destructive testing techniques like magnetic Barkhausen noise analysis offer quick and reliable possibilities to detect and classify material parameters like hardness and residual stresses. The aim of this study is to evaluate and extrapolate the resulting fatigue performance of deep drilled round specimens due to drilling parameters at an early stage of fatigue life. It was shown, that the coercive field strength decreases approximately linear with proceeding fatigue damage. The slope of the degradation coefficient is comparable for different surface layer conditions. This leads to the assumption that the variation of the micromagnetic parameters is caused by fatigue-induced microstructural changes. Therefore, a microstructure-based prediction of the fatigue life by means of micromagnetic measurements can be established. © 2019 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.prostr.2019.08.164
  • Chatter avoidance in milling by using advanced cutting tools with structured functional surfaces
    Baumann, J. and Krebs, E. and Biermann, D.
    MM Science Journal 2019 (2019)
    The productivity of machining processes is often limited by the occurrence of dynamic effects. The presented approach intends to counteract tool deflections, and thus to damp and disrupt chatter vibrations by using milling tools with defined functional structures on the flank faces at the minor cutting edges. The potential of process stabilization is evaluated by analyzing the operational behavior of three variants of surface structures in experiments, in which an aluminum alloy was machined. An increase of the process stability and productivity of up to 60 % could be achieved. © 2019, MM publishing Ltd.. All rights reserved.
    view abstract10.17973/MMSJ.2019_11_2019045
  • Developments in pre- and post-treatment of thin films and their influences on surface topography and coating adhesion strength of cutting tools
    Bathe, T. and Biermann, D.
    Production Engineering 13 (2019)
    Due to the increased requirements on machining of metallic and non-metallic materials, the pre- and post-treatment of hard thin films has been an important topic in several researches in the past decade. The main improvement in tool properties by a reduction of surface inhomogeneities is reached by an additional mechanical or chemical treatment before and/or after the coating process. Especially the cleaning before coating has to be considered to reduce the amount of debris of the pre-treatment which may negatively effect surface quality after the coating process. The mainly used processes of mechanical treatment to enhance surface topography before and after coating are several machining processes such as abrasive jet machining or drag finishing. This paper introduces a novel process for the pre- and post-treatment of coated cutting tools by elastically bonded diamond grinding wheels. Both the removal rate of surface inhomogeneities, the influence of surface topography before and after coating and the influence of the initial tool surfaces regarding coating adhesion strength were investigated to underline the potential of this pre- and post-treatment. Additionally, a new method for characterizing and describing the number of coating defects and proportion area of coating defects per mm 2 is presented. © 2019, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-019-00921-3
  • Evaluation of cutting processes using geometric physically-based process simulations in view of the electric power consumption of machine tools
    Wirtz, A. and Meißner, M. and Wiederkehr, P. and Biermann, D. and Myrzik, J.
    Procedia CIRP 79 (2019)
    Dynamic customer demands require efficient and effective adaptations of factory systems and processes. Due to rising energy prices and consumption in manufacturing industries, energy efficiency is increasingly respected during adaptation planning. An empirical model of the power consumption of machine tools is validated and combined with a geometric physically-based process simulation. The model is experimentally validated and applied to selected processes for analyzing the effect of chatter on the power consumption. An approach for an application within the factory adaptation planning is presented giving the opportunity to simulate and optimize milling processes in order to support planning processes. © 2019 The Author(s).
    view abstract10.1016/j.procir.2019.02.083
  • Examination of the Material Removal of unreinforced, thermoplastic Polymers by Scratch Tests
    Kamplade, K. and Biermann, D.
    Production Engineering 13 (2019)
    The use of plastics in the industry is steadily growing. Based on the material characteristics, such as low weight, conventional materials like steel are being replaced. For that reason, plastic components need to be machined to fulfill requirements regarding size shape and surface quality. Grinding processes are used to achieve high surface quality and dimensional and shape accuracy. The following article deals with scratch tests to basically analyse the grain engagement when grinding thermoplastics. For this, corundum grains are used in two different scratch test setups for fundamental analysis of the material removal process. The scratching process is evaluated by the relative chip volumes of the scratch grooves. In addition to that, the forces occuring during the process and the required specific scratch energy are analysed. © 2019, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-019-00925-z
  • Fluid structure interaction (FSI) modelling of deep hole twist drilling with internal cutting fluid supply
    Oezkaya, E. and Iovkov, I. and Biermann, D.
    CIRP Annals 68 (2019)
    This paper presents a novel approach for coupling of thermal FE and CFD simulations to predict the temperature distribution in the cutting process. The developed FSI model considers experimentally validated workpiece temperature to simulate the heat convection interactions in drilling operations. This innovative method allows not only for the common analysis of the flow behaviour, but additionally for the detailed investigation of the temperature distribution within the cutting fluid. The simulation provides indications for an insufficient fluid supply of the cutting edge and the results can contribute significantly to the further optimisation of thermally high stressed cutting tools and processes. © 2019
    view abstract10.1016/j.cirp.2019.03.003
  • Influence of the diamond grain shape and orientation on the process forces and the mechanical work in scratch tests on basalt stone
    Kansteiner, M. and Biermann, D.
    Diamond and Related Materials 94 (2019)
    For the machining of stone like basalt, granite, marble or limestone, but also for concrete, brickwork etc. mainly diamond impregnated tools are used. Due to new possibilities regarding the production of diamond impregnated tools, but also regarding diamond synthesis, it is likely that for further improvements in the performance of diamond impregnated tools, the shape of the single grains becomes increasingly important. When machining stone or concrete with diamond impregnated tools, several diamond grains penetrate the material and generate the material removal. A simplified method for the analysis of grinding processes is the single grain scratch test. This approach is widely used to understand the fundamental mechanisms at a single grain engagement. Within this paper, results are presented and discussed, which are gained in scratch tests on basalt stone. Its focus is the analysis of the influence of the grain shape on the process forces and the mechanical work. It can be assumed that different grain shape cause different material removal mechanisms. In order to analyze this influence tests with three different diamond grains and varying process parameters (cutting speed and feed speed) were conducted. The process results strongly indicate that a diamond grain with a leading edge is advantageous regarding the material removal mechanism of basalt stone. © 2019 Elsevier B.V.
    view abstract10.1016/j.diamond.2019.02.027
  • Investigating the impact of tool inertia on machinability of a β-titanium alloy using tool deflection and acoustic emission
    Iqbal, A. and Biermann, D. and Ali, H.M. and Zaini, J. and Metzger, M.
    Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233 (2019)
    Finding sustainable ways of machining exotic materials is gaining more and more importance in the manufacturing industry. Application of advanced measuring instruments for quantifying performance measures is a crucial requirement for making machining processes viable. The presented work aims to ameliorate machining of a high-strength β-titanium alloy using information from measurements of key responses, such as cutting energy consumption, tool deflection, and tool damage. Acoustic emission data and tool’s acceleration data are utilized to work out the magnitudes of energy consumed and deflection undergone by the tool, respectively. The article focuses on quantifying the effects of tool’s inertia, strength of work material, and two cutting parameters on the aforementioned responses. A total of 54 continuous cutting experiments are performed in which a fixed volume of material per experimental run is removed. Tool deflection method helped to determine the significant effects of varying tool inertia, work material strength, and cutting speed on the machining process. Likewise, acoustic emission method highlighted the strong effects of material strength and cutting speed caused on the cutting energy consumption. The effect of feed rate is found to be significant regarding tool wear only. Finally, the tool wear data are tested for correlation against the corresponding data sets of the other two responses. It is found that both tool deflection and cutting energy possess strong uphill relationships with tool wear. © IMechE 2018.
    view abstract10.1177/0954405418802319
  • Investigation on cutting edge preparation and FEM assisted optimization of the cutting edge micro shape for machining of nickel-base alloy
    Tiffe, M. and Aßmuth, R. and Saelzer, J. and Biermann, D.
    Production Engineering 13 (2019)
    The productivity and the tool life of cutting tools are majorly influenced by the cutting edge micro shape. The identification of optimized cutting edges is usually based on empirical knowledge or is carried out in iterative investigation steps. This paper presents an approach to predict optimal cutting edge micro shapes with the aid of finite-element-simulations of the chip formation. The approach is investigated for the machining of the nickel-base alloy Inconel 718. The cutting edges are prepared by pressurized air wet abrasive jet machining. Utilizing this method, the prepared cutting edges have a certain profile, which is considered for the modelling. By applying a model for tool wear the influence of the cutting edge micro shape on the tool life span is estimated. Subsequently, a statistical modelling provides the prediction of the tool wear rate for any possible parameter set within the investigated range. This is used to find an optimized cutting edge profile that minimizes the tool wear. An experimental investigation concludes the optimization procedure. © 2019, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-019-00900-8
  • Micromagnetic-based fatigue life prediction of single-lip deep drilled AISI 4140
    Baak, N. and Nickel, J. and Biermann, D. and Walther, F.
    Structural Integrity 7 (2019)
    Non-destructive testing based on micromagnetic techniques, for example magnetic Barkhausen noise analysis, are quick and reliable possibilities to detect and classify material parameters like hardness and residual stresses. High-strength steels, like AISI 4140 (42CrMo4 + QT), are commonly used for highly dynamically loaded parts. Increasing requirements on weight, performance and efficiency of automotive industry claim increasing demands on material properties. The aim of this study is to evaluate the surface conditions of deep drilled round specimens due to drilling parameters and to predict the resulting fatigue strength by micromagnetic measurements. Furthermore, modified process parameters should enhance fatigue life without the need for expensive processing steps, e.g. autofrettage. © Springer Nature Switzerland AG 2019.
    view abstract10.1007/978-3-030-13980-3_3
  • Microstructural characteristics of high-feed milled HVOF sprayed WC-Co coatings
    Tillmann, W. and Hagen, L. and Stangier, D. and Paulus, M. and Tolan, M. and Sakrowski, R. and Biermann, D. and Freiburg, D.
    Surface and Coatings Technology 374 (2019)
    Over the last decade, great efforts have been undertaken in science and industry to provide WC-Co feedstock with nano-sized WC particles that significantly improves tribo-mechanical coating properties. For tribologically stressed surfaces, superior surface characteristics can be achieved by applying tailored surfaces, using novel technologies in the field of production engineering such as High-Feed Milling (HFM). For the first time, textured surface patterns were produced onto HVOF sprayed WC-Co coatings with nano-sized WC particles by implementing a HFM post process. In dependence to two different textures resulting from the HFM, the microstructural characteristics of the produced surfaces are analyzed. Confocal microscopy revealed the machinability of textured patterns onto a HVOF-sprayed WC-12Co hard coating, which comprise of nano-sized WC particles, by means of HFM technology. X-ray diffraction analyses confirmed the insertion of macro- and micro-scale residual stresses. The experiments showed a significant insertion of compressive residual stresses transverse to the feed direction, whereas the insertion of compresses residual stresses with its feed direction being less pronounced. It was found that the HFM post process leads to a refinement of the WC crystallite size and a distinct increase of its internal strain, which both can be attributed to plastic deformations during HFM. © 2019 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2019.06.012
  • Multi-level simulation concept for multidisciplinary analysis and optimization of production systems
    Delbrügger, T. and Meißner, M. and Wirtz, A. and Biermann, D. and Myrzik, J. and Rossmann, J. and Wiederkehr, P.
    International Journal of Advanced Manufacturing Technology 103 (2019)
    In the context of digitization and industry 4.0, the production-related disciplines developed powerful simulation models with different scopes and varying levels of detail. As these simulation systems are usually not built in a compatible way, the models cannot be combined easily. Co-simulation techniques provide a promising basis for combining these models into one superordinate model and utilizing it for planning new factories, adapting existing ones or for production planning. However, today’s co-simulation systems do not benefit from the inherent flexibility of the represented production systems. Simulation-based optimization is carried out inside each discipline’s simulation system, which means that interdisciplinary, global optima are often impossible to reach. Additionally, the aspect of human interaction with such complex co-simulation systems is often disregarded. Addressing these two issues, this paper presents a concept for combining different simulation models to interdisciplinary multi-level simulations of production systems. In this concept, the inherent flexibilities are capitalized to enhance the flexibility and performance of production systems. The concept includes three hierarchical levels of production systems and allows human interaction with the simulation system. These three levels are the Process Simulation level, the Factory Simulation level, and the Human Interaction level, but the concept is easily extendable to support additional levels. Within the multi-level structure, each simulation system carries out a multi-objective optimization. Pareto-optimal solutions are forwarded to simulations on higher hierarchical levels in order to combine them and meet flexibly adaptable objectives of the entire production system. The concept is tested by means of a simplified production system, to optimize it in terms of throughput time and electric energy consumption. Results show that the presented interdisciplinary combination of heterogeneous simulation models in multi-level simulations has the potential to optimize the productivity and efficiency of production systems. © 2019, Springer-Verlag London Ltd., part of Springer Nature.
    view abstract10.1007/s00170-019-03722-1
  • Reduction of ejection forces in injection molding by applying mechanically post-treated CrN and CrAln PVD films
    Tillmann, W. and Stangier, D. and Lopes Dias, N.F. and Gelinski, N. and Stanko, M. and Stommel, M. and Krebs, E. and Biermann, D.
    Journal of Manufacturing and Materials Processing 3 (2019)
    In injection molding, the reduction of ejection forces is a process relevant aspect to improve the production rates. For this purpose, CrN and CrAlN films were sputtered on cylindrical and quadratic AISI H11 cores of an injection mold in order to investigate their influence on the resulting ejection forces to demold polypropylene test components. Within this context, the ejection forces of the PVD coated cores were compared to those of uncoated cores made of AISI H11. For both the cylindrical and quadratic cores, the as-deposited CrN and CrAlN films exhibit higher ejection forces than the uncoated cores due to the increase of the roughness profile after sputtering. It is known that the ejection forces are directly related to the surface roughness. In order to ensure comparable surface conditions to the uncoated surfaces, and to demonstrate the potential of PVD coated mold surfaces when reducing the ejection forces, the coated surfaces were mechanically post-treated to obtain a similar roughness profile as the uncoated cores. The combination of a PVD deposition and post-treatment ensures a significant reduction of the ejection forces by 22.6% and 23.7% for both core geometries. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
    view abstract10.3390/jmmp3040088
  • Statistical Analysis of the Lifetime of Diamond-Impregnated Tools for Core Drilling of Concrete
    Malevich, N. and Müller, C.H. and Kansteiner, M. and Biermann, D. and Ferreira, M. and Tillmann, W.
    Studies in Classification, Data Analysis, and Knowledge Organization (2019)
    The lifetime of diamond-impregnated tools for core drilling of concrete is studied via the lifetimes of the single diamonds on the tool. Thereby, the number of visible and active diamonds on the tool surface is determined by microscopical inspections of the tool at given points in time. This leads to interval-censored lifetime data if only the diamonds visible at the beginning are considered. If also the lifetimes of diamonds appearing during the drilling process are included, then the lifetimes are doubly interval-censored. We use a well-known maximum likelihood method to analyze the interval-censored data and derive a new extension of it for the analysis of the doubly interval-censored data. The methods are applied to three series of experiments which differ in the size of the diamonds and the type of concrete. It turns out that the lifetimes of small diamonds used for drilling into conventional concrete are much shorter than the lifetimes when using large diamonds or high-strength concrete. © Springer Nature Switzerland AG 2019.
    view abstract10.1007/978-3-030-25147-5_15
  • Surface structuring using multi-stage grinding strategies based on geometric physically-based process simulations
    Siebrecht, T. and Potthoff, N. and Wiederkehr, P. and Biermann, D.
    Procedia Manufacturing 29 (2019)
    For various industrial applications, e.g., the manufacturing of forming tools for the automotive sector, surface structures of functional areas play a decisive role. NC grinding processes on machining centers represent a flexible solution for finishing the free-form surfaces of forming tools. However, the surface topographies are influenced by several factors like the distribution of the grains and the wear of the tools. In this paper, a geometric physically-based simulation system is applied to predict the surface structures for different multi-stage grinding strategies. Point clouds were used for modeling the individual grains, which allows the simulation of different states of tool wear and the resulting influence on the surface topographies and process forces. Due to the high number of grains on the grinding tools, a stochastic model for the grain distributions and a database of different grain shapes were created based on representative measurements. The simulated surfaces are compared to experimental results in order to validate this approach. © 2019 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.promfg.2019.02.095
  • The effect of machined surface conditioning on the coating interface of high velocity oxygen fuel (HVOF) sprayed coating
    Tilger, M. and Biermann, D. and Abdulgader, M. and Tillmann, W.
    Journal of Manufacturing and Materials Processing 3 (2019)
    Roughening the substrate surface is essential for thermal sprayed coatings. In this regard, sandblasting has established itself as an easy to use surface conditioning procedure. The quality of the obtained roughness depends on the conditions of the sandblasting material, adjusted parameters, and the kind of the process execution (manual or mechanical). These preconditions limit the reproducibility of the roughness obtained. Sandblasting causes residual compressive stress and may also lead to the inclusion of sand particles and notches in the roughened surface, which affects the interfacial properties of the coating, as well as the flexural strength of the coated parts. The hardness of the roughened surface plays, thereby, an important role. However, in order to reliably avoid these effects, microfinishing can be used as an alternative to generate a homogenous roughened substrate surface, control the induced residual stresses, and increase the reproducibility. In addition, the roughened surface pattern can be produced during the chip forming process of the to-be-coated parts. The utilization of the appropriate combination of machining processes and parameters should lead to the required surface pattern and thus to an enhanced coating adhesion and flexural strength of the coated part. The induced residual stresses and the quality of the obtained surface roughness have a significant influence on the coating adhesion and the lifespan of the coated parts. This paper aims to analyze, as a first step, the effect of the turning and microfinishing on the surface conditioning of the bearing steel 100Cr6 (AISI 52100). The investigation concludes by comparing the microfinished with the sandblasted surfaces with regard to the interface to and the adhesion of the WC–Co high velocity oxygen fuel (HVOF) sprayed coatings on them. Surface conditioning plays a decisive role by the induced residual stresses and the elimination of adhesion defects. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
    view abstract10.3390/jmmp3030079
  • The effect of runout errors on process forces and tool wear
    Baumann, J. and Siebrecht, T. and Wiederkehr, P. and Biermann, D.
    Procedia CIRP 79 (2019)
    The runout of milling tools results in uneven effective tooth radii and affects the occurrence of tool wear in machining processes. The load and, thus, the specific wear of teeth with increased effective radii is higher. In processes with small undeformed chip thicknesses, e.g., the finishing of titanium alloys, the runout error could even be greater than the undeformed chip thickness. In this case, at least one cutting edge does not remove any material. In this paper, the influence of the runout on wear effects is analyzed for an exemplary finishing process using cutting force measurements and a geometric physically-based process simulation. © 2019 The Author(s).
    view abstract10.1016/j.procir.2019.02.008
  • Vibration suppression in turning TiAl6V4 using additively manufactured tool holders with specially structured, particle filled hollow elements
    Vogel, F.A.M. and Berger, S. and Özkaya, E. and Biermann, D.
    Procedia Manufacturing 40 (2019)
    As a result of the material-specific segmented chip formation occurring during the machining of titanium alloys, the tools used can be set into vibration significantly depending on the given process conditions. In addition to an increased tool wear, this often leads to not being able to achieve the required workpiece qualities. With the use of additively manufactured tool holders for turning TiAl6V4, a passive damping of such chip-induced tool vibrations can be realised. The decisive factor is the production of specially structured hollow elements in the tool holder shafts, which can be realised by the additive manufacturing process. The tools' vibration amplitudes were significantly reduced on the one hand due to the resulting vibration-optimised tool design, and on the other hand due to the internal friction of additional filling materials applied into the shafts hollow elements. © 2019 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.promfg.2020.02.007
  • A new reverse engineering method to combine FEM and CFD simulation three-dimensional insight into the chipping zone during the drilling of Inconel 718 with internal cooling
    Oezkaya, E. and Biermann, D.
    Machining Science and Technology (2018)
    The use of cooling lubricants in metal machining increases both the tool life and the quality of workpieces and improves the overall sustainability of production systems. In addition to fulfilling these main functions, the focus of machining processes is also related to the reduction of environmental pollution. This can for example be achieved by an optimized arrangement of the cutting tool cooling channels. Therefore, the active cutting edges of the tool should be effectively supplied with a sufficient amount of cooling lubricant. An analysis of the tribological stress is rather difficult because the complex contact zone is inaccessible. Hence, optical investigations are often limited to only observing the chip formation or analyzing the process without considering the influence of the chips. This article presents an innovative method, which enables a deeper three-dimensional insight into the chip formation zone during drilling with internal cooling channels, considering the cooling lubricant distribution and chip formation. The chip formation simulation based on the finite element method and the computational fluid dynamics flow simulation are combined. In this way, the differences between the different geometric models that do not allow any joint generation of numerical information due to missing interfaces are overcome. © 2018 Taylor & Francis Group, LLC
    view abstract10.1080/10910344.2017.1415933
  • Analysis of the laser drilling process for pilot holes in complex shaped components
    Michel, S. and Biermann, D.
    Procedia CIRP 74 (2018)
    In contrast to mechanical drilling, laser drilling can be applied directly to complex surfaces. The laser holes can thereby serve as pilot holes for mechanical deep hole drilling to produce high quality bore holes. This article examines the influence of pulse power, pulse duration and focus distance on the laser drilling process for curved surfaces using a Nd:YAG-Laser for the stainless steel X2CrNiMo17-12-2 and the case hardening steel 20MnCr5. By varying the laser parameters holes were produced that met the requirements for pilot holes in terms of diameter tolerances, drilling depth, conicity and material influences to enable the process combination. © 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
    view abstract10.1016/j.procir.2018.08.156
  • Barkhausen noise assessment of the surface conditions due to deep hole drilling and their influence on the fatigue behaviour of AISI 4140
    Baak, N. and Schaldach, F. and Nickel, J. and Biermann, D. and Walther, F.
    Metals 8 (2018)
    In many technical fields, high-strength steels like AISI 4140 are commonly used for highly dynamically loaded parts. Increasing demands on weight, performance and efficiency of the automotive industry lead to increasing demands on material properties. For surface conditioning, optimised machining processes are capable of improving the fatigue performance without increasing the production cost significantly. This paper compares the influence of three different sulphur contents and three different feed rates on the fatigue behaviour of deep hole drilled AISI 4140 fatigue specimens. The specimens were characterised regarding their surface condition, hardness and microstructure, and afterwards they were tested under fatigue loading for performance assessment. These tests were accompanied with Barkhausen noise analysis. The Barkhausen noise signal was detected by a custom-built sensor that is capable of detecting the magnetic values on the bore wall. Using this technique, a load-independent estimation of fatigue damage was established. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.
    view abstract10.3390/met8090720
  • Control of the material flow in sheet-bulk metal forming using modifications of the tool surface
    Löffler, M. and Schulte, R. and Freiburg, D. and Biermann, D. and Stangier, D. and Tillmann, W. and Merklein, M.
    International Journal of Material Forming (2018)
    Sheet-bulk metal forming (SBMF) processes are characterized by a successive and/or simultaneous occurrence of different load conditions such as the stress and strain states. These conditions influence the material flow and often lead to a reduced geometrical accuracy of the produced components. To improve the product quality, a control of the material flow is required. One suitable approach, the local adaption of tribological conditions by means of surface modifications of tool or workpiece, so-called tailored surfaces. To control the material flow and thus to improve the component accuracy, methods to reduce and to increase friction are needed. The aim of this study is to determine requirements for necessary adaptions of the friction, the identification of tribological mechanisms for different types of tool-sided tailored surfaces as well as the verification of the effectiveness of these surface modifications to improve the results of a specific SBMF process. The numerical analysis of a combined deep drawing and upsetting process revealed that this process is characterized by two areas of varying tribological load conditions. Using a numerical analysis, the friction factor gradient between these two areas was identified as a main influencing factor on the material flow. Based on this finding, Chromium-based hard coatings for the reduction of the friction and high-feed milled surfaces for an increase of the friction were investigated regarding their frictional behaviour. The results of the ring-compression tests revealed that the carbon content and the post treatment of coated tool surfaces are relevant to reduce the friction. The increased profile depth of the milled surfaces was identified as the main influencing factor on the tribological behaviour of this kind of tailored surfaces. The effectiveness of both types of tailored surfaces was verified for the combined deep drawing and upsetting process. © 2018 Springer-Verlag France SAS, part of Springer Nature
    view abstract10.1007/s12289-018-1399-2
  • Development of a geometrical torque prediction method (GTPM) to automatically determine the relative torque for different tapping tools and diameters
    Oezkaya, E. and Biermann, D.
    International Journal of Advanced Manufacturing Technology 97 (2018)
    This research paper presents the development of a geometrical torque prediction method (GTPM), which could be used to determine relative torque values for tapping processes with various tapping tools and diameters. Experimental tests and three-dimensional finite element method (FEM) simulations were carried out using four different tap tools that are frequently used in practice. A segmented workpiece model, which could significantly reduce the computing time of the FEM tapping simulations, was validated by comparing the results to the experimentally obtained data. The determined relative torque values show a parabolic progression with rising tool diameter, which is the reason why the GTPM could be developed on this basis, to further reduce the high computing time and optimize the tool design process without the production of costly prototypes. To verify the developed GTPM, the according predicted relative torque values were compared to the previously carried out simulations and experiments, showing a good agreement. A FEM software module was created to implement the developed methods in an interactive and automated way, providing an efficient method to improve the tapping tool development process. © 2018, Springer-Verlag London Ltd., part of Springer Nature.
    view abstract10.1007/s00170-018-2037-3
  • Development of a three-dimensional finite element method simulation model to predict modified flow drilling tool performance
    Oezkaya, E. and Hannich, S. and Biermann, D.
    International Journal of Material Forming (2018)
    Flow drilling is a relatively unexplored manufacturing process in which the tool penetrates the workpiece with a defined force or defined feed along its rotational axis. This paper presents a developed three-dimensional (3D)-finite element method (FEM) simulation model to predict the performance of modified flow drilling tools. To validate the simulation model, the flow drilling of AlSi10Mg with a non-pre-heated (Tinitial = 20 °C) and pre-heated (Tinfluenced = 200 °C) tool was investigated. Thereby, the comparison of measured and simulated values of temperature, force and torques showed a good agreement. The comparison of the forces and torques concluded in almost identical maximum values. Nevertheless, the pre-heated tool was found to have a significantly more continuous heat distribution and higher bore quality than non-pre-heated flow drills, which can be attributed to the better formability of the cast aluminum alloy at elevated temperatures. Since the results of the simulation showed a good agreement with the experimental values, the three-dimensional model was used to predict the process behavior of a modified flow drilling tool, which could contribute to the optimization of the process. The result show, that the process time could be reduced by half, while the occurring temperatures, forces and torques remained acceptable. © 2018, Springer-Verlag France SAS, part of Springer Nature.
    view abstract10.1007/s12289-018-1429-0
  • Influence of the deep hole drilling process and sulphur content on the fatigue strength of AISI 4140 steel components
    Nickel, J. and Baak, N. and Biermann, D. and Walther, F.
    Procedia CIRP 71 (2018)
    When using quenched and tempered steels in the automotive industry or other industrial applications the fatigue behavior is of elementary importance. The surface and subsurface integrity of machined parts is known as one key factor related to the fatigue strength of components and is strongly influenced by the machining process. Especially for the deep hole single lip drilling, a large part of the cutting force is transferred to the bore wall and the surface and subsurface zone are influenced by the interaction between the tool and the workpiece material. In this study, the approach of inserting residual stresses into the bore wall and influencing the microstructure of the bores subsurface in a way, that the components can withstand a higher mechanical and dynamic load, is investigated in detail. In a close cooperation between the authors the parameters of the single-lip drilling process and the workpiece material are correlated with the produced surface quality and subsurface microstructure as well as the resulting fatigue strength of the components. For the comparative characterization of the fatigue behavior, established test procedures of destructive material testing in combination with new non-destructive test methods, such as the Barkhausen noise analysis, are applied and developed further. The results of the fatigue tests in correlation with the results of the Barkhausen noise analysis are used to design a model for predicting the fatigue strength of drilled components. © 2018 Elsevier B.V. All rights reserved.
    view abstract10.1016/j.procir.2018.05.069
  • Machining β-titanium alloy under carbon dioxide snow and micro-lubrication: a study on tool deflection, energy consumption, and tool damage
    Iqbal, A. and Biermann, D. and Abbas, H. and Al-Ghamdi, K.A. and Metzger, M.
    International Journal of Advanced Manufacturing Technology (2018)
    The alloys of the beta allotropic form of titanium are among the most difficult-to-cut materials. An extremely poor machinability calls for special ways of performing machining with an emphasis on developing new methods of heat dissipation. The paper focuses on evaluating effectiveness of using CO2 snow as a coolant in continuous machining of a β-titanium alloy. It also explores the most appropriate location of its application in the cutting area and usefulness of its hybridization with minimum quantity of lubrication. The effectiveness of using the two cutting fluids is compared with an emulsion-based flood coolant. The effects of varying work material’s yield strength and cutting speed are also investigated. The measured responses include tool displacement area (a measure of tool deflection obtained from tool acceleration data), cutting energy consumed (obtained from acoustic emissions data), and tool wear. The results show that the usage of CO2 snow and its location of application possess a significant effect on the responses. The combination of CO2 snow and minimum quantity of lubrication is found to be the most effective way of heat dissipation and lubrication. With regard to tool damage, the scanning electron microscopy shows the presence of gradual wear and cutting speed-dependent adhesion but no evidence of chipping. The paper also presents a possibility of estimating tool damage condition through acoustic emission and tool deflection data. In this regard, a strong uphill relationship between tool wear and cutting energy is observed. © 2018 Springer-Verlag London Ltd., part of Springer Nature
    view abstract10.1007/s00170-018-2267-4
  • Micro-magnetic and microstructural characterization of wear progress on case-hardened 16MnCr5 gear wheels
    Knyazeva, M. and Vasquez, J.R. and Gondecki, L. and Weibring, M. and Pöhl, F. and Kipp, M. and Tenberge, P. and Theisen, W. and Walther, F. and Biermann, D.
    Materials 11 (2018)
    The evaluation of wear progress of gear tooth flanks made of 16MnCr5 was performed using non-destructive micro-magnetic testing, specifically Barkhausen noise (BN) and incremental permeability (IP). Based on the physical interaction of the microstructure with the magnetic field, the micro-magnetic characterization allowed the analysis of changes of microstructure caused by wear, including phase transformation and development of residual stresses. Due to wide parameter variation and application of bandpass filter frequencies of micro-magnetic signals, it was possible to indicate and separate the main damage mechanisms considering the wear development. It could be shown that the maximum amplitude of BN correlates directly with the profile form deviation and increases with the progress of wear. Surface investigations via optical and scanning electron microscopy indicated strong surface fatigue wear with micro-pitting and micro-cracks, evident in cross-section after 3 × 105 cycles. The result of fatigue on the surface layer was the decrease of residual compression stresses, which was indicated by means of coercivity by BN-analysis. The different topographies of the surfaces, characterized via confocal white light microscopy, were also reflected in maximum BN-amplitude. Using complementary microscopic characterization in the cross-section, a strong correlation between micro-magnetic parameters and microstructure was confirmed and wear progress was characterized in dependence of depth under the wear surface. The phase transformation of retained austenite into martensite according to wear development, measured by means of X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) was also detected by micro-magnetic testing by IP-analysis. © 2018 by the authors.
    view abstract10.3390/ma11112290
  • Modeling the motion of the cooling lubricant in drilling processes using the finite volume and the smoothed particle hydrodynamics methods
    Schnabel, D. and Özkaya, E. and Biermann, D. and Eberhard, P.
    Computer Methods in Applied Mechanics and Engineering 329 (2018)
    The process of single-lip deep hole drilling is used in various industrial applications for the production of small bores with a high length to diameter ratio. Especially the cooling and the lubrication of the machining zone have a great influence on the tool life, on the transport of chips, as well as on the quality of the resulting bore. In this paper, two approaches for the modeling and simulation of drilling processes are presented. On the one hand, the Finite Volume Method is used for the stationary simulation of the flow field. Assuming the entire bore to be filled with coolant, the focus is laid on a precise description of important fluid mechanical quantities along the cutting edges. The results show that the mass exchange of the cooling lubricant close to the cutting edge is far too low in order to guarantee the required cooling effect. On the other hand, a coupled meshless approach for the transient simulation is presented. The cooling lubricant is there modeled by the Smoothed Particle Hydrodynamics method and the Discrete Element Method is used for the description of chips. In contrast to the Finite Volume simulation, the main focus is laid on the evolution of the free surfaces and the transport of particles. The results show that the transport of chips by the cooling lubricant can be described well. Furthermore, also the transient Smoothed Particle Hydrodynamics simulations show an insufficient mass exchange behind the cutting edges matching the steady-state results from the Finite Volume simulation with a bore completely filled with coolant. © 2017 Elsevier B.V.
    view abstract10.1016/j.cma.2017.09.015
  • Point-based tool representations for modeling complex tool shapes and runout for the simulation of process forces and chatter vibrations
    Wiederkehr, P. and Siebrecht, T. and Baumann, J. and Biermann, D.
    Advances in Manufacturing 6 (2018)
    Geometric physically-based simulation systems can be used for analyzing and optimizing complex milling processes, for example in the automotive or aerospace industry, where the surface quality and process efficiency are limited due to chatter vibrations. Process simulations using tool models based on the constructive solid geometry (CSG) technique allow the analysis of process forces, tool deflections, and surface location errors resulting from five-axis machining operations. However, modeling complex tool shapes and effects like runout is difficult using CSG models due to the increasing complexity of the shape descriptions. Therefore, a point-based method for modeling the rotating tool considering its deflections is presented in this paper. With this method, tools with complex shapes and runout can be simulated in an efficient and flexible way. The new modeling approach is applied to exemplary milling processes and the simulation results are validated based on machining experiments. © 2018, Shanghai University and Springer-Verlag GmbH Germany, part of Springer Nature.
    view abstract10.1007/s40436-018-0219-8
  • Simulation based analysis and optimisation of the cutting edge micro shape for machining of nickel-base alloys
    Biermann, D. and Amuth, R. and Hess, S. and Tiffe, M.
    Procedia CIRP 67 (2018)
    The modification of the cutting edge micro shape by wet abrasive jet machining is utilized to increase the performance of cutting tools by means of productivity and tool life. However, for numerous cutting processes the optimal micro shape of cutting edges is still unknown. In this regard, the paper deals with a method to predict optimized cutting edge micro shapes using FE-Simulation. The method includes the consideration of the local process conditions like radius dependent cutting speeds in drilling processes depicted by the example of drilling a nickel-base alloy. In this paper first simulation analyses are compared to experimental investigations. In addition, predictions of the mechanical loads dependent on the applied cutting edge micro shapes are presented. © 2017 The Authors.
    view abstract10.1016/j.procir.2017.12.214
  • Simulation of surface structuring considering the acceleration behaviour by means of spindle control
    Freiburg, D. and Finkeldey, F. and Hensel, M. and Wiederkehr, P. and Biermann, D.
    International Journal of Mechatronics and Manufacturing Systems 11 (2018)
    Due to the increasing demands on surface quality of machined surfaces, deviations of the feed velocity, which can occur in complex 5-axis milling processes and are caused by the insufficient acceleration and deceleration behaviour of the machining centre, have to be avoided. This is crucial in the case of surface structuring by means of high-feed milling. The high-feed rate can be used to generate quasi-deterministic surface structures on forming tools. Applying surface structures for forming processes, the friction can be tailored to improve the form filling of small cavities. However, in order to generate homogeneous surface structures, it is important to ensure a constant feed per tooth during the milling process. In this work, a novel approach for the predicting surface structures using a geometric physically-based simulation system is shown. Furthermore, an empirical model was developed which represents the acceleration and deceleration behaviour of the used machining centre for predicting the deviations of the feed rate. Therefore, it is possible to take the alternating feed rate into account when simulating the milling process. In addition, a control approach, for adapting the spindle speed online, is used to keep the tooth feed constant. © 2018 Inderscience Enterprises Ltd.
    view abstract10.1504/IJMMS.2018.091178
  • Transient simulation of cooling-lubricant flow for deep-hole drilling-processes
    Schnabel, D. and Özkaya, E. and Biermann, D. and Eberhard, P.
    Procedia CIRP 77 (2018)
    Today, the process of single-lip deep-hole drilling becomes more and more important for many industrial applications, e.g. in aerospace engineering, automotive industry or for medical products. The cooling lubricant is not only most important for the quality of the resulting bore, but also for the evacuation of chips and for increasing the tool life. For that reason, a coupled particle approach for the simulation of cooling lubricant in the context of deep-hole drilling was developed. The cooling lubricant in the presented simulations is described by the Smoothed Particle Hydrodynamics method and the drill chips are described by Discrete Element multispheres. From the performed simulations, one can see that the coupled particle methods together with meshbased Computational Fluid Dynamics simulations are suitable for the description of the flow field and the chip evacuation. Furthermore, the simulations of the cooling lubricant for a single-lip drill show a velocity sink behind the cutting edge at the tip of the drilling tool. This result indicates great potential for the optimization of the tool geometry, presumably leading to an increased tool life as well as an improved cooling behaviour. Considering inlet pressures above 20 bar, and a drill diameter of 2 mm, the presented systems are challenging, with particle velocities above 100 m/s. However, the results of the performed simulations show a great potential for the application of coupled particle methods and meshbased Computational Fluid Dynamics for the investigation of the coolant flow. It can be seen that the Smoothed Particle Hydrodynamics method is an interesting alternative compared to meshbased methods, due to its property to describe the transient evolution of the cooling lubricant without any special treatment of free surfaces and interfaces that experience great topological changes. Especially for simulations which do not assume the evacuation channel to be entirely filled with cooling lubricant, the meshless nature of particle methods is beneficial. © 2018 The Authors. Published by Elsevier Ltd.
    view abstract10.1016/j.procir.2018.08.224
  • Adjustment of friction by duplex-treated, bionic structures for Sheet-Bulk Metal Forming
    Tillmann, W. and Stangier, D. and Lopes-Dias, N.-F. and Biermann, D. and Krebs, E.
    Tribology International 111 (2017)
    Bionic structures were applied on hardened AISI M3:2 and duplex-treated by means of plasmanitriding. Subsequently, a thin hard CrAlN coating was deposited on the substrate. The tribological properties of the structure systems were investigated in the full contact area, using identical friction partners (steel DP 600) of the forming process. The tribological behavior was analyzed in fundamental laboratory tests, using a modified tribometer and subsequently evaluated in application-orientated adapted ring-compression tests. Bionic structures are suitable to locally adjust the friction condition and proved to be an appropriate method to control the material flow of sheet metals in bulk forming operations. However, process related micro burrs lead to a roughness increase during subsequent treatments, thus increasing the friction and adhesive effects. © 2017 Elsevier Ltd
    view abstract10.1016/j.triboint.2017.02.037
  • CFD simulation for internal coolant channel design of tapping tools to reduce tool wear
    Biermann, D. and Oezkaya, E.
    CIRP Annals - Manufacturing Technology 66 (2017)
    This paper presents the analysis and controlled modification of the coolant flow in tapping processes by means of Computational Fluid Dynamics (CFD). First, a conventional straight flute tapping tool was analyzed and the results of the CFD simulation show, that the cutting edges are not sufficiently supplied with coolant. Therefore, the design of the internal coolant channels was modified based on these simulation results. To validate the CFD simulation, experimental tests were performed, using an optimized tool. The applied modifications lead to a reduction of the tool wear and an increase of the tool's performance of about 36% was achieved. © 2017
    view abstract10.1016/j.cirp.2017.04.024
  • Core Drilling of Fiber Reinforced Materials using Abrasive Tools
    Biermann, D. and Bathe, T. and Rautert, C.
    Procedia CIRP 66 (2017)
    Due to the inhomogeneous structure and the high abrasiveness of fiber-reinforced materials, conventional tools rapidly suffer from a cutting edge rounding which leads to ploughing and consequently to delamination. To reduce these wear-induced damages diamond-mounted points have been utilized to perform series of drilling tests. Based on the suitability of these tools and for enhancing the chip removal and cooling, the shape of the base body and grooves and the coolant supply were varied initially. For the transferability of the developed techniques different fiberreinforced materials as well as a variation of the machining kinematics were employed. © 2017 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2017.03.304
  • Experimental investigations for a simulative optimization of the cutting edge design of twist drills used in the machining of Inconel 718
    Biermann, D. and Bücker, M. and Tiffe, M. and Özkaya, E.
    Procedia Manufacturing 14 (2017)
    Many of the properties that determine Inconel 718 for the use in high-temperature applications also make it hard to machine at the same time. In order to improve the drilling tools' life span by a modification of the flank face, finite element simulations have to be carried out that require precise input data from real machining experiments. In this work, investigations that examine the occurring mechanical loads alongside the tool's cutting edge were combined with analyses of the tool's contact zones. It could be shown how the distribution of mechanical loads differs along the cutting edge and how the occurring forces increase as larger parts of the cutting edge come into engagement. The experiments' results lead to the conclusion that the length of the tool-workpiece contact zone is linked to the applied feed rate and that material smearing occurs almost exclusively on the tool's rake face. The gathered results will later allow simulations to develop an optimized tool design implementing a new cutting edge geometry. © 2017 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.promfg.2017.11.002
  • Experimental studies and FEM simulation of helical-shaped deep hole twist drills
    Oezkaya, E. and Michel, S. and Biermann, D.
    Production Engineering (2017)
    This study investigates the chip formation in drilling of AISl 316L stainless steel using TiAIN coated helical-shaped deep hole twist drills. The aim of this research is to determine suitable cutting parameters with a focus on favourable chip formation, to achieve a better process stability. The experimental investigations were conducted with varying cutting speed, feed rate and cooling lubricant pressure, in stages that were based on the recommendations of the tool manufacturer. In addition to the experimental tests, the mechanical loads and chip formation were simulated with the aim of providing a basis for the simulative development of the tool shape and the cutting parameters. With mathematical methods, a geometrical kinematic imprint, in accordance to the axial feed force of the helical-shaped deep hole twist drill, was implemented into the three-dimensional workpiece model. Based on the experimental results, which show that the chip shape has a great dependence on the feed rate, which in turn strongly affects the feed force and the drilling torque suitable cutting parameters were chosen for the simulation. The simulation results were validated with the experimental data and show a good agreement. © 2017 German Academic Society for Production Engineering (WGP)
    view abstract10.1007/s11740-017-0779-7
  • Front Face Flow Drilling of Lightweight Cast Materials
    Biermann, D. and Walther, F. and Hannich, S. and Wittke, P.
    Procedia Engineering 207 (2017)
    Front face flow drilling, which has been investigated at the Institute of Machining Technology (ISF), TU Dortmund University, represents a new application of the conventional flow drilling process. With this new technique it is possible to form closed holes with diameters, which can exceed the local wall thickness of the profile. By using a subsequent threading operation, it is possible to generate solid joints. In this article investigations regarding the machining of the aluminium cast alloy AlSi10Mg are presented. The feasibility of the front face flow drilling application was analysed for the machining of thin profiles with a wall thickness of tW = 6 mm. Flow drilling tools with a diameter of dFD = 5.4 mm have been used. Feed forces as well as torques were measured during the flow drilling process. In order to generate solid threads, a high quality of the formed holes has to be ensured. To quantify the quality, measurements of the circularity as well as the diameters were carried out. Both aspects can have an influencing effect on the threading operation. Due to the low formability of the used alloys, adjustments of the flow drilling process had to be realised. Besides the variation of process parameters such as peripheral speed and feed velocity, a pre-heating of the tool was conducted to raise the formability of the workpiece material and to increase the process stability. The pre-heating of the tool was accomplished by using a portable induction system with an integrated temperature control. As a result of the investigations, suitable process strategies will be recommended regarding a stable front face flow drilling operation of the lightweight cast alloy AlSi10Mg. Further research regarding front face flow drilling is planned towards an adaptation to magnesium cast alloys. © 2017 The Authors. Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2017.10.858
  • High-quality cutting edge preparation of micromilling tools using wet abrasive jet machining process
    Krebs, E. and Wolf, M. and Biermann, D. and Tillmann, W. and Stangier, D.
    Production Engineering (2017)
    The cutting edge preparation is a common process in the production chain of cemented carbide macro tools. It is used to reduce failures resulting from grinding and to generate a specific cutting edge geometry that is appropriate for the application of the cutting tool. The adhesion of a subsequently applied coating is also increased due to the rounded and more regular shape of a prepared cutting edge. Even though cutting edge preparation is able to significantly increase the life of macro tools, it is not state of the art in the production of micro tools since common preparation processes have not been developed and established for this case of application. Within the investigations, the feasibility of the wet abrasive jet machining process for the preparation of micromilling tools is analysed. For this purpose, the preparation process is refined which allows an effective reduction of the defects and a successful adjustment of different rounding sizes of the cutting edge in a relatively short preparation time. In addition, a high-quality statistical model is achieved to describe the interdependency of the process parameters. In conclusion, TiAlN layers are applied on the rounded cutting edges by a PVD-process without obstructive droplets. © 2017 German Academic Society for Production Engineering (WGP)
    view abstract10.1007/s11740-017-0787-7
  • Improvement strategies for the formfilling in incremental gear forming processes
    Sieczkarek, P. and Wernicke, S. and Gies, S. and Tekkaya, A.E. and Krebs, E. and Wiederkehr, P. and Biermann, D. and Tillmann, W. and Stangier, D.
    Production Engineering 11 (2017)
    Incremental Sheet-Bulk Metal Forming offers an innovative and flexible approach for the manufacturing of gears. An insufficient formfilling of the generated gearing, especially of the first tooth formed, is observed. Aiming for a formfilling improvement of the first tooth element, three influencing factors were investigated. First, the prevailing friction is analyzed and a possibility for its adjustment is offered by a tailored adaption of the tool surface topographies. These were manufactured by micromilling, EDM and polishing processes and partially covered by CrAlN PVD-coatings. Based on ring-compression tests, which were performed to determine the resulting friction conditions, the analyzed topographies were transferred onto real tool surfaces and used in the incremental gear forming process. Second, the influence on the formfilling of the blank cutting process and the resulting sheet edge properties were investigated. The third aspect to enhance the formfilling of the gear elements was the modification of the process strategy of the incremental forming process. Due to different conditions for the initial and the following indentations, a preforming operation was investigated in order to realize a similar material flow for all indentations. With the combination of the best parameters regarding the tool surface, the blank cutting process and the forming strategy, an improvement of the formfilling of the first formed gear element by up to 33% and for the following gears by up to 13% was achieved. © 2017 German Academic Society for Production Engineering (WGP)
    view abstract10.1007/s11740-017-0764-1
  • In situ chip formation analyses in micro single-lip and twist deep hole drilling
    Kirschner, M. and Michel, S. and Berger, S. and Biermann, D. and Debus, J. and Braukmann, D. and Bayer, M.
    International Journal of Advanced Manufacturing Technology (2017)
    Growing competitive pressure forces companies to optimise process productivity and shorten primary production times. At the same time, the resulting manufacturing quality must be kept on a high level. In the automotive sector, deep hole drilling with smallest tool diameters is an important process, e.g. to produce lubrication holes in crankshafts and fuel channels in injectors. A crucial criterion for the achievable productivity and manufacturing quality with respect to the dimensional and shape tolerances as well as the surface quality in smallest diameter deep hole drilling is the chip formation. Therefore, in-depth analyses regarding the mechanisms of chip formation at the cutting edge and the chip removal along the chip flutes are indispensable. To accomplish an in-depth chip formation analysis in smallest diameter deep hole drilling, a new methodology of analysis has been developed. Samples made of the particular test material are inserted into acrylic glass carriers, and the chip formation in the operating zone and the chip removal are documented by high-speed microscopy. In this paper, the experimental setup of the newly developed methodology of analysis and the experimental results for single-lip and twist deep hole drilling of high-strength bainitic steel with smallest diameters are shown. The investigations show the dependence of chip formation on the changes of the microstructure of the cutting edge due to tool wear, and form the basis for an optimization of the tools. In addition to that, a new approach to visualise machining processes running under non-transparent coolant is presented. © 2017 Springer-Verlag London Ltd., part of Springer Nature
    view abstract10.1007/s00170-017-1339-1
  • Investigations on chip flow control for coil edge machining: Untersuchungen zur Kontrolle der Spanabfuhr bei der Bandkantenbearbeitung
    Tiffe, M. and Vogel, F. and Biermann, D. and Geltz, N.
    Materialwissenschaft und Werkstofftechnik 48 (2017)
    Steel strips are frequently used in the metal working industry for the manufacturing of tubes and bearing sleeves. These steel strips are produced by cold and warm rolling and are commonly coiled up for transportation purposes. Moreover, the obtained coils are split into customized sizes. In order to use the steel strips for further processing the edges need to be machined with respect to deburring and joint preparation. Therefore, specialized machine tools are used which apply common turning inserts with a translational cutting motion. On the one hand this process is high efficient but on the other hand the process reliability is affected by the formation of long continuous chips. In order to meet the requirements for an increased process reliability investigations on chip flow control are carried out with the aid of the finite element method (FEM). The acquired results are presented in this article. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
    view abstract10.1002/mawe.201600733
  • Mechanistic modeling of micro-drilling cutting forces
    Anand, R.S. and Patra, K. and Steiner, M. and Biermann, D.
    International Journal of Advanced Manufacturing Technology 88 (2017)
    This paper presents a mechanistic model for micro-drilling cutting forces that includes the cutting edge radius and the minimum chip thickness size effects. The proposed model considers three different cutting regions, i.e., ploughing-dominant, transition, and shearing-dominant, based on these size effects. Specific normal force and specific friction force coefficients have been determined through model calibration using micro-drilling experimental results. Model is validated with micro-drilling experimental results of different cutting conditions and of different machining environments. Comparisons of model simulated and experimental results show that ploughing force contributions are significant, especially at low feed rates. The proposed model has also been applied to characterize size effects in micro-drilling. © 2016, Springer-Verlag London.
    view abstract10.1007/s00170-016-8632-2
  • Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools
    Tillmann, W. and Schaak, C. and Biermann, D. and Aßmuth, R. and Goeke, S.
    IOP Conference Series: Materials Science and Engineering 181 (2017)
    Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means of wet abrasive jet machining. © Published under licence by IOP Publishing Ltd.
    view abstract10.1088/1757-899X/181/1/012011
  • Segmented and mathematical model for 3D FEM tapping simulation to predict the relative torque before tool production
    Oezkaya, E. and Biermann, D.
    International Journal of Mechanical Sciences 128-129 (2017)
    The conventional tapping tool development consists of costly investigative experiments. The development time and cost can be significantly reduced, if these test were replaced by virtual analyses, before the tool prototypes are fabricated. Compared to turning, milling and drilling, in which many valid simulative methods have been established, the tapping process has been given rather little research attention. In this paper an approach is presented, which could be used during the design phases, to predict the relative torque, so that resources, energy and cost can be saved. Based on a simulated reference model, which is in good agreement with corresponding experimental results, the problem of a long computing time could be solved by using a proper segmentation method, which offers a process simulation along the whole chamfer length. With an according mathematical model, the discontinuous torque curve could be summarized to a total load cycle. © 2017 Elsevier Ltd
    view abstract10.1016/j.ijmecsci.2017.04.011
  • A Framework for Multi-level Modeling and Optimization of Modular Hierarchical Systems
    Wagner, T. and Biermann, D.
    Procedia CIRP 41 (2016)
    Most products and manufacturing systems (MS) have an inherent hierarchical structure. They are composed of multiple subsystems, such as machines, process components, or resources. In order to optimize the control parameters of such systems, manufacturing planners often follow a global black-box approach. The optimization, thus, neglects the hierarchical structure encoded in the model. All subsystems and their components have to meet individual constraints and show specific uncertainty in their output. By extracting the information, which modules violate the constraints, the optimization algorithm could focus on the parameters of this specific module. Moreover, the planner can define objectives evaluating the robustness or sensitivity of a specific solution based on the knowledge of the hierarchical dependencies and about the uncertainty in the outputs. To accomplish this, the structure of the optimized system must be known to the respective methods applied. In this paper, the dependencies of the subsystems are defined by means of a tree structure. Based on this structure, different possibilities to define and solve the corresponding optimization problem are introduced. In addition, a concept for addressing the robustness of an MS with regard to the uncertainty of the components within the optimization model is proposed. As a practical example, a hot compaction process for manufacturing thermoplastic composites is formalized using the tree structure. Individual nonlinear empirical models simulate the input-output behavior of each subsystem. Based on this formalization, the results of single- and multi-objective optimization methods are compared and their strengths and weaknesses are discussed. © 2016 The Authors.
    view abstract10.1016/j.procir.2015.12.050
  • A non-rigid registration method for the efficient analysis of shape deviations in production engineering applications
    Schweinoch, M. and Schäfer, R. and Sacharow, A. and Biermann, D. and Buchheim, C.
    Production Engineering 10 (2016)
    A common requirement in production engineering applications is the comparison of designed and as-built parts. Due to manufacturing influences and geometric changes incorporated during physical prototyping, there may exist significant deviations between these shapes. In order to compensate the manufacturing influences and to incorporate geometric changes into the virtual design, a detailed analysis of the deviations is required. The designed (or reference) shape is usually given in terms of a CAD data set, while the as-built (or test) geometry is acquired by digitization of the physically manufactured prototype. Given these two geometries, one is faced with the problem of determining points of correspondence between them. This is also referred to as registration. In rigid registration, correspondences are determined by first aligning the two geometries rigidly using a best-fit approach. Subsequently, the correspondences between the aligned geometries are determined by finding for a point of one shape the closest surface point on the other. While several efficient rigid registration methods exist, they do not account for shape deviations, resulting in inaccurate correspondences when applied to such geometries. Non-rigid registration methods, conversely, do not search for a global best-fit alignment, but instead affect a deformation of the one geometry onto the other, allowing for an improved correspondence calculation. Most published state-of-the-art non-rigid registration methods are not necessarily applicable to production engineering scenarios due to, among others, the typical data sizes and the required level of accuracy in the correspondence determination. A further hindrance is their lack of shop-floor applicability, attributable to their calculation times as well as to the expertise that their application requires on behalf of the user. This paper presents a non-rigid registration method for the efficient calculation of correspondences in production engineering scenarios. By combination of several established methods from the field of geometric modeling, the test shape is iteratively deformed onto the reference shape. When the deformed test shape satisfiably approximates the reference geometry, correspondences are determined by projection. The procedure is applied to the problem of springback behavior, which arises in sheet metal forming. A validation of the method is achieved by comparing the calculated correspondences with the ideal correspondences, as determined by finite element simulation. © 2016, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-016-0660-0
  • Advanced Simulation-based Design of High Performance Machining Processes
    Biermann, D. and Bleckmann, T. and Schumann, S. and Iovkov, I.
    Procedia CIRP 46 (2016)
    The development of high performance machining processes is a key aspect to achieve higher productivity, efficiency and performance in modern production systems. In order to reduce the corresponding effort and costs, simulation systems are one possibility to support the design and the optimization of manufacturing processes. In this article, three different application examples with respect to milling, grinding and deep-hole drilling operations are presented. In this context, both finite-element and geometric-kinematic simulation approaches are applied to model the different challenging issues of the corresponding machining process. © 2016 The Authors.
    view abstract10.1016/j.procir.2016.03.167
  • Cryogenic manufacturing processes
    Jawahir, I.S. and Attia, H. and Biermann, D. and Duflou, J. and Klocke, F. and Meyer, D. and Newman, S.T. and Pusavec, F. and Putz, M. and Rech, J. and Schulze, V. and Umbrello, D.
    CIRP Annals - Manufacturing Technology 65 (2016)
    Cryogenically assisted manufacturing processes are emerging as environmentally-benign, toxic-free, hazardless operations, producing functionally superior products. This paper presents an overview of major cryogenic manufacturing processes, summarizing the state-of-the-art and significant developments during the last few decades. It begins with a summary of historic perspectives, including definitions, scope, and proceeds to analysis of process mechanics and material performance covering tribological and thermo-mechanical interactions, followed by surface integrity, product quality and performance in cryogenic manufacturing. Process analysis and applications includes machining, forming and grinding. Economic, safety and health issues are then discussed. Finally, progress in developing predictive performance models and future outlook are presented. © 2016 CIRP
    view abstract10.1016/j.cirp.2016.06.007
  • Determination of force parameters for milling simulations by combining optimization and simulation techniques
    Freiburg, D. and Hense, R. and Kersting, P. and Biermann, D.
    Journal of Manufacturing Science and Engineering, Transactions of the ASME 138 (2016)
    Milling is a machining process in which material removal occurs due to the rotary motion of a cutting tool relative to a typically stationary workpiece. In modern machining centers, up to and exceeding six degrees of freedom for motion relative to the tool and workpiece are possible, which results in a very complex chip and force formation. For the process layout, simulations can be used to calculate the occurring process forces, which are needed, e.g., for the prediction of surface errors of the workpiece, or for tool wear and process optimization examinations. One limiting factor for the quality of simulation results is the parametrization of the models. The most important parameters for milling simulations are the ones that calibrate the force model, as nearly every modeled process characteristic depends on the forces. This article presents the combination of a milling simulation with the Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimization algorithm for the fast determination of force parameters that are valid for a wide range of process parameters. Experiments were conducted to measure the process forces during milling with different process parameters. The measured forces serve as basis for tests regarding the quality of the determined force parameters. The effect of the tool runout on the optimization result is also discussed, as this may have significant influence on the forces when using tools with more than one tooth. The article ends with a conclusion, in which some notes about the practical application of the algorithm are given. © 2016 by ASME.
    view abstract10.1115/1.4031336
  • Experimental and numerical analysis of tribological effective surfaces for forming tools in Sheet-Bulk Metal Forming
    Kersting, P. and Gröbel, D. and Merklein, M. and Sieczkarek, P. and Wernicke, S. and Tekkaya, A.E. and Krebs, E. and Freiburg, D. and Biermann, D. and Weikert, T. and Tremmel, S. and Stangier, D. and Tillmann, W. and Matthias, S. and Reithmeier, E. and Löffler, M. and Beyer, F. and Willner, K.
    Production Engineering 10 (2016)
    Sheet-Bulk Metal Forming (SBMF) allows the manufacture of complex parts with integrated functional form elements, such as teeth and thickened areas. Therefore, bulk forming operations are applied to sheets with initial thicknesses of 2 or 3 mm. The design and functionality of the tools are as important as the process itself. Therefore, the working group "Tools" of the Transregional Collaborative Research Centre on Sheet-Bulk Metal Forming (CRC/TR73) focuses on the optimization of the technical tool design. By varying topographies or applying tailored coatings, the friction behavior is changed to achieve a better form filling and to reduce process forces during the forming operations. In this paper, the potential of different tailored surfaces is validated by simulations and experimental studies. The tribological behavior of 14 surface microstructures is evaluated using a half-space model in order to select structures suitable for application. Those were characterized experimentally by ring-compression and pin-extrusion tests. The determined friction factors were used in a forming simulation to predict the form filling of small cavities in a flow forming operation. Furthermore, special attention is paid to the utilization of the anisotropic behavior of specific structures. The results were validated by an incremental gear forming process. © 2016, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0651-6
  • Experimental studies and CFD simulation of the internal cooling conditions when drilling Inconel 718
    Oezkaya, E. and Beer, N. and Biermann, D.
    International Journal of Machine Tools and Manufacture 108 (2016)
    When drilling the superalloy Inconel 718 twist drills are faced with high thermomechanical loads. Owing to the low thermal conductivity of the workpiece material a large amount of the generated heat has to be transported away from the tool by the coolant. In this paper, the influence of the coolant pressure and the diameter of the coolant channels have been studied. The experiments have been supported by using computational fluid dynamics (CFD) simulations and were focused on the tool wear and the bore quality. The CFD simulation is a valuable tool which supported the present investigation, that a higher mass flux has no advantage regarding tool life and bore quality; moreover, the modification of the channel diameters has not reduced the thermal loads. In all investigated processes, dead zones near the cutting edge and the counter edge could not be reduced by increasing the flow rate. Only by the use of higher coolant pressures, the tool life could be significantly increased, as well as the bore quality. The investigations prove that especially when metrological methods reach their limits, the CFD is a suitable tool; which supports the design process effectively by giving a better insight into the coolant flow resulting from the complex drilling processes. © 2016 Elsevier Ltd.
    view abstract10.1016/j.ijmachtools.2016.06.003
  • Indication of worn WC/C surface locations of a dry-running twin-screw rotor by the oxygen incorporation in tungsten-related Raman modes
    Debus, J. and Schindler, J.J. and Waldkirch, P. and Goeke, S. and Brümmer, A. and Biermann, D. and Bayer, M.
    Applied Physics Letters 109 (2016)
    By comparing the worn and untouched locations of a tungsten-carbide/carbon surface of a dry-running twin-screw rotor, we demonstrate that tungsten-oxide Raman modes become observable only at worn locations and the integral intensity of the Raman line at 680 cm-1, which is related to the incipient oxidation of the tungsten-carbide stretching mode, is enhanced. Its frequency and width moreover change significantly, thus indicating the mechanical distortion of the bonding that has been occurred during the wearing process. The shape of the tungsten-oxide Raman lines, resembling the Voigt function, hints at a surface morphology that is a characteristic for an amorphous solid environment. Our Raman scattering results may be exploited to characterize the degree of wear of coated surfaces and to identify signatures of a tribological layer. © 2016 Author(s).
    view abstract10.1063/1.4966145
  • Influence of Machine Hammer Peening on the Tribological Behavior and the Residual Stresses of Wear Resistant Thermally Sprayed Coatings
    Rausch, S. and Wiederkehr, P. and Biermann, D. and Zabel, A. and Selvadurai, U. and Hagen, L. and Tillmann, W.
    Procedia CIRP 45 (2016)
    WC-W2C iron based cermet coatings are widely used in the field of wear protection. In surface engineering, machine hammer peening (MHP) is a novel surface treatment technology, which enhances the surface properties, especially for surfaces in tribological contact. In this study, the wear behavior of peened WC-W2C FeCrCMnSi arc sprayed coatings is characterized and compared to conventional coatings under as-sprayed conditions. The resulting strain hardening effects were measured by mechanical response using nanoindentation. In addition, residual stresses at the surfaces were determined using X-ray diffraction and the sin2ψ method. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
    view abstract10.1016/j.procir.2016.02.059
  • Investigation of the tribological properties of high-feed milled structures and Cr-based hard PVD-coatings
    Tillmann, W. and Stangier, D. and Laemmerhirt, I.-A. and Biermann, D. and Freiburg, D.
    Vacuum 131 (2016)
    Sheet-bulk metal forming is an innovative approach to manufacture complex components which, due to secondary design features, have integrated as well as extended functions. A complex tribological load collective, that has not yet been sufficiently investigated, results from the high degree of deformation, high contact normal stresses of up to 3 GPa with a simultaneously high relative movement of the material, as well as the preference for local adaption of the material flow. Surface structures are a promising approach to locally adapt and control the material flow. Within this context, the present contribution investigates the influence as well as the interdependencies of three high-feed milled deterministic surface structures, combined with Cr-based PVD-hard coatings (CrAlN and CrAlCN), on the friction and wear behavior. The results show that CrAlN as well as CrAlCN-coatings significantly enhance the tribological property profile of the structured surfaces in comparison to hardened ASP2023. Despite the possibility to produce near net-shaped coatings, the wear resistance of the structures is increased by Cr-based hard materials, whereas the uncoated structures are destroyed. All three chosen surface structures show adherent material transfer of the 100Cr6 balls during the sliding contact. Especially the abrasive wear caused by the coated asperities of the structures leads to plowing of the 100Cr6 counter body resulting in debris on the CrAlN and CrAlCN surface. © 2016 Elsevier Ltd. All rights reserved.
    view abstract10.1016/j.vacuum.2016.05.024
  • Model based optimization of a statistical simulation model for single diamond grinding
    Herbrandt, S. and Ligges, U. and Ferreira, M.P. and Kansteiner, M. and Biermann, D. and Tillmann, W. and Weihs, C.
    Computational Statistics (2016)
    We present a model for simulating normal forces arising during a grinding process in cement for single diamond grinding. Assuming the diamond to have the shape of a pyramid, a very fast calculation of force and removed volume can be achieved. The basic approach is the simulation of the scratch track. Its triangle profile is determined by the shape of the diamond. The approximation of the scratch track is realized by stringing together polyhedra. Their sizes depend on both the actual cutting depth and an error implicitly describing the material brittleness. Each scratch track part can be subdivided into three three-dimensional simplices for a straightforward calculation of the removed volume. Since the scratched mineral subsoil is generally inhomogeneous, the forces at different positions of the workpiece are expected to vary. This heterogeneous nature is considered by sampling from a Gaussian random field. To achieve a realistic outcome the model parameters are adjusted applying model based optimization methods. A noisy Kriging model is chosen as surrogate to approximate the deviation between modelled and observed forces. This deviation is minimized and the results of the modelled forces and the actual forces from conducted experiments are rather similar. © 2016 Springer-Verlag Berlin Heidelberg
    view abstract10.1007/s00180-016-0669-z
  • Modelling and simulation of thermal effects in internal traverse grinding of hardened bearing steel
    Biermann, D. and Holtermann, R. and Menzel, A. and Schumann, S.
    CIRP Annals - Manufacturing Technology 65 (2016)
    Internal traverse grinding with electro-plated cBN wheels combines the advantages of both internal hard turning and internal grinding, enabling a high material removal rate along with a high surface quality. The drawback, however, is a high thermal load on the workpiece, resulting in shape and dimension errors of the finished part. This paper deals with the compensation of these manufacturing errors with a hybrid simulation system. It combines thermo-mechanically coupled finite element models on both meso- and macro-scale with a scale-bridging kinematic simulation system, enabling the prediction of the resulting temperatures and the development of corresponding simulation-based compensation strategies. © 2016 CIRP
    view abstract10.1016/j.cirp.2016.04.005
  • Numerical Determination of Process Values Influencing the Surface Integrity in Grinding
    Holtermann, R. and Schumann, S. and Zabel, A. and Biermann, D. and Menzel, A.
    Procedia CIRP 45 (2016)
    Internal traverse grinding with electroplated cBN wheels using high-speed process conditions combines high material removal rates and a high surface quality of the workpiece in one single grinding stroke. In order to capture the macroscopic and mesoscopic thermo-mechanical loads onto the workpiece during internal traverse grinding, numerical simulations are conducted at the two scales. This results in a hybrid approach coupling two finite element models with a geometric kinematic simulation. The article focuses on the influence of multiple grain engagements onto a surface layer region using a two-dimensional chip formation simulation. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
    view abstract10.1016/j.procir.2016.02.072
  • Optimization of a simulation for inhomogeneous mineral subsoil machining
    Herbrandt, S. and Weihs, C. and Ligges, U. and Ferreira, M. and Rautert, C. and Biermann, D. and Tillmann, W.
    Studies in Classification, Data Analysis, and Knowledge Organization (2016)
    For the new generation of concrete which enables more stable constructions, we require more efficient tools. Since the preferred tool for machining concrete is a diamond impregnated drill with substantial initial investment costs, the reduction of tool wear is of special interest. The stochastic character of the diamond size, orientation, and position in sintered segments, as well as differences in the machined material, justifies the development of a statistically motivated simulation. In the simulations presented in the past, workpiece and tool are subdivided by Delaunay tessellations into predefined fragments. The heterogeneous nature of the ingredients of concrete is solved by Gaussian random fields. Before proceeding with the simulation of the whole drill core bit, we have to adjust the simulation parameters for the two main components of the drill, diamond and metal matrix, by minimizing the discrepancy between simulation results and the conducted experiments. Due to the fact that our simulation is an expensive black box function with stochastic outcome, we use the advantages of model based optimization methods. © Springer International Publishing Switzerland 2016.
    view abstract10.1007/978-3-319-25226-1_41
  • Process chains for high-precision components with micro-scale features
    Uhlmann, E. and Mullany, B. and Biermann, D. and Rajurkar, K.P. and Hausotte, T. and Brinksmeier, E.
    CIRP Annals - Manufacturing Technology 65 (2016)
    This keynote paper addresses the manufacturing of high-precision components with micro-scale features, and the associated process chain considerations. Three workpiece classifications as well as a micro-production process chain (MPPC) model are defined. A review of capabilities and advances in micro-manufacturing technologies, metrology, and equipment demonstrates increased versatility across varied applications, while also highlighting limitations. Challenges in the development of process chains are presented using results of the MPPC program of the Collaborative Working Group on Micro-Production Engineering. Finally, a guide for machining high-precision components with micro-scale features in process chains is given with respect to machine tools, tools, technology and environmental conditions. © 2016 CIRP
    view abstract10.1016/j.cirp.2016.05.001
  • Tribological measures for controlling material flow in sheet-bulk metal forming
    Löffler, M. and Andreas, K. and Engel, U. and Schulte, R. and Groebel, D. and Krebs, E. and Freiburg, D. and Biermann, D. and Stangier, D. and Tillmann, W. and Weikert, T. and Wartzack, S. and Tremmel, S. and Lucas, H. and Denkena, B. and Merklein, M.
    Production Engineering 10 (2016)
    Sheet-bulk metal forming (SBMF) is characterized by successive and/or simultaneous occurrence of quite different load conditions regarding stress and strain states. These conditions significantly influence the material flow and thus the geometrical accuracy of the components. To improve the product quality a control of the material flow is required. An appropriate approach is given by locally adapted tribological conditions due to surface modifications of tool and workpiece, so-called tailored surfaces. Within the present study different methods to adapt the surfaces are presented and investigated with respect to their tribological effectiveness in SBMF. In a first step, requirements regarding necessary adaptions of the friction values for two SBMF processes are numerically defined. Based on the requirements different tailored surfaces are presented and analyzed regarding their tribological influence. Finally, the potential of surface modifications to improve SBMF processes is shown. © 2016, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-016-0695-2
  • Wear behavior of tribologically optimized tool surfaces for incremental forming processes
    Sieczkarek, P. and Wernicke, S. and Gies, S. and Tekkaya, A.E. and Krebs, E. and Wiederkehr, P. and Biermann, D. and Tillmann, W. and Stangier, D.
    Tribology International 104 (2016)
    The mechanical wear behavior of forming tools is the limiting factor during an incremental gear-forming process. These forming tools with a simply shaped geometry are exposed to high forming forces. Additionally, the necessary workpiece chambering, which is characteristic for this incremental process restricts the dimensioning of the tools. Thereby, the geometrical design of the forming tools is limited, which leads to a decreased lifetime. Functional structures on the tool surfaces can influence the occurring loading and wear behavior by reducing the contact area, the supply of lubricant pockets, and by a controlled influence and adjustment of the occurring material flow. For the extension of the tool's lifetime, different surface concepts and combinations with CrAlN PVD-coatings are investigated. To offer conditions with a high tool load, the investigations are focused on an incremental gear forming process with a simple one-wedge forming tool. The results show abrasive and adhesive wear characteristics, as well as outbreaks, and crack formations. The crack propagation on the flank leads to a chipping of the tool tip, hence limiting the tool life. Compared to the reference tool, a surface structure combined with a PVD-coating provides a significant increase of the tool life of 84%. © 2016 Elsevier Ltd
    view abstract10.1016/j.triboint.2016.08.028
  • Wet Abrasive Jet Machining to Prepare and Design the Cutting Edge Micro Shape
    Biermann, D. and Aßmuth, R. and Schumann, S. and Rieger, M. and Kuhlenkötter, B.
    Procedia CIRP 45 (2016)
    Cutting edge preparation is utilized to increase the stability of cutting tools and to improve the adhesion strength of a subsequent coating. In this context wet abrasive jet machining with a robot guided system allows to prepare local tool areas and to realize a specific design of the cutting edge, as well as advantageous surface qualities. This paper is concerned with the requirements and challenges in preparing and designing the cutting edge micro shape using wet abrasive jet machining. Important factors of the process as well as resultant shapes and topography effects of the machined cutting edges are discussed. © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
    view abstract10.1016/j.procir.2016.02.071
  • An error-adaptive, non-rigid registration method for the analysis of springback in sheet metal forming
    Schweinoch, M. and Sacharow, A. and Biermann, D. and Buchheim, C.
    Key Engineering Materials 651-653 (2015)
    Springback effects, as occuring in sheet metal forming processes, pose a challenge to manufacturing planning: the as-built part may deviate from the desired shape rendering it unusable for its intended purpose. A compensation can be achieved by modifying the forming tools to counteract the shape deviations. A prerequisite to compensation is the knowledge of correspondences (ui, vj), between points ui on the desired and vj on the actual shape. FEM-based simulation software provides means to both virtually predict springback and directly obtain correspondences. In case of experimental prototyping and validation, however, finding correspondences requires solving a registration problem: given a test shape Q (scan points of the as-built geometry) and a reference shape R (CAD data of the desired geometry), a transformation S has to be found to fit both objects. Correspondences between S(Q) and R may then be computed based on a metric. If S is restricted to Euclidean transformations, then S(Q) results in a rigid transformation, where every point of Q is subject to the same translation and rotation. Local geometric deviations due to springback are not considered, often resulting in invalid correspondences. In this contribution, a nonrigid registration method for the efficient analysis of springback is therefore presented. The test shape Q is iteratively partitioned into segments with respect to an error metric. The segments are locally registered using rigid registration subject to regulatory conditions. Resulting discontinuities are addressed by minimization of the deformation energy. The error metric uses information about the deviations computed based on the correspondences of the previous iteration, e.g. maximum errors or changes of the sign. This adaptive per-segment registration allows appropriate correspondences to be determined even under local geometric deviations. © (2015) Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/KEM.651-653.1015
  • Analysis of residual stress states of structured surfaces manufactured by high-feed and micromilling
    Lucas, H. and Denkena, B. and Grove, T. and Krebs, E. and Kersting, P. and Freiburg, D. and Biermann, D.
    HTM - Journal of Heat Treatment and Materials 70 (2015)
    The performance of technological surfaces can be optimized via tailored characteristics according to their specific field of usage. These high performance surfaces are needed for the new technology of Sheet-Bulk Metal Forming (SBMF), which is a combination of sheet metal and bulk forming operations. Due to the high surface loads of bulk forming operations, tool surfaces need to be capable to withstand high stress states. Additional to a high wear resistance, the friction coefficient of these surfaces is an important criterion for the material flow of the sheet material. Surface characteristics can be adjusted by using technologies such as high-feed and micromilling processes resulting in different friction coefficients optimizing functional performance of the tools. In dependency of these different manufacturing processes, different residual stresses are induced into the subsurface of the forming tool. Reliability of residual stress measurements via X-ray diffractometry for microstructured surfaces produced through high-feed milling and micromilling is investigated. © Carl Hanser Verlag GmbH & Co. KG.
    view abstract10.3139/105.110265
  • Determination of the thermal load distribution in internal traverse grinding using a geometric-kinematic simulation
    Schumann, S. and Siebrecht, T. and Kersting, P. and Biermann, D. and Holtermann, R. and Menzel, A.
    Procedia CIRP 31 (2015)
    During grinding processes, numerous grains interact with the workpiece material producing mechanical and thermal loads on the surface. In the field of thermal simulation of grinding processes, a widely used approach is to substitute numerous cutting edges by a single moving distributed heat source of a specific geometrical shape referring to the theory of Carslaw and Jaeger. This heat source is then moved across the modelled workpiece according to the specific kinematics of the grinding process. The geometrical shape of the substituted heat source can usually be determined using different approaches, e. g., predefined distribution functions or, more precisely, based on measurements of the shear stress within the contact zone. Referring to the state of the art, it is not possible to measure the shear stress within the contact zone during internal traverse grinding with roughing and finishing zone because of its very complex engagement conditions and the non-rectangular shape of its contact zone. In this work, a novel approach to determining a heat source distribution based on a geometric-kinematic simulation for internal traverse grinding is presented. This simulation identifies the ideal geometrical interaction of workpiece and grinding wheel. For this purpose, the specific material removal rate for each grain is calculated and accumulated with respect to the contact zone resulting in a three-dimensional thermal load distribution. This heat source can be used in finite element simulations to determine the thermal load on the workpiece. © 2015 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2015.03.020
  • Development of an automatic modal pendulum for the measurement of frequency responses for the calculation of stability charts
    Brüggemann, T. and Biermann, D. and Zabel, A.
    Procedia CIRP 33 (2015)
    In order to fully utilize a machine tool and to identify its natural frequencies, modal analysis can be performed. This provides information about the vibration characteristics of the machine structure during the machining process. In this article, an optimization of experimental modal analysis will be presented. The classical measurement chain to perform a modal analysis is always based upon the principle of excitation, signal transmission, signal detection, and signal analysis of results. The conventional method, wherein the excitation is effected by a modal hammer and the signal detection is done by an acceleration sensor, is now replaced by a process in which excitation is achieved via an automated modal pendulum and the signal detection by means of laser or acceleration. Within the framework of this research, there are two key elements that will be discussed in detail. The first element includes the motivation for the development of the pendulum and the aspired improvements of the new model. A prototype is tested and its performance is valuated. The second key element represents an experimental analysis of the performance, including a comparison between the conventional modal hammer and the developed modal pendulum. Here it should be shown that the repeatability of the hammer strikes of the pendulum is significantly higher than that of the conventional hammer. In addition, the adjustability of the force excitation is to be ensured. © 2014 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2015.06.090
  • Evaluation of different approaches for modeling phase transformations in machining simulation
    Schulze, V. and Uhlmann, E. and Mahnken, R. and Menzel, A. and Biermann, D. and Zabel, A. and Bollig, P. and Ivanov, I.M. and Cheng, C. and Holtermann, R. and Bartel, T.
    Production Engineering 9 (2015)
    Presently, the main mechanism for phase transformations in machining of steels is not absolutely clear and is still subject to research. This paper presents, three different approaches for modeling phase transformations during heating in machining operations. However, the main focus lies on two methods which can be classified into a stress related method and a thermal activation related method for the description of austenitization temperature. Both approaches separately showed very good agreements in the simulations compared to the experimental validation but were never compared in a simulation. The third method is a pre-calculated phase landscape assigning the transformation results based on a micro-mechanically motivated constitutive model to the workpiece in dependence on the temperature and strain history. The paper describes all three models in detail, and the results are also presented and discussed. © 2015, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0618-7
  • Experimental analysis of cutting forces in microdrilling of austenitic stainless steel (X5CrNi18-10)
    Patra, K. and Anand, R.S. and Steiner, M. and Biermann, D.
    Materials and Manufacturing Processes 30 (2015)
    This article presents an experimental investigation on microdrilling of austenitic stainless steel which is a difficult material for machining because of its properties like high strain-hardening rate, low thermal conductivity, and high fracture toughness. Microholes are produced on X5CrNi18-10 austenitic stainless steel workpiece using 0.5 mm diameter solid carbide microdrills. Two factors (cutting speed and feed) and three levels (low-center-high) full-factorial design of experiment are performed. Response surface methodology is used to developed mathematical models (quadratic and bilinear regression models) for cutting forces in microdrilling. The experimental analysis shows that feed affects the cutting force components (radial and thrust) significantly. Additionally, it also shows that there are only minor effects from cutting speed, square of cutting speed, square of feed and product of speed, and feed on the cutting forces. Finally, the optimized cutting conditions are proposed for minimum cutting forces. © 2015 Taylor & Francis Group, LLC.
    view abstract10.1080/10426914.2014.941867
  • Experimental investigation of tool wear and chip formation in cryogenic machining of titanium alloys
    Biermann, D. and Abrahams, H. and Metzger, M.
    Advances in Manufacturing 3 (2015)
    Titanium alloys are one of the most important design materials for the aircraft industry. The high strength-to-density-ratio and the compatibility with carbon fibre reinforced plastic are the reasons for a raising application in this field. The outstanding properties lead to challenging machining processes. High strength and low heat conductivity affect high mechanical and thermal loads for the cutting edge. Thus, the machining process is characterized by a rapid development of tool wear even at low cutting parameter. To reach a sufficient productivity it is necessary to dissipate the resulting heat from the cutting edge by a coolant. Therefore the cryogenic machining of two different titanium alloys is investigated in this work. The results point out the different behavior of the machining processes under cryogenic conditions because of the reduced thermal load for the cutting tool. According to this investigation, the cryogenic cooling with CO2 enables an increase of the tool life in comparison to emulsion based cooling principles when machining the α+β-titanium alloy Ti-6Al-4V. The machining process of the high strength titanium alloy Ti-6Al-2Sn-4Zr-6Mo requires an additional lubrication realized by a minimum quantity lubrication (MQL) with oil. This combined cooling leads to a smoother chip underside and to slender shear bands between the different chip segments. © 2015, Shanghai University and Springer-Verlag Berlin Heidelberg.
    view abstract10.1007/s40436-015-0122-5
  • Experimental investigations on single-lip deep hole drilling of superalloy Inconel 718 with small diameters
    Biermann, D. and Kirschner, M.
    Journal of Manufacturing Processes 20 (2015)
    Recent trends in downsizing, as well as miniaturization of components, increase the importance of deep hole drilling with small diameters in various industrial applications. For the manufacturing of deep holes, many processes are used. In addition to mechanical cutting, processes based on thermal material removal mechanisms like electrical discharge machining (EDM), laser drilling and electron-beam drilling are established. Whereas non-mechanical processes can be used for the machining of extremely hard and high-strength materials, substantial disadvantages are the restrictions in the realizable hole diameter and depth dimensions, the long production times, the requirement for special-purpose machinery, as well as the limited bore hole quality. In the aerospace industry, where nickel-based superalloys are widespread, high requirements lie on the surface integrity due to high stress loads during operation. Hence, the major drawback of these non-mechanical processes is the alteration of the subsurface zone, which could affect the part safety. In contrast, the mechanical machining of nickel-based superalloys is extremely difficult due to material properties such as high strength, high tendency to work hardening and low thermal conductivity which results in increased mechanical tool loads and heavy abrasive and adhesive tool wear. An additional challenge is constituted by the chip removal and the unfavorable ratio of cutting edge rounding and undeformed chip thickness caused by the limitation in the feed rates, if deep hole drilling with small diameters and high-length-to-diameter ratios of difficult-to-cut materials like nickel-based superalloys is required. Up to now, the use of standard tool geometries in small diameter single-lip deep hole drilling of Inconel 718 has not been productive and leads to limited process stability and drilling lengths as well as insufficient bore hole quality. Concerning this matter, this paper presents a process adaption using a tailored cutting edge design to accomplish the predominant challenges. Substantial analysis on gun drilling in Inconel 718 regarding mechanical tool loads, chip formation, the tool wear, as well as bore hole quality will be presented. © 2015 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.
    view abstract10.1016/j.jmapro.2015.06.001
  • Experimental verification of a benchmark forming simulation
    Landkammer, P. and Loderer, A. and Krebs, E. and Söhngen, B. and Steinmann, P. and Hausotte, T. and Kersting, P. and Biermann, D. and Willner, K.
    Key Engineering Materials 639 (2015)
    Forming of near-net-shaped and load-adapted functional components, as it is developed in the Transregional Collaborative Research Centre on Sheet-Bulk Metal Forming SFB/TR 73, causes different problems, which lead to non-optimal manufacturing results. For these high complex processes the prediction of forming effects can only be realized by simulations. A stamping process of pressing eight punches into a circular blank is chosen for the considered investigations. This reference process is designed to reflect the main aspects, which strongly affect the final outcome of forming processes. These are the orthotropic material behaviour, the optimal design of the initial blank and the influences of different contact and friction laws. The aim of this work is to verify the results of finite element computations for the proposed forming process by experiments. Evaluation methods are presented to detect the influence of the anisotropy and also to quantify the optimal blank design, which is determined by inverse form finding. The manufacturing accuracy of the die plate and the corresponding roughness data of the milled surface are analysed, whereas metrological investigations are required. This is accomplished by the help of advanced measurement techniques like a multi-sensor fringe projection system and a white light interferometer. Regarding the geometry of the punches, micromilling of the die plate is also a real challenge, especially due to the hardness of the high-speed steel ASP 2023 (approx. 63 HRC). The surface roughness of the workpiece before and after the forming process is evaluated to gain auxiliary data for enhancing the friction modelling and to characterise the contact behaviour. © 2015 Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/KEM.639.251
  • High-feed milling of tailored surfaces for sheet-bulk metal forming tools
    Hense, R. and Wels, C. and Kersting, P. and Vierzigmann, U. and Löffler, M. and Biermann, D. and Merklein, M.
    Production Engineering 9 (2015)
    The increasingly investigated and applied production process sheet-bulk metal forming (SBMF) has novel requirements for the forming tools, e.g., the need of an adaptive material flow at different areas of the tool for an adequate form filling. One new method to realize different, defined tribological conditions are tailored surfaces (TS). During the design of forming tools, it is imperative to have profound knowledge about the tribology between the tool and the workpiece. This article introduces structuring with high-feed milling tools as one possibility for influencing the material flow during forming processes and presents a ring-compression test for the quantification of the tribological conditions, which is adapted for SBMF. On the basis of various machined structures, surface parameters are analyzed to identify a correlation with the friction coefficient to gain knowledge about the mechanisms of TS and to be able to choose structures according to the needs of SBMF processes. © 2014, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-014-0597-0
  • Influence of surface modifications on friction, using high-feed milling and wear resistant PVD-coating for sheet-metal forming tools
    Biermann, D. and Freiburg, D. and Hense, R. and Tillmann, W. and Stangier, D.
    Key Engineering Materials 639 (2015)
    Increasing technological requirements, as well as the demand for an efficient production demands high performance materials and enhanced manufacturing processes. The development of a new manufacturing process, sheet-bulk metal forming (SBMF), is one approach to produce lightweight forming parts with an increased number of functional properties while, at the same time, combining the advantages of sheet and bulk metal forming. For SBMF processes, the specific adjustment of the friction between tool and workpiece for a specifically designed material flow, which is called tailored friction, is of great importance. The reduction of friction is essential in order to ensure a homogeneous forming zone. However, a higher friction can be used to control the material flow to increase the local thickness of the work piece for additional functional integration. This paper shows the development of surface structures for SBMF tools by means of high-feed milling. Process parameters like the tilt angle or the feed are varied to influence the surface parameters of the structures, which results in different tribological properties of the forming tool. The structured surfaces are subsequently coated with a wear resistant CrAlN coating, processed by a magnetron-sputtering process (PVD) to enhance the lifetime and performance of the forming tool. Finally, a ring compressing test is used to investigate the tribological behavior of the coated structures. © 2015 Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/KEM.639.275
  • Influence of the handling parameters on residual stresses of HVOF-sprayed WC-12Co coatings
    Selvadurai, U. and Hollingsworth, P. and Baumann, I. and Hussong, B. and Tillmann, W. and Rausch, S. and Biermann, D.
    Surface and Coatings Technology 268 (2015)
    In this research work HVOF WC-12Co coatings were deposited on C45 steel (1.0503) substrates. Unfavorable residual stresses can lead to delamination and spallation and thus have to be avoided by optimizing the handling parameters. This study investigates the influence of the following handling parameters: substrate temperature, number of overruns, stand-off distance, track pitch, and gun velocity on the residual stress and hardness. Additionally, the effect of post-treating the coating by means of surface grinding was determined. For the HVOF spraying experiments, fine agglomerated and sintered WC-12Co powders (2-10. μm) with WC particles in the submicron range (400. nm) were chosen. It was determined that alterations of these handling parameters had significant effects on the residual stress and the hardness. © 2014 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2014.11.055
  • Influence of the production process on the deformation and fatigue performance of friction drilled internal threads in the aluminum alloy 6060
    Wittke, P. and Liu, Y. and Biermann, D. and Walther, F.
    Materials Testing 57 (2015)
    Aluminum alloys are used for enhancement of dynamic range, resource optimization and emission reduction in many fields of traffic engineering, whereby aluminum components are manufactured by means of welded, adhesive and screw joints. Friction drilling, as forming process with subsequent manufacturing of threads, offers the opportunity to produce an internal thread in lightweight profiles with a usable thread depth larger than the profile thickness, making use of local material expansion. Moreover, the direct manufacturing offers a huge potential for time and cost saving in comparison to conventional thread machining. Microstructural characterization of mechanical properties of EN AW-6060 internal threads, both in profile and bulk material specimens, was carried out using tensile tests and fatigue tests in the tensile loading range. A comparison was made between the manufacturing techniques tapping, thread forming and thread milling. The maximum tolerable loads of the profile specimens are about 50 % lower in the quasi-static range and about 25 % lower in the cyclic range in comparison to bulk material specimens. Formed threads show the best and cut threads the worst mechanical properties which were correlated with the production-related profile qualities and changes in microstructure. Multiple step tests prove that the fatigue limit of aluminum internal threads, validated in single step tests until 10(7) cycles, can be reliably estimated by means of plastic strain.
    view abstract10.3139/120.110712
  • Investigations on the formation of straightness deviation in MQL deep-hole drilling of thin-walled aluminium components: Experimental and simulation-based analysis of thermomechanical effects in deep-hole drilling using single-lip drills and twist drills
    Biermann, D. and Iovkov, I.
    Production Engineering 9 (2015)
    One of the most challenging machining operation, particularly with regard to the difficult chip evacuation, is the deep-hole drilling process. Due to the high length-to-diameter ratio of the drill holes and of the tools no complete dry machining is possible, thus minimum quantity lubrication is used to provide a lubrication film at the contact surface of the tribological partners and to ensure a reliable chip removal capability. This paper presents a fundamental comparison of the in-process heat input into the workpiece and the resulting straightness deviations for two different tool concepts-a single-lip drill and a twist drill. In particular, the deep-hole drilling of components with small wall thicknesses, down to a minimum value of sw = 1mm, was analysed to gather information about the mechanisms leading to straightness deviations. Due to the conclusions, particularly using a single-lip drill, a novel experimental approach for the determination of the force distribution over the drill radius was developed. It enables the incremental force measurement along the cutting edge and has been used to generate input data for a finite element analysis of the tool deflection and the contact conditions between tool and workpiece. The results indicate that the single-lip drill is a competitive alternative to the twist drill, but the asymmetric cutting edge design and the required guide pad support limit its productivity, in particular with regard to the heat input and the straightness deviation in the manufacturing of drill holes in thin-walled workpieces. © 2015, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0632-9
  • Investigations on the thermal workpiece distortion in MQL deep hole drilling of an aluminium cast alloy
    Biermann, D. and Iovkov, I.
    CIRP Annals - Manufacturing Technology 64 (2015)
    Dry machining is frequently applied in cutting operations, in order to reduce the energy consumption and the production costs. In deep hole drilling operations minimum quantity lubrication (MQL) is used to obtain a reliable chip evacuation, since completely dry machining is not feasible. Due to the low cooling effect of MQL, the drilling process generates a high thermal load on the workpiece, which leads to thermally induced workpiece deformations. This paper presents fundamental experimental investigations on the workpiece temperature, the resulting in-process deformations and the achievable straightness accuracy of the borehole. The investigations focus on two different strategies for enhancing the deep hole drilling using MQL. Initially, a high-feed process guiding is introduced, in order to obtain a higher productivity and to reduce the heat input into the workpiece. The second approach is a novel radial spindle compensation, which performs a directional control of the straightness deviation of the deep hole. © 2015 CIRP.
    view abstract10.1016/j.cirp.2015.04.072
  • Model-based multi-objective optimization: Taxonomy, multi-point proposal, toolbox and benchmark
    Horn, D. and Wagner, T. and Biermann, D. and Weihs, C. and Bischl, B.
    Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 9018 (2015)
    Within the last 10 years, many model-based multi-objective optimization algorithms have been proposed. In this paper, a taxonomy of these algorithms is derived. It is shown which contributions were made to which phase of the MBMO process. A special attention is given to the proposal of a set of points for parallel evaluation within a batch. Proposals for four different MBMO algorithms are presented and compared to their sequential variants within a comprehensive benchmark. In particular for the classic ParEGO algorithm, significant improvements are obtained. The implementations of all algorithm variants are organized according to the taxonomy and are shared in the open-source R package mlrMBO. © Springer International Publishing Switzerland 2015
    view abstract10.1007/978-3-319-15934-8_5
  • Modeling and optimization of machining problems
    Biermann, D. and Kersting, P. and Wagner, T. and Zabel, A.
    Springer Handbook of Computational Intelligence (2015)
    In this chapter, applications of computational intelligencemethods in the field of production engineering are presented and discussed. Although a special focus is set to applications in machining, most of the approaches can be easily transferred to respective tasks in other fields of production engineering, e.g., forming and coating. The complete process chain of machining operations is considered: The design of the machine, the tool, and the workpiece, the computation of the tool paths, the model selection and parameter optimization of the empirical or simulation-based surrogate model, the actual optimization of the process parameters, the monitoring of important properties during the process, as well as the posterior multicriteria decision analysis. For all these steps, computational intelligence techniques provide established tools. Evolutionary and genetic algorithms are common networks. Fuzzy logic represents an intuitive way to formalize expert knowledge in automated decision systems. © Springer-Verlag Berlin Heidelberg 2015.
    view abstract10.1007/978-3-662-43505-2_59
  • Modeling of surface location errors in a multi-scale milling simulation system using a tool model based on triangle meshes
    Siebrecht, T. and Kersting, P. and Biermann, D. and Odendahl, S. and Bergmann, J.
    Procedia CIRP 37 (2015)
    Simulation systems are used to optimize milling processes by analyzing surface location errors, which can be predicted by combining various modeling techniques in a multi-scale way. In order to visualize surface location errors, a multi-dexel representation of the workpiece can be used. The application of a triangle mesh representation of the tools to cut the workpiece model is presented, which results in a higher accuracy of the predicted surface location errors in comparison to a Constructive-Solid-Geometry-(CSG)-based approach. Both models are evaluated by simulating a milling process and the simulation results are validated by comparing them to experimental results. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.
    view abstract10.1016/j.procir.2015.08.064
  • Modelling and simulation of Internal Traverse Grinding: bridging meso- and macro-scale simulations
    Holtermann, R. and Menzel, A. and Schumann, S. and Biermann, D. and Siebrecht, T. and Kersting, P.
    Production Engineering 9 (2015)
    In this work, we focus on the computational bridging between the meso- and macro-scale in the context of the hybrid modelling of Internal Traverse Grinding with electro-plated cBN wheels. This grinding process satisfies the manufacturing industry demands for a high rate of material removal along with a high surface quality while minimising the number of manufacturing processes invoked. To overcome the major problem of the present machining process, namely a highly concentrated thermal load which can result in micro-structural damage and dimension errors of the workpiece, a hybrid simulation framework is currently under development. The latter consists of three components. First, a kinematic simulation that models the grinding wheel surface based on experimentally determined measurements is used to calculate the transient penetration history of every grain intersecting with the workpiece. Secondly, an h-adaptive, plane-strain finite element model incorporating elasto-plastic work hardening, thermal softening and ductile damage is used to simulate the proximity of one cBN grain during grinding and to capture the complex thermo-mechanical material response on a meso-scale. For the third component of the framework, the results from the preceding two simulation steps are combined into a macro-scale process model that shall in the future be used to improve manufacturing accuracy and to develop error compensation strategies accordingly. To achieve this objective, a regression analysis scheme is incorporated to approximate the influence of the several cutting mechanisms on the meso-scale and to transfer the homogenisation-based thermo-mechanical results to the macro-scale. © 2015, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0613-z
  • Modelling, simulation and compensation of thermal effects for complex machining processes: The priority programme 1480 "CutSim"
    Biermann, D. and Iovkov, I.
    Production Engineering 9 (2015)
    This special issue was initiated by the priority programme 1480 "Modelling, simulation and compensation of thermal effects for complex machining processes" and presents current investigations, new approaches and relevant results with regard to the specific topic. In addition to the contributions from the priority programme, this issue contains selected publications, which complement the substantial overview of novel developments in the area of heat source identification, modelling, simulation, minimisation and compensation of thermal effects in machining operations. © 2015, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0634-7
  • Planning and optimisation of manufacturing process chains for functionally graded components.Part 2: case study on self-reinforced thermoplastic composites
    Biermann, D. and Gausemeier, J. and Heim, H.-P. and Hess, S. and Petersen, M. and Ries, A. and Wagner, T.
    Production Engineering 9 (2015)
    In this sequel paper, the previously presented framework for the planning and optimisation of functionally graded components Biermann et al. (Prod Eng Res Dev 7(6):657-664, 2013) is applied within a case study. In addition to the application, the implementational infrastructure of the framework is provided and the preliminaries for applying the framework to the respective production system are presented. Hence, the practical realisation of the models and methods is documented. In the context of the case study, each step of the planning process is demonstrated in a visually assisted way. These visualisations are based on the specific steps of the wizard guiding the planner through the framework. As a central contribution, the specification of a non-trivial gradation and the planning of the corresponding process chain by means of the planning framework are demonstrated. © 2015, German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-015-0610-2
  • Reciprocating sliding wear of case-hardened spheroidal cast iron against 100Cr6 under boundary lubrication
    Stickel, D. and Goeke, S. and Geenen, K. and Huth, S. and Theisen, W. and Biermann, D. and Fischer, A.
    Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 229 (2015)
    Today cast iron with spheroidal graphite is used in a wide range of applications with a high production capacity per year. Due to optimized and well-controlled casting technology, the production of ductile cast iron became economic in such way that ductile cast iron replaced cast or wrought steel in many machinery components like crankshafts, piston rods, and engine mounts. These examples represent technical tribosystems of the automobile industry. Here, current political, economic, and ecological guidelines also demand downsizing combined with high power densities in order to minimize internal friction and reduce fuel consumption and satisfying CO2-emission limits. These guidelines can change the tribological loads and, therefore, result in more severe conditions. One example is the shift of the lubrication regime from hydrodynamic to mixed or boundary lubrication for larger periods of time. In these regimes, the applied load is partially or fully carried by the asperities. Still the need for maintaining as low as possible wear towards the ultra-mild sliding wear regime an integral approach is needed, which has to regard contact conditions, surface topography, interface chemistry, and sub-surface properties. One way to low wear can aim at lowering the run-in phase by e.g. optimizing the topography by means of adjusted machining processes. For this study, reciprocating sliding wear tests were conducted with grinded, milled, polished, and finished samples of case-hardened spheroidal cast iron slid against a 100Cr6 ball of a 5mm radius. The boundary lubrication was provided by a commercial combustion engine lubricant at 80°C. After predefined test cycles, 3D surface topographies were measured by means of confocal white-light microscopy within each wear test in order to analyse the development of the contact conditions over time. In combination with the measured forces and displacements, the tribological loads are calculated by means of a 3D elastic-ideal plastic contact model. Additionally the wear mechanism was analyzed by means of scanning electron microscopy. The overall wear rates and the coefficients of friction depend strongly on the initial surface topography and, therefore, on the machining process. This is also true for the development of a reaction layer (tribomaterial) allowing for ultra-mild siding wear even under boundary lubrication. © IMechE 2015.
    view abstract10.1177/1350650115576245
  • Simulation of MQL deep hole drilling for predicting thermally induced workpiece deformations
    Biermann, D. and Blum, H. and Frohne, J. and Iovkov, I. and Rademacher, A. and Rosin, K.
    Procedia CIRP 31 (2015)
    The resulting thermomechanical load on the workpiece in deep hole drilling operations using minimum quantity lubrication (MQL) induces a strong in-process deflection of the machined component and can cause an insufficient accuracy of the produced hole. Also subsequent machining operations can be affected by the thermoelastic component of this deformation, which remains within the workpiece after the drilling process. Due to the comparatively long main time of typical deep hole drilling operations the thermomechanical simulation of commonly complex machined parts is challenging. In this paper, a fast finite-element approach using massive parallel solution methods is presented and validated for different wall thickness situations. © 2015 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2015.03.038
  • Thermally sprayed finestructured WC-12Co coatings finished by ball burnishing and grinding as an innovative approach to protect forming tools against wear
    Tillmann, W. and Hollingsworth, P. and Baumann, I. and Hiegemann, L. and Weddeling, C. and Tekkaya, A.E. and Rausch, S. and Biermann, D.
    Surface and Coatings Technology 268 (2015)
    The forming of high-strength steel sheets offers novel possibilities to produce lightweight structural parts with a high stiffness for the aircraft and automotive industries. However, the employment of such sheet materials leads to intense wear and thus reduces the lifetime of forming tools. At the same time, the requirements concerning their performance, their geometrical complexity, and their shape accuracy have been significantly increased. To counteract this problem, the tools are either treated by different thermo-chemical processes (e.g. hardening, nitriding) or are coated using thin film techniques such as PVD or CVD. In this study, thermal spraying is presented as a cost efficient and more flexible approach to protect the surface of forming tools against wear. For this purpose, planar samples as well as cylindrical deep drawing dies were coated by means of the high velocity oxy-fuel (HVOF) flame spraying technique, utilizing a fine WC-12Co powder (agglomerate size 2-10. μm) with a carbide size of 400. nm. Prior to the coating operation, a comprehensive parameter optimization was performed based on the statistical design of experiments (DOE) to achieve coatings with improved mechanical and tribological properties. The planar samples were used to ascertain the sliding and rolling wear behavior within two standardized test methods (Ball-on-Disc and Taber Abraser tests). The coated dies were smoothened by ball burnishing as well as grinding and afterwards evaluated within the deep drawing of high strength (HC380LA) steel sheets. In addition, the results were compared to those achieved with an uncoated conventional cold work steel die, which is commonly employed for this operation. In contrast to the cold work steel, both coated dies, the ball burnished as well as the ground die, showed a significantly better wear performance after the forming of 10,000 parts. © 2014 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2014.06.039
  • Tribological investigation of bionic and micro-structured functional surfaces
    Tillmann, W. and Stangier, D. and Hagen, L. and Biermann, D. and Kersting, P. and Krebs, E.
    Materialwissenschaft und Werkstofftechnik 46 (2015)
    An established concept adjusting tribological properties and for increasing the wear resistance is presented by coatings. In addition to the material adaption of surfaces, there are efforts of applying structures on tool active parts in order to allow a further adjustment on the property profile. For this reason, the presented article investigates the influence of bionic and technologically textured surfaces on the friction and wear behavior with and without near-net shaped wear-resistant PVD coatings. Based on the example of nature, a honeycombed surface structure discovered on the head of scarab beetles as well as a dimple structure optimized for the manufacturing time were transferred on HSS steel by means of micro-milling. The analyses focus on the influence of the surface structures, the effects of PVD coatings and their interactions on the friction and wear behavior. The investigations show that the tribological properties depend on each surface structure and the material pairing. Both the technological and the bionic structures show a reduction of the friction coefficient in combination with the material pairing 100Cr6 and WCCo compared to polished samples. Furthermore, it is shown that the CrAlN coating has no influence on the friction behavior, but rather leads to the desired increase in the wear resistance. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
    view abstract10.1002/mawe.201500434
  • Wear behavior of bio-inspired and technologically structured HVOF sprayed NiCrBSiFe coatings
    Tillmann, W. and Hagen, L. and Stangier, D. and Laemmerhirt, I.-A. and Biermann, D. and Kersting, P. and Krebs, E.
    Surface and Coatings Technology 280 (2015)
    Surface modification by means of textured structures can largely enhance the tribological and wear behavior of components and tools under various environmental conditions. Continuous developments in machining processes, such as the micromilling technology, can be used to manufacture fine-scaled structures on hardened steel tool surfaces. Thus, the adjusted friction behavior, which can affect the tendency of a material to adhere to the surface, is compensated by the small number of contact points between the friction partner and the surface. Accordingly, anisotropic friction properties of such structures can lead to a locally different wear behavior. In this study, a NiCrBSiFe self-fluxing alloy is thermally sprayed onto specimens made of AISI M2 high-speed steel (HSS). Technological and bionic surface structures were applied on thermally sprayed and laser remelted substrates. Based on ball-on-disk tests, the coefficient of friction was determined and compared for different high velocity oxy fuel (HVOF) sprayed NiCrBSiFe coatings and surface textures. These experiments show that functional structures can reduce the coefficient of friction. The bio-inspired surface shows a friction reduction of approximately 35% compared to the as-sprayed and polished sample, and a reduction of 25% when compared to the remelted and smoothened surface. Moreover, the analyzed surface conditions lead to a different wear behavior than the bio-inspired structure, which possesses areas with a reduced oxidational wear and less adhesion when compared to the other surface conditions. © 2015 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2015.08.055
  • A framework for the computer-aided planning and optimisation of manufacturing processes for components with functional graded properties
    Biermann, D. and Gausemeier, J. and Heim, H.-P. and Hess, S. and Petersen, M. and Ries, A. and Wagner, T.
    AIP Conference Proceedings 1593 (2014)
    In this contribution a framework for the computer-aided planning and optimisation of functional graded components is presented. The framework is divided into three modules - the "Component Description", the "Expert System" for the synthetisation of several process chains and the "Modelling and Process Chain Optimisation". The Component Description module enhances a standard computer-aided design (CAD) model by a voxel-based representation of the graded properties. The Expert System synthesises process steps stored in the knowledge base to generate several alternative process chains. Each process chain is capable of producing components according to the enhanced CAD model and usually consists of a sequence of heating-, cooling-, and forming processes. The dependencies between the component and the applied manufacturing processes as well as between the processes themselves need to be considered. The Expert System utilises an ontology for that purpose. The ontology represents all dependencies in a structured way and connects the information of the knowledge base via relations. The third module performs the evaluation of the generated process chains. To accomplish this, the parameters of each process are optimised with respect to the component specification, whereby the result of the best parameterisation is used as representative value. Finally, the process chain which is capable of manufacturing a functionally graded component in an optimal way regarding to the property distributions of the component description is presented by means of a dedicated specification technique. © 2014 American Institute of Physics.
    view abstract10.1063/1.4873887
  • A novel method for chip formation analyses in deep hole drilling with small diameters
    Biermann, D. and Kirschner, M. and Eberhardt, D.
    Production Engineering 8 (2014)
    Recent trends of downsizing and miniaturization of components, e.g. in the automotive industry for the manufacturing of fuel injectors or in the medical industry for the production of bone screws or surgical instruments, increase the importance of mechanical deep hole drilling with small diameters. Unfortunately, there are still some open challenges regarding this process. In addition to the unfavorable ratio of the cutting edge rounding to the achievable feed rates and undeformed chip thicknesses which results in significant mechanical tool loads, the control of the chip formation and the removal constitutes a major difficulty. The slender tool dimensions, especially the small cross sections of the chip flutes, necessitate a favorable chip formation to achieve the required process safety and productivity. Therefore, analyses of the chip formation, when machining difficult-to-cut materials provide the means for an effective process design. This analysis, however, is particularly difficult due to the closed operating zone. Quick-stop devices used for the chip formation analyses so far are limited in the tool diameter respectively the revolution speed. Furthermore the informative value is limited, because a quick-stop test takes a significant time to stop and thus the instantaneous cutting conditions during the tool retraction are altered. To overcome these restrictions, a new method for the analysis of the chip formation in small diameter deep hole drilling is presented in this paper. It is based on the utilization of a high-speed camera and tailored material samples. The experimental set-up and the results of first analyses conducted under minimum quantity lubrication are presented. The chip formation process is analyzed for the single-lip gun drilling of the nickel-based alloy Inconel718 and the bainitic steel 20MnCrMo7. © 2014 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-014-0566-7
  • A procedure for the evaluation and compensation of form errors by means of global isometric registration with subsequent local reoptimization
    Klein, L. and Wagner, T. and Buchheim, C. and Biermann, D.
    Production Engineering 8 (2014)
    Stresses remaining in the component after sheet metal forming processes can result in complex form errors, such as springback and torsions. In order to compensate these process-induced deformations, the local and global deformations have to be analyzed. Hence, an appropriate comparison between the actually manufactured and the target design is required. For this purpose, the surface of the actual workpiece is scanned and the so-obtained scan points have to be assigned to corresponding points of the target shape defined by the workpiece model. From these correspondences, a field of deformation vectors can be computed which represents the basis for the compensation strategy. The task of finding appropriate correspondences is called registration. It is usually solved using rigid transformations, i.e., translation and rotation. Due to the locality, strength and complexity of the deformations, rigid transformations are usually not sufficient. As a more flexible alternative, a procedure for non-rigid registration is presented in this paper. Therein, isometry, i.e., the conservation of distances between corresponding points within an appropriate neighborhood structure, is defined as the objective function. The procedure consists of three steps: definition of the neighborhood structure, global registration, and local reoptimization. The main focus of the paper is set to the latter, where an adapted gradient descent method also allowing projections into the triangles of the target shape is presented and experimentally validated. With these three steps, an assignment between both shapes can be calculated, even for strong local deformations and coarse triangular meshes representing the workpiece model. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0510-2
  • Active brazed ceramic cemented carbide compound drills for machining lamellar graphite cast iron
    Biermann, D. and Kirschner, M. and Maier, H.J. and Bach, F.-W. and Möhwald, K. and Schaup, J.
    Production Engineering 8 (2014)
    The optimum and efficient way of machining is linked to the choice of the most appropriate cutting tool and cutting tool material. High performance cutting ceramics are characterized by excellent hardness properties at elevated temperatures. For this reason, cutting ceramics meet the requirements for machining with high cutting speeds to increase process productivity. Whereas cutting ceramics are widely used in turning and milling operations, their use in drilling processes, using ceramic insert tipped tools, is limited to larger diameter applications due to design restrictions. Beyond small diameters, solid ceramic tools were of negligible interest for industrial applications owing to their excessive tool manufacturing costs. This paper presents a new tool concept which addresses this challenge and permits a more productive machining process for drilling small diameter holes using ceramics as the cutting material. An active brazed compound drill combines the advantageous properties of ceramics and cemented carbide as the cutting tool material and basic holder material, respectively. The investigations presented here describe the manufacturing chain as well as the application of a compound drill, and compares it to a widely used industrial reference tool. © 2014 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-014-0547-x
  • Analysis and simulation of surface topographies in grinding of thermally sprayed coatings
    Rausch, S. and Siebrecht, T. and Kersting, P. and Biermann, D.
    Advanced Materials Research 1018 (2014)
    The abrasive-wear resistance and the lifetime of tribologically stressed free-formed surfaces of forming tools can be increased by thermally sprayed tungsten carbide coatings. In order to improve the surface quality and the shape accuracy, the workpieces must be machined prior to industrial application. A suitable machining process is NC grinding on five-axis machining centers using abrasive mounted points. However, the high hardness of the applied coatings and the small diameter of the utilized tools pose a great challenge for the process design. In order to optimize the grinding process and predict the resulting surface topography, a geometric-kinematic simulation based on the modelling of individual grains using Constructive Solid Geometry techniques was developed. In this paper, the results of fundamental investigations on grinding tungsten carbide coatings and the developed process simulation are presented. © (2014) Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/AMR.1018.91
  • Analysis of the surface roughness obtained in a friction spinning process based on empirical models
    Hess, S. and Lossen, B. and Biermann, D. and Homberg, W. and Wagner, T.
    International Journal of Advanced Manufacturing Technology 74 (2014)
    In this paper, an new way to analyze and empirically model the surface roughness of a flange geometry after a friction spinning process is presented. The friction spinning process is an innovative incremental forming technology. This new process combines thermomechanical friction elements of the friction welding process within a conventional metal spinning process. The friction allows a self-inducted heat generation and as a consequence a defined increase of formability. It is possible to produce multifunctional, complex parts from standard tubes and sheets. The process thus readily meets the demands placed on efficiency and the manufacturability of complex lightweight components. By choosing the appropriate process parameters, e.g., axial feed rate or relative motion, the contact conditions between the tool and the workpiece can be influenced in a defined way. A further advantage is the feasibility of influencing the grain structure and the hardness in a locally defined manner. It offers the possibility to manufacture finished components with the required surface roughness. Since not all parameter settings of the parameters rotation speed, head radius, feed, and tool infeed width lead to a measurable surface of the component, a gradient boosting machine will be used as classifier for predicting the valid areas of the design space. Furthermore, the influence of the tool temperature is taken into account. For the empirical modeling of the spatial distribution of the surface roughness, methods from the design and analysis of computer experiments are employed. © 2014, Springer-Verlag London.
    view abstract10.1007/s00170-014-6066-2
  • Cutting edge geometries
    Denkena, B. and Biermann, D.
    CIRP Annals - Manufacturing Technology 63 (2014)
    Tool life and performance are decisively determined by cutting edge geometry. An appropriate shape of the cutting edge improves wear resistance, tool life and process reliability. This paper reviews major developments in cutting edge preparation technologies and methods of cutting edge characterization. Moreover, the influences of cutting edge geometry on chip formation, material flow, as well as mechanical and thermal loads on the tool are discussed. The essential modeling and simulation approaches are presented. Effects on surface integrity are described. Finally, an overview of important perceptions for prospective research and development in this field is provided. © 2014 CIRP.
    view abstract10.1016/j.cirp.2014.05.009
  • Development and analysis of microstructures for the transplantation of thermally sprayed coatings
    Freiburg, D. and Biermann, D. and Peuker, A. and Kersting, P. and Maier, H.-J. and Möhwald, K. and Knödler, P. and Otten, M.
    Procedia CIRP 14 (2014)
    Thermally sprayed coatings and tribological surfaces are a point of interest in many industrial sectors. They are used for better wear resistance of lightweight materials or for oil retention on surfaces. Lightweight materials are often used in the automotive industry as a weight-saving solution in the production of engine blocks. For this, it is necessary to coat the cylinder liners to ensure wear resistance. In most cases, the coating is sprayed directly onto the surface. Previous research has shown that it is possible to transfer these coatings inversely onto other surfaces [1]. This was achieved with plasma sprayed coatings which were transplanted onto pressure-casted surfaces. These transplanted surfaces exhibited better adhesive strength, smoother surfaces, and lower form deviation compared to directly coated surfaces. Additionally, it was shown that even microstructures of a surface coated by plasma spraying can be transferred to pressure-casted surfaces. This paper presents the development and micromilling of different microstructures for transferring thermally sprayed coatings onto pressure-casted surfaces. In the development process, microstructures with different shapes and aspect ratios as well as thin tribological surfaces are designed in order to evaluate the advantages and limitations of the transplantation process. In subsequent experiments, the micromilling process and a simulation of the coating transplantation are presented and analyzed. © 2014 Published by Elsevier B.V.
    view abstract10.1016/j.procir.2014.03.054
  • Effect of cutting edge preparation of coated tools on their performance in milling various materials
    Bouzakis, K.D. and Bouzakis, E. and Kombogiannis, S. and Makrimallakis, S. and Skordaris, G. and Michailidis, N. and Charalampous, P. and Paraskevopoulou, R. and M'Saoubi, R. and Aurich, J.C. and Barthelmä, F. and Biermann, D. and Denkena, B. and Dimitrov, D. and Engin, S. and Karpuschewski, B. and Klocke, F. and Özel, T. and Poulachon, G. and Rech, J. and Schulze, V. and Settineri, L. and Srivastava, A. and Wegener, K. and Uhlmann, E. and Zeman, P.
    CIRP Journal of Manufacturing Science and Technology 7 (2014)
    The cutting edges of coated tools are commonly treated in separate production steps during tool manufacturing. Various methods can be employed, focusing on the cutting edge strengthening by its rounding or by more complicated geometries including chamfer and optimized tool wedge radius and angles. The efficiency of diverse cutting edge preparations on the wear behaviour of coated tools, in milling different materials, was investigated in the framework of a cooperative project of the Scientific Committee "Cutting" of the International Academy for Production Engineering (CIRP). In this activity twenty academic and industrial partners were involved according to a predefined project plan. © 2014 CIRP.
    view abstract10.1016/j.cirpj.2014.05.003
  • Enhancing the surface integrity of tribologically stressed contacting surfaces by an adjusted surface topography
    Goeke, S. and Biermann, D. and Stickel, D. and Stemmer, P. and Fischer, A. and Geenen, K. and Huth, S. and Theisen, W.
    Procedia CIRP 13 (2014)
    Tribological systems are more and more used under mixed and boundary friction conditions. Typically the running-in phase of a tribological system shows a wear rate which is significantly higher than the wear rate during steady state. Commonly it is assumed that smoother surfaces would lead to lower wear rates. A new approach aims at the shortening of the running-in phase by adjusting the surface topography. Specific topographies resulting from milling, grinding, and honing processes were generated and tribologically tested under lubricated sliding wear conditions. Wear tests showed a distinct influence of the surface topography regarding wear rate and running-in time. © 2014 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2014.04.037
  • Fitting of constitutive material parameters for FE-based machining simulations for functionally graded steel components
    Tiffe, M. and Biermann, D. and Zabel, A.
    Key Engineering Materials 611-612 (2014)
    The composition of different materials and their specific properties like tensile strength and toughness is one way to achieve workpiece characteristics which are tailored to the later application. Another approach is the subsequent local heat treatment of workpieces made of homogeneous materials. However, both ways are costly and go along with several subsequent process steps. Therefore, mono-material workpieces which were manufactured by thermo-mechanical forming processes may provide such tailored properties in the form of functional gradations. Furthermore, the process chain is shortened by the combination of forming and heat treatment, but nevertheless machining processes are still needed for proper workpiece finish. This puts the challenge of varying process conditions due to hardness alterations within a single process step, e.g. turning. In addition to experimental investigations simulative analysis techniques are desired to evaluate mechanical as well as thermal loads on tool and workpiece. In the case of FE-based microscopic chip formation simulations proper material behaviour needs to be determined with respect to material hardness. This paper describes the approach of fitting Johnson-Cook material parameters as a function of workpiece material hardness. In order to achieve realistic stress states within the process zone, this approach considers the yield strength as a linear function of the hardness. It is shown how the hardness influences the cutting conditions and how the Johnson-Cook parameters are identified. Then these parameters are validated in three-dimensional simulations of exterior dry turning by comparison of simulated process forces and chip formation to experimentally achieved ones. © 2014 Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/KEM.611-612.1202
  • Five-axis grinding of wear-resistant, thermally sprayed coatings on free-formed surfaces
    Rausch, S. and Biermann, D. and Kersting, P.
    Production Engineering 8 (2014)
    The abrasive wear resistance of tribologically stressed free-formed surfaces can be increased with thermally sprayed tungsten carbide coatings. In order to improve the surface topographies and shape accuracies, the workpieces must be finished prior to industrial application. A suitable machining process is NC grinding on five-axis machining centres using abrasive mounted points. However, the high hardness of the applied coatings and the small diameter of the utilized tools pose a great challenge for the process design. In this paper both, the results of fundamental investigations on the grinding of tungsten carbide coatings as well as a process optimization for the finishing of a coated forming tool are presented. This includes the heat transfer into the coating and the tool wear during the grinding process as well as the wear behaviour of the coating in dependence of the generated surface topography. In order to achieve a smooth surface, elastic-bonded diamond tools were used during polishing in a multi-stage machining process. © 2014 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-014-0537-z
  • Grinding process simulation of free-formed WC-Co hard material coated surfaces on machining centers using poisson-disk sampled dexel representations
    Siebrecht, T. and Rausch, S. and Kersting, P. and Biermann, D.
    CIRP Journal of Manufacturing Science and Technology 7 (2014)
    Deep drawing tools are used in various production processes. In order to increase the life cycle of these tools, thermally sprayed abrasive-wear resistant WC-Co hard material coatings can be applied. With respect to the shape accuracy and surface quality of the forming tools, the coated surfaces have to be finished. A suitable machining process to meet these conditions is grinding on machining centers. In this paper, a geometric simulation model for this grinding process based on the modeling of individual grains with constructive solid geometry techniques is presented. The workpiece is represented by poisson-disk sampled dexels. Validation experiments show a good match of the simulated and measured process forces in different engagement situations. © 2014 CIRP.
    view abstract10.1016/j.cirpj.2014.01.001
  • Innovative flow drilling on magnesium wrought alloy AZ31
    Biermann, D. and Liu, Y.
    Procedia CIRP 18 (2014)
    This article investigates the research of the new application of flow drilling, a chipless hole-making process, on magnesium wrought alloy AZ31 for expanding the lightweight potential of magnesium. The feasibility of the innovative flow drilling on thin magnesium profiles is investigated. Thrust forces and torque during flow drilling are analyzed. Specimens with two different thicknesses have been studied for flow drilling process. Process temperatures during the process are determined by using a thermal imaging camera. The generation of a joint through tapping and thread forming has been examined. © 2014 Elsevier B.V.
    view abstract10.1016/j.procir.2014.06.133
  • Machining of Lightweight Frame Structures
    Hannich, S. and Bruggemann, T. and Tiffe, M. and Biermann, D. and Zabel, A.
    Proceedings of the International Conference on Manufacturing of Lightweight Components: Manulight 2014 18 (2014)
    In the first part of the presented work the results of research regarding integration of acoustic emission sensor technology during the machining of material compounds will be depicted. Extruded aluminium alloys (AW6060) provide as a matrix material, while functional elements in form of conductive paths and reinforcing elements (1.4310) are embedded. The aim of this research is to detect material transitions precisely and to generate an automatable process controlling. To analyse the acoustic emission signals a real-time capable system is used. The frequency spectrum as well as the root mean square-value will be depicted for the experiments. The second part of the work outlines the development and testing of an automated modal impact hammer to provide an impulse based structural excitation source for experimental modal analysis. The use of this pendulum is to increase the repeatability, to enable the variability of the excitation force and to prevent so called double hits. Therefore it is well suited for frequency response measurements of tools. With these measured data, stability charts can be simulated in further steps. With this the milling tool can be used in the optimum range of parameters. (C) 2014 Elsevier B.V.
    view abstract10.1016/l.procir.2014.06.112
  • Modeling techniques for simulating workpiece deflections in NC milling
    Kersting, P. and Biermann, D.
    CIRP Journal of Manufacturing Science and Technology 7 (2014)
    Due to the time- and position-dependent dynamic behavior of the workpiece, the prediction of process dynamics during the five-axis milling of thin-walled free-formed surfaces is a challenge from the modeling point of view. In this paper, three different techniques for modeling workpiece deflections and their integration into a system for simulating the NC milling process will be discussed by means of analyzing the machining of a turbine blade. © 2013 CIRP.
    view abstract10.1016/j.cirpj.2013.08.002
  • Modelling of tool engagement and FEM-simulation of chip formation for drilling processes
    Tiffe, M. and Biermann, D.
    Advanced Materials Research 1018 (2014)
    Drilling is the most used machining operation in modern manufacturing. Consequently, a high efficiency is desired which can be achieved by proper tool geometries and process conditions. The claim for a high degree of process understanding is met by the attempt to visualize the chip formation on a micro scale, e.g. by the use of the finite element method. While two-dimensional FE-simulations of cutting processes are established 3D is the next step to take for further analysis of the drilling processes. Nevertheless, this puts high challenges to the simulative approach in order to achieve valid results. This paper deals with the modelling and the simulation of drilling operations with respect to tool and workpiece geometry. In order to create an acceptable starting condition it is useful to consider the engagement situation of the tool and the workpiece as an ideal state with a defined uncut chip thickness in front of the cutting edge. This provides shorter calculation times due to earlier steady-state chip formation compared to simulations with workpieces which are modeled with uniform surfaces like planes or cones in the initial state. Therefore, the engagement situation is created by the utilization of a geometric-kinematical modelling technique in which an array of rays and their intersections with a triangular mesh constitute a discrete description of a surface. The obtained set of points is further used for triangulation to generate the workpiece geometry mesh. Finally, finite element simulations of the drilling processes are carried out and are analyzed with respect to drilling torque and feed force. © (2014) Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/AMR.1018.183
  • New production technologies in aerospace industry - 5th machining innovations conference (MIC 2014) drilling of inconel 718 with geometry-modified twist drills
    Beer, N. and Özkaya, E. and Biermann, D.
    Procedia CIRP 24 (2014)
    The drilling process of Inconel 718, a nickel-based superalloy, is very challenging due to the material properties, the operating conditions and the high quality requirements. Carbides within the material matrix cause an excessive amount of abrasive tool wear. Moreover, a large amount of the heat caused by the machining process, especially in drilling, has to be dissipated by the tool and the coolant, due to the low thermal conductivity of Inconel 718. This high thermal load also restricts the cutting speed. The combination of all attributes limits productivity and economic efficiency when drilling Inconel 718 with cemented carbide twist drills. This paper presents a method to adapt twist drills considering the mentioned demands by using geometry-modified tools. The aim is to increase the resistance against abrasive wear and to reduce the thermal loads; so that, tool life and bore quality can be improved. The analysis of the new tool geometry was realized by advanced Computational-Fluid-Dynamics (CFD) simulations. The simulations provide detailed information about the coolant flow and consequently the improved cooling of tool regions which are, on the suggested geometry, exposed to very high thermal loads. Experiments showed that the tool life can be increased by up to 50% in contradiction to a standard twist drill. The improvement on the bore quality was shown by determining the roundness deviation and the average surface roughness. In addition, micro hardness tests and metallurgy preparations were conducted to investigate the surface integrity of the bore surface layer. Although the presented geometry only represents a prototype status, the results are impressive. The tool life and the bore quality have been improved, and the simulations showed clearly that there is a significantly better coolant flow, when using the new geometry. © 2014 The Authors. Published by Elsevier B.V.
    view abstract10.1016/j.procir.2014.07.124
  • Optimization of guide pads for the BTA deep hole drilling of high alloyed steels by microfinishing
    Biermann, D. and Abrahams, H. and Goeke, S.
    Production Engineering 8 (2014)
    The boring and trepanning association deep hole drilling of materials with a high tendency to adhesion, such as high alloyed-steels, is characterized by a poor surface quality of the bore hole. Material particles adhere to the guide pads that are positioned on the circumference of the drill head and that are normally responsible for the outstanding workpiece quality. In order to prevent this mechanism the guide pads were coated with an innovative amorphous and tetrahedral bonded (ta-C)-coating. This coating has a reduced friction coefficient of 0.1 against steel and a hardness coefficient of about 7,000 HV. To use the benefits of this ta-C-coating the pre- and the after-treatment of the uncoated carbide substrate and ta-C-coated guide pads are essential. For these process steps a microfinishing process was carried out as an alternative to the conventional treatment by polishing and brushing. The microfinishing of the uncoated guide pads effects a smooth surface that is necessary for an optimum bonding strength of the ta-C-coating at the carbide substrate. Furthermore the chamfer edge in the lead-in-area is rounded which reduces the mechanical load at this specific area during the process. The finishing process of the coated guide pads reduces the coating defects and improves the friction coefficient. Thus, the wear behavior of the guide pads is improved because of the better friction conditions during the drilling process of high alloyed steels. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0505-z
  • Optimization of thermomechanical processes for the functional gradation of polymers by means of advanced empirical modeling techniques
    Biermann, D. and Hess, S. and Ries, A. and Wagner, T. and Wibbeke, A.
    AIP Conference Proceedings 1593 (2014)
    I In this paper, an optimization procedure for complex manufacturing processes is presented. The procedure is based on advanced empirical modeling techniques and will be presented in two parts. The first part comprises the selection and generation of the empirical surrogate models. The process organization and the design of experiments are taken into account. In order to analyze and optimize the processes based on the empirical models, advanced methods and tools are presented in the second part. These tools include visualization methods and a sensitivity and robustness analysis. Moreover, the obtained surrogate models are used for a model-based multi-objective optimization in order to explore the gradation potential of the processes. The procedure is applied to two thermo-mechanical processes for the functional gradation of polymers - a monoxiale stretching of polycarbonate films and a compression moulding process for polypropylene sheets. © 2014 American Institute of Physics.
    view abstract10.1063/1.4873888
  • Process combination for the manufacturing of deep holes with small diameters
    Kirschner, M. and Heilmann, M. and Biermann, D.
    Advanced Materials Research 907 (2014)
    The industrial relevance of bore holes with small diameters and high length-to-diameter ratios rises with the growing requirements on parts and the tendency of components toward downsizing. Examples are components for medical and biomedical products or fuel injection in the automotive industry. An adapted process design is necessary for the production of deep holes with very small diameters, especially when the conditions at the beginning of the deep hole drilling process are unfavorable. In these applications, a hybrid process consisting of a laser pre-drilling and a single-lip deep hole drilling can shorten the process chain in machining components with nonplanar surfaces, or can reduce tool wear in machining case-hardened materials. In this research, the combination of laser and single-lip drilling processes was realized and investigated for the very first time. In addition, results for the machining of workpieces with non-planar surfaces are presented. © (2014) Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/AMR.907.265
  • Residual stresses in different heat treated workpieces after turning
    Lebsanft, M. and Tiffe, M. and Zabel, A. and Zinn, W. and Biermann, D. and Scholtes, B.
    Advanced Materials Research 996 (2014)
    view abstract10.4028/www.scientific.net/AMR.996.652
  • Simulation of grinding processes using finite element analysis and geometric simulation of individual grains
    Siebrecht, T. and Biermann, D. and Ludwig, H. and Rausch, S. and Kersting, P. and Blum, H. and Rademacher, A.
    Production Engineering 8 (2014)
    The wear-resistance of sheet metal forming tools can be increased by thermally sprayed coatings. However, without further treatment, the high roughness of the coatings leads to poor qualities of the deep drawn sheet surfaces. In order to increase the surface quality of deep drawing tools, grinding on machining centers is a suitable solution. Due to the varying engagement situations of the grinding tools on free-formed surfaces, the process forces vary as well, resulting in inaccuracies of the ground surface shape. The grinding process can be optimized by means of a simulative prediction of the occurring forces. In this paper, a geometric-kinematic simulation coupled with a finite element analysis is presented. Considering the influence of individual grains, an additional approximation to the resulting topography of the ground surface is possible. By using constructive solid geometry and dexel modeling techniques, multiple grains can be simulated with the geometric-kinematic approach simultaneously. The process forces are predicted with the finite element method based on an elasto-plastic material model. Single grain engagement experiments were conducted to validate the simulation results. © 2014 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0524-9
  • Towards the multi-scale simulation of martensitic phase-transformations: An efficient post-processing approach applied to turning processes
    Ostwald, R. and Tiffe, M. and Bartel, T. and Zabel, A. and Menzel, A. and Biermann, D.
    Journal of Materials Processing Technology 214 (2014)
    This work presents an efficient finite element based scheme for the prediction of process properties and especially the material condition of workpiece surfaces after turning. This is achieved by using a database generated with the help of a micromechanically motivated material model - capable of simulating interactions of phase transitions and plasticity - for the efficient post-processing of a macroscopic thermo-mechanically coupled finite element simulation of the turning process. This modelling technique is applied to the martensitic part of a functionally graded workpiece which is produced by thermo-mechanically controlled forging processes. Those workpieces provide locally varying material conditions, which are tailored to the later application. The resulting pre-products have to be turned in order to achieve the desired final workpiece geometry and surfaces. Such processes strongly affect material properties such as hardness and ductility. A deterioration of the functionality of the gradation, i.e. the martensitic surface properties, may occur by generation of residual tensile principal stresses which can occur accompanied by white layer formation. These deteriorations can be avoided by adjusting the process parameters appropriately. Especially the cutting speed is supposed to be on a low level (vc < 80 m/min) to avoid thermally driven formation of a white layer and the generation of tensile residual stresses. It is shown how finite element simulations can give insight into the material interactions and thereby facilitate the support of the process parameter adjustment in order to support efficient and reliable part production in industrial applications. © 2014 Elsevier B.V.
    view abstract10.1016/j.jmatprotec.2014.02.022
  • Virtual process systems for part machining operations
    Altintas, Y. and Kersting, P. and Biermann, D. and Budak, E. and Denkena, B. and Lazoglu, I.
    CIRP Annals - Manufacturing Technology 63 (2014)
    This paper presents an overview of recent developments in simulating machining and grinding processes along the NC tool path in virtual environments. The evaluations of cutter-part-geometry intersection algorithms are reviewed, and are used to predict cutting forces, torque, power, and the possibility of having chatter and other machining process states along the tool path. The trajectory generation of CNC systems is included in predicting the effective feeds. The NC program is automatically optimized by respecting the physical limits of the machine tool and cutting operation. Samples of industrial turning, milling and grinding applications are presented. The paper concludes with the present and future challenges to achieving a more accurate and efficient virtual machining process simulation and optimization system. © 2014 CIRP.
    view abstract10.1016/j.cirp.2014.05.007
  • A comparison of low cost structure-borne sound measurement and acceleration measurement for detection of workpiece vibrations in 5-axis simultaneous machining
    Biermann, D. and Zabel, A. and Brüggemann, T. and Barthelmey, A.
    Procedia CIRP 12 (2013)
    In the field of machining technology the vibration of the system machine, tool and workpiece during processing is the limiting factor of productivity. Therefore the process monitoring of vibration today plays an important role for the real time monitoring of machining processes, as well as for the optimization of simulation models. For monitoring workpiece vibrations, different kinds of strategies are in use. As the piezoelectric acceleration sensors were already field-tested at the department of machining technology (ISF), the use of Contact Emission-Sensors, which are customarily used for stringed instrument tuning, could pose an effective alternative strategy. Proving the possibility of using those sensors, could simplify the future choice of the process monitoring strategy for different machining operations and has cost saving potentials, due to an abbreviated measurement chain. Within this work the workpiece vibration during a 5-axis milling process were detected simultaneously by two monitoring strategies. In these experiments, the detection of vibration by a piezoelectric acceleration sensor was chosen as the reference strategy. The second technique deployed was the measurement of the contact-emission with a common contact microphone. On a milling machine for five-axis simultaneous machining, aluminium shafts were fixed in a three-jaw chuck one-sided and processed with an end mill. The geometry of the milling pockets was varied in the different processing sessions, as well as the feed parameters, in order to obtain both stable and unstable processing. The vibration measurements resulting from the two monitoring strategies were compared in form of time signal and frequency spectrum as well as in the combined form of a 3-dimensional waterfall diagram. Monitoring structure borne noise is an easy, cost-efficient alternative to measures with an acceleration sensor. Delivering reliable results concerning the vibration frequencies, which are multiples of the spindle rotation frequency, this method could be applied for process monitoring. The experiments have shown that the location of the Contact Emission-Sensors has major impact on the quality of results. To implement the Contact Emission-Sensors for this kind of measurements, the sensor must be positioned close to the place of vibration origin taking into account both damping characteristics of all components involved and the way of workpiece clamping.
    view abstract10.1016/j.procir.2013.09.017
  • A novel abrasive blasting process: Abrasive medium classification and CFD simulations
    Özkaya, E. and Bayraktar, E. and Turek, S. and Biermann, D.
    Materialwissenschaft und Werkstofftechnik 44 (2013)
    This study concerns the determination of the significant factors for an innovative deburring process: low pressure abrasive water-jet blasting. The abrasive medium aluminum oxide (Al2O3) is classified according to the individual characteristics of different grain sizes. Then, the particle behavior in the air jet is analyzed with an optical measuring method, Particle Image Velocimetry (PIV); the velocity profile and the particle distribution of the dispersed system are obtained. Computational Fluid Dynamics (CFD) simulations were verified by comparing the experimental and numerical results, and the velocity range for the abrasive particles has been specified. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    view abstract10.1002/mawe.201300124
  • Friction analysis of thermally sprayed coatings finished by ball burnishing and grinding
    Tekkaya, A.E. and Kleiner, M. and Biermann, D. and Hiegemann, L. and Rausch, S. and Franzen, V. and Kwiatkowski, L. and Kersting, P.
    Production Engineering 7 (2013)
    Thermally sprayed coatings offer a promising approach as efficient method to increase the wear-resistance of sheet metal forming tools. However, the roughness of thermally sprayed surfaces is quite high. The use of these coatings for deep drawing tools results in poor sheet surface qualities and low drawing ratios. Because it is suspected that high friction is the reason for the low drawability, hard metal coatings (WC-12Co), deposited by high velocity oxygen fuel flame-spraying, were machined by grinding and ball burnishing to improve their friction behavior and the accuracy of the tool shape. The investigation was conducted by plane strip drawing tests. Strips of high strength steel were mated with these novel and effective coatings at different normal contact pressures and drawing velocities. Uncoated friction elements made of C60 steel were considered as reference during the analysis. The results revealed that coated but unmachined friction elements showed high friction values, which led to scratch marks on the sheet surface after drawing. Applying the finishing processes, the friction coefficient could be reduced significantly. Additionally, deep drawing tests were carried out to determine the drawing ratio for coated, unmachined as well as for processed, coated dies. Thermally sprayed and ball burnished as well as thermally sprayed and ground coatings are feasible for deep drawing. Due to the post treatment, the drawing ratio β = 1.8 was increased to 2.0. This is consistent to the results of the friction tests. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0485-z
  • Improvement of wear resistant thermally sprayed coatings by microfinishing
    Biermann, D. and Goeke, S. and Tillmann, W. and Nebel, J.
    CIRP Annals - Manufacturing Technology 62 (2013)
    To increase the wear resistance of tribologically highly stressed slide faces, thermally sprayed coatings based on tungsten carbide are widely used. In addition to the technological progress in powder metallurgy and coating technology, an improved preparation of the substrate surface increases the fatigue resistance of the coated workpieces. Surfaces machined by short-stroke honing instead of the commonly used abrasive blasting process, show a significantly enhanced interface between the surface and the coating. In addition, the use of diamond as hard cutting material enables the wear resistant coating to be honed and a high surface quality to be generated. © 2013 CIRP.
    view abstract10.1016/j.cirp.2013.03.023
  • In situ qualitative inspection of hole exit delamination at bottom-ply during drilling of woven CFRP epoxy composite laminates
    Faraz, A. and Biermann, D.
    Advanced Engineering Materials 15 (2013)
    Exploiting very high speed digital videography, an in situ examination of the hole exit delamination at the bottom-most ply during drilling holes in the selected woven CFRP epoxy laminates is presented. At the beginning, a rotating elastic bulge of the carbon fibers at the bottom-ply, which is just the impression of the protruding drill chisel edge, was always observed. Following the elastic bulging, a few, initial cracks along the weak fiber/matrix interfaces appeared. Thereafter, tensile failures in the carbon fibers were seen. The exact location of the initiation of these fiber failures specifically depends on the actual drill-hole position with respect to the woven configuration of the bottom-ply. A visual model for the weak interstitial or undulated regions at the bottom-ply is also proposed in this paper, showing the undulating fibers, which are susceptible to mostly tensile failures under the drilling loads. During a sub-completion drilling-phase at the bottom-ply, various cracks were seen to be propagating mostly via linear paths. Also, the exit delamination at the bottom-ply during a sub-completion drilling-phase was always observed as to be divided into various small, independent localized contours - each of which propagated almost independently through within several individual warps/wefts during drill-feed. Also, the shape of each such tiny contour within a single warp/weft was identified as elliptic, which is observed around an entire drill-hole in unidirectional (UD) composites as reported in literature. It was also observed that the overhanging cantilever-like fibers at the bottom-ply are really difficult to cut, once their base-location or their exit delamination contour reaches outside the hole nominal diameter. Moreover, by referring to some very basic cutting angle configurations for the orthogonal trimming of UD-composites as found rarely in archival literature, an illustrative model diagram is also proposed for the drilling of the selected laminate material. This idea is also approximately validated via a few visual observations. The proposed visual model is generally an attempt in correlating the observed peripheral hole quality (delamination) with various instantaneous tool/fiber engagement configurations occurring across the entire drill-hole periphery at the bottom-ply, during the very last drilling-phase. An in-situ examination of hole exit delamination at the bottom-ply during drilling holes in the selected woven CFRP is presented. The advent, accruement and shape-pattern of the exit delamination are discussed via some experimental observations. A few illustrative models are also proposed. An attempt to correlate exit delamination results with the instantaneous cutting angle configurations right at the bottom-ply is also made in this article. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    view abstract10.1002/adem.201200342
  • Indicator-based selection in evolutionary multiobjective optimization algorithms based on the desirability index
    Trautmann, H. and Wagner, T. and Biermann, D. and Weihs, C.
    Journal of Multi-Criteria Decision Analysis 20 (2013)
    In multiobjective optimization, the identification of practically relevant solutions on the Pareto-optimal front is an important research topic. Desirability functions (DFs) allow the preferences of the decision maker to be specified in an intuitive way. Recently, it has been shown for continuous optimization problems that an a priori transformation of the objectives by means of DFs can be used to focus the search of a hypervolume-based evolutionary algorithm on the desired part of the front. In many-objective optimization, however, the computational complexity of the hypervolume can become a crucial part. Thus, an alternative to this approach will be presented in this paper. The new algorithm operates in the untransformed objective space, but the desirability index (DI), that is, a DF-based scalarization, will be used as the second-level selection criterion in the non-dominated sorting. The diversity and uniform distribution of the resulting approximation are ensured by the use of an external archive. In the experiments, different preferences are specified as DFs, and their effects are investigated. It is shown that trade-off solutions are generated in the desired regions of the Pareto-optimal front and with a density adaptive to the DI. The efficiency of the approach with respect to increasing objective space dimension is also analysed using scalable test functions. The convergence speed is superior to other set-based and preference-based evolutionary multiobjective algorithms while the approach is of low computational complexity due to cheap DI evaluations. © 2013 John Wiley & Sons, Ltd.
    view abstract10.1002/mcda.1503
  • Investigation of different hard coatings for micromilling of austenitic stainless steel
    Biermann, D. and Steiner, M. and Krebs, E.
    Procedia CIRP 7 (2013)
    (Micro-)Machining of austenitic stainless steel is highly challenging due to the formation of build-up edges, adhesive tool wear and also the ability for work hardening, the low thermal conductivity, and the high toughness. Here, the application of tool coatings is a suitable method to extend tool life and to improve consequently the overall workpiece quality. Yet the qualification of different tool coatings for micromilling austenitic stainless steel has to be analysed. In this investigation micromilling experiments applying two fluted endmills having a diameter of d = 1 mm with different hard coatings were applied. The austenitic stainless steel X5CrNi18-10 (1.4301) served as the workpiece material. The tool coatings were CrN, TiN, AlCrN, AlTiN and TiAlN. Using a constant set of cutting parameters and the same basic tool geometry, the achievable performance of the different coatings was evaluated in terms of the process forces, the tool wear and the achievable surface quality. The application of a TiAlN and AlCrN coating generated very good results regarding the tool wear. Relating to the surface quality, the AlTiN coating provided the best results. © 2013 The Authors.
    view abstract10.1016/j.procir.2013.05.042
  • Iterative, simulation-based shape modification by free-form deformation of the NC programs
    Sacharow, A. and Odendahl, S. and Peuker, A. and Biermann, D. and Surmann, T. and Zabel, A.
    Advances in Engineering Software 56 (2013)
    In production engineering, there are several applications where the geometry of a designed workpiece has to be modified, e.g., optimization of forming tools during springback compensation in sheet metal forming. In general, the modified shape of the workpiece is given as a mesh and has to be converted to a parametric representation by surface reconstruction before manufacturing. In this paper, a new approach for obtaining small shape modifications by direct deformation of the NC programs is presented. In an iterative process, the CAM data is modified by a free-form deformation and is verified by a milling simulation so that the modified workpiece can be manufactured directly on the basis of the original CAD/CAM data without surface reconstruction. © 2012 Elsevier Ltd. All rights reserved.
    view abstract10.1016/j.advengsoft.2012.11.007
  • Modeling and simulation of heat input in deep-hole drilling with twist drills and MQL
    Biermann, D. and Iovkov, I.
    Procedia CIRP 8 (2013)
    Former investigations on deep-hole drilling using twist drills and MQL indicated that the heat input into the workpiece results not only from the primary thermal load within the machining zone but also from the secondary heating at the borehole wall. In order to determine the primary heat flow into the machined part an experimental setup for drilling devoid of the influence of the borehole wall has been developed. The results show that the machining time is the major factor: the lower the machining time the lower the measured temperature within the workpiece. A finite-element-(FE)-based simulation in consideration of the material removal has been implemented and studied, regarding the process, the FE-mesh and the time discretisation. Based on the reliable parameter, obtained by the discretisation study, a simulation control loop is presented which allows the calculation of the rate of heat flow into the machined part. It is remarkable that due to the material removal the heat flow into the workpiece increases when machining with higher cutting speed and feed values, while the measured and simulated temperature decreases. Copyright © 2013 Elsevier B.V.
    view abstract10.1016/j.procir.2013.06.070
  • Modelling, simulation and experimental investigation of chip formation in internal traverse grinding
    Holtermann, R. and Schumann, S. and Menzel, A. and Biermann, D.
    Production Engineering 7 (2013)
    We present recent developments in modelling and simulation of internal traverse grinding, a high speed machining process which enables both a large material removal rate and high surface quality. We invoke a hybrid modelling framework, including a process scale model, simulations on a mesoscale capturing the proximity of a single cBN grain and an analysis framework to investigate the grinding wheel topography. Moreover, we perform experiments to verify our simulations. Focus in this context is the influence of the cutting speed variation on the grain specific heat generation. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0449-3
  • Multi-objective optimization of hard turning of AISI 6150 using PCA-based desirability index for correlated objectives
    Wonggasem, K. and Wagner, T. and Trautmann, H. and Biermann, D. and Weihs, C.
    Procedia CIRP 12 (2013)
    The turning process, one of the most popular material removal processes in industry, has several performance measures which are usually found to be correlated, such as tool wear, cutting force and surface finish. In order to apply optimization methods, such as the desirability index, the conditional independence assumption is usually made. However, this assumption rarely holds true in real world applications and the optimal solution obtained might be biased towards the performance measures which have strong positive correlations with the others. Despite the fact that the desirability index has been developed and frequently applied in industry for a long time, only a few studies have been carried out to solve optimization problems with correlated objectives. The modified desirability index which provides a solution for integrating the expert's preferences and the correlation information of the performance measures into the overall performance index, the principal component analysis (PCA) based desirability index (DI), has been only recently developed. In this paper, an optimization using the PCA-based DI is demonstrated based on empirical models of hard turning of AISI 6150 steel in which uncertainties are propagated by model errors. The results show that the degree of importance of each performance measure has been adjusted by the integration of the covariance information into the overall performance index.
    view abstract10.1016/j.procir.2013.09.004
  • New coating systems for temperature monitoring in turning processes
    Biermann, D. and Kirschner, M. and Pantke, K. and Tillmann, W. and Herper, J.
    Surface and Coatings Technology 215 (2013)
    High temperature loads in cutting processes can cause high tool wear and damages in the subsurface zone of the workpiece. Especially, the interaction between different cutting parameters affects the thermal loads in the cutting zone. Hence, the knowledge of temperatures in cutting processes is an important factor, and it is the main focus of current investigations. Therefore, this paper deals with an in-process monitoring system for the resulting temperatures in a turning process. In contrast to the investigations performed hitherto, this research deals with a new tool sensor system for temperature measurement. This sensor system is realized by a PVD coating of a Nickel and a Nickel-Chromium layer on the rake face of cutting inserts. On the junction points of this layer system, three thermocouples are deposited. The development of the coating system and the resulting measurement is shown. Additionally, the results are discussed in comparison to thermal imaging system and conventional thermocouples. © 2012 Elsevier B.V.
    view abstract10.1016/j.surfcoat.2012.08.086
  • On the effects of cutting speed and cooling methodologies in grooving operation of various tempers of β-titanium alloy
    MacHai, C. and Iqbal, A. and Biermann, D. and Upmeier, T. and Schumann, S.
    Journal of Materials Processing Technology 213 (2013)
    High strength and its retention at elevated temperatures render titanium alloys highly difficult to cut. Of commonly used titanium alloys, β-alloys are the ones possessing highest values of strength. Higher productivity in machining demands higher cutting speed and its implementation generates even more heat at primary and secondary shear zones. Poor thermal conductivity of titanium causes concentration of excessive heat near the cutting edge, which in turn, leads to rapid damage of cutting tool. The situation, thus, demands application of an innovative cooling methodology that would cause effective removal of heat in order to make implementation of higher cutting speeds viable. The paper describes an experimental investigation carried out to quantify the effects of high levels of cutting speed and the influence of carbon dioxide snow (CO2-snow) as an innovative cooling methodologies in machining of three tempers of β-titanium alloy. A comparison was made among various cooling techniques, which consisted of following: conventional flood emulsion; impingement of jet of CO2-snow at the rake face, the flank face, the rake and flank faces together; and the combination of the CO2-jet and MQL. The comparative effectiveness of each methodology was evaluated in terms of cutting forces, tool wear, and acoustic emission as an indicator to measure differences in terms of the chip morphology. © 2013 Elsevier B.V.
    view abstract10.1016/j.jmatprotec.2013.01.021
  • Oscillator-based approach for modeling process dynamics in NC milling with position- and time-dependent modal parameters
    Biermann, D. and Surmann, T. and Kersting, P.
    Production Engineering 7 (2013)
    Oscillator models provide an efficient approach for simulating the dynamic behaviour of the machine, tool, or workpiece. In their application, however, these models are usually limited to describing the vibration behaviour at one specific position since they do not contain any information about the structure of the machine tool or the workpiece. Additionally, the variation in time dependent parameters caused by the material removal process is not taken into account. In this paper, an adapted model, which takes the position- and time-dependent modal parameters during NC milling into account, is presented and its experimental validation with respect to the machining of thin-walled components is discussed. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0454-6
  • Planning and optimisation of manufacturing process chains for functionally graded components-part 1: Methodological foundations
    Biermann, D. and Gausemeier, J. and Hess, S. and Petersen, M. and Wagner, T.
    Production Engineering 7 (2013)
    Functional gradation denotes a continuous distribution of properties over at least one spatial dimension of a component made of a single material. This distribution is tailored with respect to the later intended application of the component (Biermann et al. in Proceedings of the 1st international conference on thermo-mechanically graded materials, collaborative research centre transregio 30, Verlag Wissenschaftliche Scripten, Auerbach, pp 195-200, 2012). The improved utilisation of the material enables light weight design and a reduced resource consumption, thus offering an alternative for modern composite materials. However, their production requires complex thermo-mechanically coupled manufacturing process chains that increase the effort for the holistic design. To realise the full potential of functional gradation, novel ways for the planning and analysis of the corresponding manufacturing process chains have to be developed. This contribution proposes methods for the description of functionally graded components, as well as the synthetisation and optimisation of their corresponding process chains. The process knowledge, models and methods required are consolidated in a comprehensive planning framework. © 2013 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-013-0490-2
  • Simulation of the NC Milling Process for the Prediction and Prevention of Chatter
    Odendahl, S. and Joliet, R. and Ungemach, E. and Zabel, A. and Kersting, P. and Biermann, D.
    New Production Technologies in Aerospace Industry (2013)
    The main goal in the design of milling processes for components in the aerospace industry is the optimization of productivity while maintainig process stability. These two goals can be conflicting, especially if long tools are required, which are particularly susceptible to vibrations. In order to reduce the number of costly experiments, simulation-based approaches can be used to evaluate generated NC programs beforehand. In this paper, a modeling approach for the detailed simulation of engagement conditions, process forces, and dynamic tool behavior is used to detect instable process conditions. Additionally, an algorithm is presented to change the axial immersion in order to avoid regenerative chatter during milling. To demonstrate the effectiveness of the simulation approach and of the compensation strategy, a comparison is shown between experimental and simulated results and between the workpiece generated by the original and the optimized NC programs.
    view abstract10.1007/978-3-319-01964-2_3
  • Stabilization techniques and a posteriori error estimates for the obstacle problem
    Biermann, D. and Iovkov, I. and Blum, H. and Rademacher, A. and Klein, N. and Suttmeier, F.-T.
    Applied Mathematical Sciences 7 (2013)
    This work deals with a posteriori error estimates for the obstacle problem. Deriving an estimator on the basis of the variational inequal- ity with respect to the primal variable, an inconsistent one is obtained. To achieve consistency, this problem is treated by a Lagrange formalism, which transfers the variational inequality into a saddle point problem. Different techniques to ensure the stability of the discretization and to solve the discrete problems by iterative solvers are studied and com- pared. Numerical tests confirm our results of consistent a posteriori error estimation. © 2013 Dirk Biermann et al.
    view abstract10.12988/ams.2013.39504
  • Turning of high-strength bainitic and quenched and tempered steels
    Biermann, D. and Hartmann, H. and Terwey, I. and Merkel, C. and Kehl, D.
    Procedia CIRP 7 (2013)
    Technological properties of components can benefit from the application of modern steel grades. For example, a reduction of fuel consumption or an improvement in vehicle efficiency can be achieved by using high-tensile bainitic steels in automotive industry in order to increase injection pressure in fuel supply. To take advantages like technological progress, sustainability or cost savings the machinability of these materials has to be investigated in order to prepare for a future industrial use of steels with a bainitic structure. In this paper, turning of the bainitic steel 20MnCrMo7+BY in comparison to the quenched and tempered steels 42CrMo4+QT and 50CrMo4+QT is analysed. © 2013 The Authors.
    view abstract10.1016/j.procir.2013.05.047
  • Abrasive points for drill grinding of carbon fibre reinforced thermoset
    Biermann, D. and Feldhoff, M.
    CIRP Annals - Manufacturing Technology 61 (2012)
    In this study, an approach for using diamond grinding tools to machine holes in epoxy carbon laminates is described. The development of a suitable tool design and the influence of the cutting parameters are presented. With these tools, large total drilling lengths can be achieved without significant grain wear. Analysis of the results shows that the coolant supply can be reduced without exceeding the resin's glass transition temperature. In addition to the experimental results, a process simulation is applied to improve the tool layout and hence to avoid material clogging at the grinding layer. © 2012 CIRP.
    view abstract10.1016/j.cirp.2012.03.096
  • Acquisition of heuristic knowledge for the prediction of the frictional behavior of surface structures created by self-excited tool vibrations
    Breitsprecher, T. and Hense, R. and Hauer, F. and Wartzack, S. and Biermann, D. and Willner, K.
    Key Engineering Materials 504-506 (2012)
    The selective control of the frictional behavior (tailored friction) in metal forming processes is of high importance with regard to technical and economic aspects. This applies especially for the sheet-bulk-metal forming process. Milling with intentionally invoked regenerative tool vibrations can be applied in order to generate structured surfaces with tailored friction properties on the forming tool. These structures affect the formation of lubrication pockets during the forming process which determine the local frictional properties exceedingly. The full potential of this emerging technology can, however, only be revealed if the heuristic and design-relevant knowledge is acquired and provided to the tool-designer already in the early phases of process development. One thing the tool-designer has to specify is the local frictional behavior on the tool surface. But, however, he does not know which milling parameters lead to the necessary surface structures because in most cases he has no expert knowledge in milling, tribology and forming tools. In this paper data mining is used to determine the frictional behavior based on these parameters. The potential of this method in the described context is revealed by the application on data derived from simulation results, both from milling simulations and contact simulations. The latter are performed by using a Halfspace model for rough surface contact. Both approaches for these simulations, the data mining process and the results are explained to the reader. © (2012) Trans Tech Publications.
    view abstract10.4028/www.scientific.net/KEM.504-506.963
  • An experimental study on the groove design for joints produced by hydraulic expansion considering axial or torque load
    Marré, M. and Rautenberg, J. and Tekkaya, A.E. and Zabel, A. and Biermann, D. and Wojciechowski, J. and Przybylski, W.
    Materials and Manufacturing Processes 27 (2012)
    This article presents research work on the influence of the design characteristics of the joint partner elements and especially of grooving and pocketing on the tensile and torsional strength of tubular joints produced by hydraulic expansion when tubes are made of aluminum EN AW-6060. In general, joining of tubular elements can be performed by different methods, but internal expansion presents an interesting alternative to other methods like welding and mechanical forming processes. Commonly, hydraulic expansion is used for the manufacturing of heat exchangers. As a result, time effective and resistant joints must be produced in particular when applying hydraulic expansion in the manufacturing of lightweight structures. © Taylor and Francis Group, LLC.
    view abstract10.1080/10426914.2011.593232
  • Analysis of micro burr formation in austenitic stainless steel X5CrNi18-10
    Biermann, D. and Steiner, M.
    Procedia CIRP 3 (2012)
    This paper presents the results on the analysis of micro-burr formation for slot milling of austenitic stainless steel X5CrNi18-10. Two-fluted submicron grain cemented carbide tools with a diameter of d = 0.5 mm were used. Applying cutting speeds from vc = 100 m/min to vc = 200 m/min and feeds per tooth from fz = 6 μm to fz = 8 μm the influence of these parameters on the burr formation was investigated. Additionally the effect of the lubrication method - minimum quantity lubrication, flood lubrication and bath lubrication - on the burr formation was analysed. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.07.018
  • Cutting edge preparation to enhance the performance of single lip deep hole drills
    Biermann, D. and Wolf, M. and Aßmuth, R.
    Procedia CIRP 1 (2012)
    An improvement in the efficiency of the cutting process requires high tool performance. For the tool performance the microscopic cutting edge shape is very important. By preparing the cutting edge the tool performance can be improved due to the reduction of the cutting edge chipping and the creation of a defined stable edge rounding. In this study, the influence of a cutting edge preparation on the deep hole drilling process is investigated. The aim is to increase the feed rate by a specific cutting edge design. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.04.030
  • Cutting with coated tools: Coating technologies, characterization methods and performance optimization
    Bouzakis, K.-D. and Michailidis, N. and Skordaris, G. and Bouzakis, E. and Biermann, D. and M'Saoubi, R.
    CIRP Annals - Manufacturing Technology 61 (2012)
    Coated tools constitute the majority of the tools applied in material removal processes, rendering the employment of uncoated ones as an exception. A broad growing market of coated cutting tools has been developed. Moreover, numerous material- and manufacturing-engineers have joint their expertise, aiming at developing coatings meeting the needs for processing the most difficult-to-cut materials at the most extreme cutting conditions. The emerging of new workpiece, tool and film materials, the evolution of sophisticated coatings' characterization methods and the continuous need for higher productivity rates, maintain vivid the industrial and scientific interest for further advancing this field. © 2012 CIRP.
    view abstract10.1016/j.cirp.2012.05.006
  • EBSD-Orientation analysis of monocrystalline diamonds used for diamond metal composites - Influence of sample preparation
    Tillmann, W. and Biermann, D. and Weihs, C. and Ferreira, M. and Rautert, C. and Raabe, N.
    Materialwissenschaft und Werkstofftechnik 43 (2012)
    This paper focuses on a new field of application for the EBSD-technique. Generally, EBSD-mappings are performed on different metal alloys used for quality assurance and to get information about the microstructure regarding grain orientation, grain size and distribution. In contrast, the orientation determination of monocrystalline diamond grains with an EBSD system is not a conventional method. Thus, this work describes the EBSD testing sequence in detail and illustrates the preparation of orientation data for a statistical design. Furthermore, dependencies of the sample preparation, alignment to the detector, and the analyzed position on the diamond on the quality of the Kikuchi-patterns, respectively on the indexing rates, have been scrutinized. Finally, the orientation obtained of each tested diamond sample has been utilized in a statistical design to show a direct influence of the crystal orientation on the wear behavior of the diamond grains. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    view abstract10.1002/mawe.201200954
  • Experimental investigation on micromilling of austenitic stainless steel
    Biermann, D. and Steiner, M.
    International Journal of Nanomanufacturing 8 (2012)
    This paper presents the results of experimental investigations on the micro-machinability of the austenitic stainless steel 1.4301 under dry cutting conditions. Two different types of coated carbide micro end-milling cutters with a diameter of d = 1 mm were used. Applying a central composite design for the experimental investigations, the effects of the process parameters cutting speed v c, depth of cut a p, width of cut a e and feed per tooth f z on the process forces were analysed. It was found that the cutting speed v c had nearly no influence on the active force F a. The feed per tooth f z is the major factor influencing the active force F a for the defined parameter range. The achievable surface roughness and the tool wear were analysed as well. Based on the experimental results a range for suitable cutting parameters was identified and a comparison of two different tool designs was done. Copyright © 2012 Inderscience Enterprises Ltd.
    view abstract10.1504/IJNM.2012.047020
  • Grinding of hard-material-coated forming tools on machining centers
    Rausch, S. and Biermann, D.
    Procedia CIRP 1 (2012)
    In this paper, the grinding of hard-material-coated forming tools on a machining center is presented. The coated materials have to be machined mechanically because of the insufficient surface quality and form errors resulting from the thermal spraying processes. During the fundamental investigations two different tungsten carbide coatings have been machined by applying super abrasive grinding tools consisting of four different bond systems. To identify the suitable grinding tools, the process forces and the surface roughness values have been carried out by a screening design of experiments. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.04.069
  • High-performance surface peel grinding on conventional surface grinding machines
    Rausch, S. and Biermann, D.
    Procedia CIRP 1 (2012)
    In this poster paper, a novel grinding process for replacing conventional surface and creep feed grinding processes is presented. This grinding process allows high removal rates in hard machining with flexibility and a good surface finish at the same time. A peel grinding process is conducted with a high workpiece velocity and a high depth of cut, using a conventional surface grinding machine and an electroplated CBN wheel with a custom shape. To validate the efficiency of this process, the process forces and the surface roughness values have been carried out experimentally. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.04.120
  • Improved tool surfaces for incremental bulk forming processes of sheet metals
    Sieczkarek, P. and Kwiatkowski, L. and Tekkaya, A.E. and Krebs, E. and Biermann, D. and Tillmann, W. and Herper, J.
    Key Engineering Materials 504-506 (2012)
    Sheet-bulk metal forming is a process used to manufacture load-adapted parts with high precision. However, bulk forming of sheet metals requires high forces, and thus tools applied for the operational demand have to withstand very high contact pressures, which lead to high wear and abrasion. The usage of conventional techniques like hardening and coating in order to reinforce the surface resistance are not sufficient enough in this case. In this paper, the tool resistance is improved by applying filigree bionic structures, especially structures adapted from the Scarabaeus beetle to the tool's surface. The structures are realized by micromilling. Despite the high hardness of the tool material, very precise patterns are machined successfully using commercially available ball-end milling cutters. The nature-adapted surface patterns are combined with techniques like plasma nitriding and PVD-coating, leading to a multilayer coating system. The effect of process parameters on the resistance of the tools is analyzed experimentally and compared to a conventional, unstructured, uncoated, only plasma nitrided forming tool. Therefore, the tools are used for an incremental bulk forming process on 2 mm thick metal sheets made of aluminum. The results show that the developed methodology is feasible to reduce the process forces and to improve the durability of the tools.© (2012) Trans Tech Publications.
    view abstract10.4028/www.scientific.net/KEM.504-506.975
  • Modeling techniques for the prediction of workpiece deflections in NC milling
    Kersting, P. and Biermann, D.
    Procedia CIRP 2 (2012)
    Due to the characteristics of the milling process, modeling workpiece dynamics during the machining of freeform surfaces is a challenge: The relative movement between the milling tool and the workpiece leads to a variation of the excitation position, and the material removal process results in changing modal parameters of the workpiece. In this paper, an ongoing work is discussed dealing with different modeling techniques for the prediction of workpiece deflections: a finite element model, a particle-based approach, and an oscillator-based technique. These three methods and their integration into a simulation system for the modeling of NC milling are presented and discussed by simulating the machining of a turbine blade. c- 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of Dr. Ir. Wessel W. Wits. © 2012 Published.
    view abstract10.1016/j.procir.2012.05.045
  • Modeling workpiece dynamics using sets of decoupled oscillator models
    Kersting, P. and Biermann, D.
    Machining Science and Technology 16 (2012)
    During the machining of thin-walled components, the dynamic behavior of the workpiece has a significant influence on the machining process and on the quality of the machined surfaces. In this article, a hybrid simulation concept for modeling regenerative workpiece vibrations is presented, which couples a geometric workpiece model with sets of decoupled harmonic oscillators to take the workpiece dynamics into account. © 2012 Copyright Taylor and Francis Group, LLC.
    view abstract10.1080/10910344.2012.731948
  • On the characteristics of high-performance internal peel grinding using electroplated cbn wheels
    Marschalkowski, K. and Biermann, D. and Weinert, K.
    Machining Science and Technology 16 (2012)
    The enhancement of material removal rates in hard machining is one major aspect of the applied cutting technologies; to increase the production rates. With respect to the required part quality, emphasis is put on the finishing process as a key element of the process chain. Especially internal finish operations constitute a challenging task because of the complex contact situation. This article presents a recent study on internal peel grinding, using the combined roughing-finishing procedure in combination with the excellent cutting performance of electroplated CBN wheels, to achieve highest removal rates with high surface finish. © 2012 Copyright Taylor and Francis Group, LLC.
    view abstract10.1080/10910344.2012.731950
  • Reduction of burr formation in drilling using cryogenic process cooling
    Biermann, D. and Hartmann, H.
    Procedia CIRP 3 (2012)
    Since deburring of components can amount to a considerable cost factor in machining, burr minimization strategies involve the potential of cost reduction. Due to that, they are of great interest for industrial applications. Beside tool geometry, material and cutting data, the applied cooling has an impact on burr formation. In this paper, a cryogenic process cooling with carbon dioxide snow jets is used to influence the burr formation in drilling in comparison to lubricated and dry machining. Burr height, surface roughness, diameter as well as roundness deviation were analyzed for drilling a quenched and tempered steel and an aluminum alloy. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.07.016
  • Simulation-based prediction of process forces for grinding free-formed surfaces on machining centers
    Rausch, S. and Odendahl, S. and Kersting, P. and Biermann, D. and Zabel, A.
    Procedia CIRP 4 (2012)
    During the grinding of hard materials using cylindrically and spherically shaped mounted points - like for the machining of complex forming tools with abrasive-wear-resistant coatings - the process force is an important factor influencing the accuracy of the machining outcome. A simulation-based prediction of these forces could be used to adapt the tool path and, thereby, to keep the grinding forces at a low level. In this paper, a simulation system based on the modeling of each grain of the grinding tool and the validation of this simulation model are presented. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.10.029
  • Thermal aspects in deep hole drilling of aluminium cast alloy using twist drills and MQL
    Biermann, D. and Iovkov, I. and Blum, H. and Rademacher, A. and Taebi, K. and Suttmeier, F.T. and Klein, N.
    Procedia CIRP 3 (2012)
    The deep hole drilling process with solid carbide twist drills is an efficient alternative to the classic single-lip deep hole drilling, due to the generally higher feed rates possible and the consequently higher productivity. Furthermore the minimum quantity lubrication (MQL) can be applied, in order to reduce the production costs and implement an environmentally friendly process. Because of the significantly reduced cooling performance when using MQL, a higher heat loading results for the tool and the workpiece. This paper presents the investigations of the temperature distribution in the workpiece and the heat balance of the deep hole drilling process. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.07.043
  • Using NC-path deformation for compensating tool deflections in micromilling of hardened steel
    Biermann, D. and Krebs, E. and Sacharow, A. and Kersting, P.
    Procedia CIRP 1 (2012)
    During the micromachining of hardened materials, the low stiffness of the milling tool results in an increased tool deflection which has a great influence on the shape and dimensional accuracy of the machined components. In order to compensate these deflections, an optimization method is presented in this paper. Based on measured form errors of the machined workpieces, the NC programs are optimized iteratively to reduce the shape deviations. To verify this method, experimental investigations were carried out by milling pockets in hardened steel. The results show a significant reduction of the tool deflection after the optimization. © 2012 The Authors.
    view abstract10.1016/j.procir.2012.04.022
  • A study on micro-machining technology for the machining of NiTi: Five-axis micro-milling and micro deep-hole drilling
    Biermann, D. and Kahleyss, F. and Krebs, E. and Upmeier, T.
    Journal of Materials Engineering and Performance 20 (2011)
    Micro-sized applications are gaining more and more relevance for NiTi-based shape memory alloys (SMA). Different types of micro-machining offer unique possibilities for the manufacturing of NiTi components. The advantage of machining is the low thermal influence on the workpiece. This is important, because the phase transformation temperatures of NiTi SMAs can be changed and the components may need extensive post manufacturing. The article offers a simulation-based approach to optimize five-axis micro-milling processes with respect to the special material properties of NiTi SMA. Especially, the influence of the various tool inclination angles is considered for introducing an intelligent tool inclination optimization algorithm. Furthermore, aspects of micro deep-hole drilling of SMAs are discussed. Tools with diameters as small as 0.5 mm are used. The possible length-to-diameter ratio reaches up to 50. This process offers new possibilities in the manufacturing of microstents. The study concentrates on the influence of the cutting speed, the feed and the tool design on the tool wear and the quality of the drilled holes. © ASM International.
    view abstract10.1007/s11665-010-9796-9
  • Achieving small structures in thin NiTi sheets for medical applications with water jet and micro machining: A comparison
    Frotscher, M. and Kahleyss, F. and Simon, T. and Biermann, D. and Eggeler, G.
    Journal of Materials Engineering and Performance 20 (2011)
    NiTi shape memory alloys (SMA) are used for a variety of applications including medical implants and tools as well as actuators, making use of their unique properties. However, due to the hardness and strength, in combination with the high elasticity of the material, the machining of components can be challenging. The most common machining techniques used today are laser cutting and electrical discharge machining (EDM). In this study, we report on the machining of small structures into binary NiTi sheets, applying alternative processing methods being well-established for other metallic materials. Our results indicate that water jet machining and micro milling can be used to machine delicate structures, even in very thin NiTi sheets. Further work is required to optimize the cut quality and the machining speed in order to increase the cost-effectiveness and to make both methods more competitive. © ASM International.
    view abstract10.1007/s11665-010-9789-8
  • Analysis of the influence of tool geometry on surface integrity in single-lip deep hole drilling with small diameters
    Biermann, D. and Heilmann, M. and Kirschnera, M.
    Procedia Engineering 19 (2011)
    The industrial relevance of bore holes with small diameters and high length-to-diameter ratios rises with the growing requirements on parts and the tendency of components for downsizing. Examples for components requiring deep holes with small diameters exist in the automotive industry; for the production of injectors for fuel injection as well as for medical and biomedical parts. Based on growing functional requirements, for example with the increase in injection pressure to improve the efficiency of the combustion process in diesel engines, the requirements on the surface integrity of bore holes also increase. To meet these requirements, an adaption of the deep hole drilling process is necessary. In this paper the influence of tool geometry, coating and cutting data on the bore hole quality and tool wear will be presented. © 2012 Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2011.11.073
  • Analysis of the laser drilling process for the combination with a single-lip deep hole drilling process with small diameters
    Biermann, D. and Heilmann, M.
    Physics Procedia 12 (2011)
    Due to the tendency of downsizing of components, also the industrial relevance of bore holes with small diameters and high length-to-diameter ratios rises with the growing requirements on parts. In these applications, the combination of laser pre-drilling and single-lip deep hole drilling can shorten the process chain in machining components with non-planar surfaces, or can reduce tool wear in machining case-hardened materials. In this research, the combination of these processes was realized and investigated for the very first time. © 2011 Published by Elsevier Ltd.
    view abstract10.1016/j.phpro.2011.03.138
  • Drilling CFRP thermosets using mounted points
    Biermann, D. and Feldhoff, M.
    Advanced Materials Research 325 (2011)
    Highly abrasive nature of carbon fibres and material-related problems like fibre or fibre bundle pullouts, matrix micro cracks and especially delamination of single or multiple laminate layers can be regarded as major problems when machining CFRP. This paper presents an approach using mounted points for drilling of fibre reinforced thermosets. The axial and thermal loads were recorded and quality criterions like the surface roughness, diameter deviation and the delamination at the tool exit side were quantified. Furthermore, an approach to improve the grinding process is presented. Results indicate that using mounted points are suitable for drilling operations in case of thermoset laminates. © (2011) Trans Tech Publications, Switzerland.
    view abstract10.4028/www.scientific.net/AMR.325.363
  • Experimental and computational investigation of machining processes for functionally graded materials
    Biermann, D. and Menzel, A. and Bartel, T. and Höhne, F. and Holtermann, R. and Ostwald, R. and Sieben, B. and Tiffe, M. and Zabel, A.
    Procedia Engineering 19 (2011)
    Experiments on dry face turning of functionally graded heat treatable steel are conducted. The workpieces have a hardened zone of approx. 60 HRC and a non-hardened zone of approx. 30 HRC. PCBN tools are used with different feeds, cutting speeds and depths of cut. Measurements of residual stresses in the surface layer reveal compressive stresses in the hardened zone and tensile stresses in the non-hardened zone. These experimental observations are compared with the results of representative simulations of the cutting process. A large-deformation thermo-elastoviscoplastic material model is used and the geometry of the cutting tool is precisely reflected by the finite element discretisation. To predict the overall response, an adaptive remeshing scheme and full thermo-mechanical coupling is accounted for. Moreover, measured residual stresses are incorporated as initial conditions within the simulation. © 2012 Published by Elsevier Ltd.
    view abstract10.1016/j.proeng.2011.11.074
  • Experimental investigations on drilling GFRP epoxy composite laminates using specialized and conventional uncoated cemented carbide drills
    Faraz, A. and Heymann, T. and Biermann, D.
    Materials and Manufacturing Processes 26 (2011)
    The growing demand of the fiber reinforced plastics (FRPs) in lightweight engineering has led to a need for assessing and quantifying the workpiece material defects, like hole exit delamination, during their drilling process. This article presents the experimental investigations on in-process drilling load profiles and a quantitative analysis of the induced hole exit delamination in drilling glass fiber reinforced plastic (GFRP) epoxy composite laminates, using various uncoated carbide drill bits (two specialized and a conventional one). The aim of studying and analyzing the in-process load profiles, in this work, is necessary in better comprehending the interaction between the tool and the workpiece material, with respect to the induced peak loads. It may further be helpful for determining and assessing the root cause of the induced delamination damage. Moreover, it is shown that the design and geometry of a particular drill bit also plays a vital role regarding its cutting loads and delamination results. The specialized tools were found to be much better than their conventional counterpart. Furthermore, subsequent drilling was conducted onto some predrilled pilot-holes using the same specialized drills, to test the chisel edge effect. The research emphasizes a need to pay attention to the quality and design of a drill bit (cutting edge corner). Copyright © 2011 Taylor & Francis Group, LLC.
    view abstract10.1080/10426911003636969
  • Flow drilling and thread forming of continuously reinforced aluminium extrusionsg
    Engbert, T. and Heymann, T. and Biermann, D. and Zabel, A.
    Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 225 (2011)
    Light-metal extrusions are widely used as frame-structure elements. Joining these profiles via screw coupling is a challenging task due to the small wall thickness of the extrusions and the missing accessibility within a frame structure. The combination of flow drilling and thread forming offers a possibility to cope with this task. These processing techniques allow the manufacture of stable threads in thin-walled structures with the profile accessible from one side only. Nowadays, aluminium profiles can be continuously reinforced through composite extrusion. Mechanical properties, like increased tensile strength compared with homogeneous profiles, make reinforced profiles preferable for applications such as safety-relevant components. However, the reinforcement can seriously affect machining processes as well as the machining results. Therefore, the flow-drilling operation, the thread-forming operation, and the process results have been analysed in detail with a new, difficult-to-machine material combination, namely steel-wire-reinforced aluminium extrusions. The crucial factor when machining lightweight extrusions are the forces acting perpendicular to the thin walls, so the influence of the reinforcement and the processing parameters on the feed force during flow drilling is presented. To examine the effect of the reinforcement on the thread-forming result and to quantify the benefit of flow drilling, the threads are stressed with a defined tensile load until failure.
    view abstract10.1243/2041297510394104
  • Hybrid manufacturing of deep holes with small diameters
    Biermann, D. and Heilmann, M.
    ASME 2011 International Manufacturing Science and Engineering Conference, MSEC 2011 1 (2011)
    Bore holes with a high length-to-diameter (l/D)-ratio and small diameters are needed in various industries. Examples are the downsizing of components for medical and biomedical products or for fuel injection in automotive industry due to the increase of injection pressure. For the production of deep holes with very small diameters an adapted process design is necessary, especially when the conditions at the begin of the deep hole drilling process are unfavorable. In these applications, a hybrid process consisting of a laser pre-drilling and a single-lip deep hole drilling can shorten the process chain in machining components with non-planar surfaces, or can reduce tool wear in machining case-hardened materials. In this research, the combination of laser and single-lip drilling processes for the machining of workpieces with non-planar surfaces was realized and investigated for the very first time. Copyright © 2010 by ASME.
    view abstract10.1115/MSEC2011-50226
  • Influence of controlled tool orientation on pattern formation and waviness in surface grinding
    Biermann, D. and Feldhoff, M.
    Production Engineering 5 (2011)
    The surface of ground components can exhibit quality impairments which are attributed to grinding wheel irregularities. A remaining grinding wheel imbalance or a non-uniform grinding wheel topography results in a radial run-out which strongly affects the generated surface. By measuring and adjusting the phase-shift of the grinding wheel orientation during consecutive grinding passes, the resulting workpiece surfaces can significantly be improved. Experimental investigations show a strong effect of the phase-shift on the waviness profile and the pattern formation, as the pattern wave length coincides with the tangential feed. Setting the phase-shift directly affects the engagement conditions like the contact stiffness, remarkably influencing the dynamic process behaviour. The amplitudes of the normal force at rotational frequency have a strong effect on the workpiece surface, which can be influenced by a variation of the phase-shift. Constancy of table oscillating period will further increase due to faster machine control hardware, making longer periods of constant phase-shifts more likely to occur. As this parameter is mostly uncontrolled, it can cause intermittent grinding errors. © 2010 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-010-0278-6
  • Intelligent process planning methods for the manufacturing of moulds
    Biermann, D. and Zabel, A. and Michelitsch, T. and Kersting, P.
    International Journal of Computer Applications in Technology 40 (2011)
    The layout of temperature control systems for moulds is decisive for the performance and stability of the production process. A design and optimisation approach for temperature control systems is introduced, coping with geometric constraints and complex thermal dependencies and allowing a significant reduction of manufacturing costs. Five-axis milling processes are increasingly used for the production of moulds in order to achieve high surface qualities and low manufacturing times. The CAM-programming required for the milling of free-formed surfaces in this field is complex and error-prone. An approach is shown, which automatically generates five-axis NC-paths from existing error-free three-axis paths. Copyright © 2011 Inderscience Enterprises Ltd.
    view abstract10.1504/IJCAT.2011.038551
  • Machining of a hollow shaft made of β-titanium Ti-10V-2Fe-3Al
    MacHai, C. and Biermann, D.
    Proceedings - 2011 IEEE International Symposium on Assembly and Manufacturing, ISAM 2011 (2011)
    In several fields of application it is important to apply components with a balanced combination of high strength, low density and a high chemical resistance. The aerospace sector uses titanium-based materials to manufacture lightweight parts of increased safety such as structural components, turbine disks and blades or landing gears. The latter are often made of -titanium alloys offering the highest strength-to-weight ratio. New applications of this emerging group of alloys can be developed if a hollow shaft of high strength is available, for example in the drive train of automobiles. The presented process sequence for manufacturing a hollow -titanium shaft consists of an incremental forming process followed by a longitudinal turning operation. The machinability of the -titanium alloy Ti-10V-2Fe-3Al is investigated at the undeformed raw material featuring two different conditions of heat treatment, and is compared with the machinability of the formed hollow shaft. Beside the cutting speed, the heat treatment of the material determines the development of tool wear and the occurring process forces. © 2011 IEEE.
    view abstract10.1109/ISAM.2011.5942364
  • Machining of β-titanium-alloy Ti-10V-2Fe-3Al under cryogenic conditions: Cooling with carbon dioxide snow
    MacHai, C. and Biermann, D.
    Journal of Materials Processing Technology 211 (2011)
    Titanium alloys are widely used in applications that demand a good combination of high strength, good corrosion resistance and low mass. Beta-Titanium alloys offer the highest specific strength among titaniumbased materials. The mechanical properties lead to challenges in machining operations such as high process temperatures, high specific mechanical loads and rapidly increasing tool wear. The high chemical reactivity of titanium leads to rapidly developing flank and notch wear limiting cutting speeds and tool life. Applying industrial gases instead of conventional cooling and lubrication fluids promises increased productivity. In this work, the effectiveness of carbon dioxide snow (CO2) as a coolant for turning Ti-10V-2Fe-3Al is analyzed. The carbon dioxide is provided in a pressurized gas bottle and is fed to the tool tip through holes in the tool holders clamping jaw. Compared to flood emulsion cooling the flank wear was uniform spreaded and tool life was increased by a factor of two even at higher cutting speeds. Tool-life-limiting notch wear and the burr formation at the workpiece have been suppressed. © 2011 Elsevier B.V. All rights reserved.
    view abstract10.1016/j.jmatprotec.2011.01.022
  • Manufacturing of dies from hardened tool steels by 3-axis micromilling
    Biermann, D. and Baschin, A. and Krebs, E. and Schlenker, J.
    Production Engineering 5 (2011)
    In this paper the results of an experimental investigation to analyze the machinability of a hardened, carbide-rich cold-work tool steel 1.2379 (approx.62 HRC) with coated micro end-milling cutters are discussed. Fundamental experiments were performed to determine a cutting-parameter set, which enables an economic manufacturing of dies by 3-axis micromilling with commercially available cemented-carbide tools. The evaluation of the applicability of different tool types is conducted by analyzing the process forces, the tool wear, the surface quality, the material removal rate, and the entire chip volume. Design of experiments was used to significantly reduce the number of experiments and to model the active and passive forces. Concerning the design of tools for the micromilling of such difficult-to-machine materials, it is shown that cemented-carbide tools with robust cutting edges are applicable for this kind of machining. Furthermore, test microstructures were manufactured with the intention of validating the determined cutting-parameter set in combination with the selected tool types. In addition, the dimension and shape accuracy of the microstructures are analyzed. © 2011 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-010-0293-7
  • Non-rigid isometric ICP: A practical registration method for the analysis and compensation of form errors in production engineering
    Sacharow, A. and Balzer, J. and Biermann, D. and Surmann, T.
    CAD Computer Aided Design 43 (2011)
    The unprecedented success of the iterative closest point (ICP) method for registration in geometry processing and related fields can be attributed to its efficiency, robustness, and wide spectrum of applications. Its use is however quite limited as soon as the objects to be registered arise from each other by a transformation significantly different from a Euclidean motion. We present a novel variant of ICP, tailored for the specific needs of production engineering, which registers a triangle mesh with a second surface model of arbitrary digital representation. Our method inherits most of ICP's practical advantages but is capable of detecting medium-strength bendings i.e. isometric deformations. Initially, the algorithm assigns to all vertices in the source their closest point on the target mesh and then iteratively establishes isometry, a process which, very similar to ICP, requires intermediate re-projections. A NURBS-based technique for applying the resulting deformation to arbitrary instances of the source geometry, other than the very mesh used for correspondence estimation, is described before we present numerical results on synthetic and real data to underline the viability of our approach in comparison with others. © 2011 Elsevier Ltd. All rights reserved.
    view abstract10.1016/j.cad.2011.07.007
  • Processing and damping properties of sputtered NiTi thin films for tools in machining processes
    Kahleyss, F. and De Miranda, R.L. and Surmann, T. and Zamponi, C. and MacHai, C. and Biermann, D. and Quandt, E.
    Journal of Materials Engineering and Performance 20 (2011)
    Nowadays, many manufacturing processes require the machining of complex forms with a high aspect ratio or cavities. Tools with a long overhang length are a common method to meet these requirements. Typical examples for this are boring bars for bore-turning and the milling with very long cutters. These tools tend to vibrate strongly due to their slender shape. The stress-induced transformation of austenite to martensite and the distinctive hysteresis loop allow the NiTi shape memory alloys (SMA) to absorb vibration energy. This article describes the innovative approach to dampen process vibrations by coating the tool shafts of cutting tools with long overhang with NiTi thin films. It explores how these thin films can be applied on polished tungsten carbide shafts and how their modal parameters are modified by these coatings. In a further step, this knowledge is used to calculate stability charts of corresponding machining processes. The study reported in this article identified the stabilizing effects of coatings with a thickness of 2-4 lm on milling processes. The minimum stability limit was increased by up to 200%. © ASM International.
    view abstract10.1007/s11665-011-9847-x
  • Subsequent drilling on pilot holes in woven carbon fibre reinforced plastic epoxy laminates: The effect of drill chisel edge on delamination
    Faraz, A. and Biermann, D.
    Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 225 (2011)
    Experimental results on thrust force and quantitative delamination are compared after drilling selected woven epoxy carbon fibre reinforced plastic (CFRP) laminates using two different drill bits. The results were acquired from two separate drilling modes: the normal drilling mode and the subsequent drilling conducted on some predrilled pilot holes. The use of pilot holes in drilling fibre reinforced plastics (FRPs) has been recommended by various researchers, following the basic concepts of drilling of metals and theoretical modelling. According to researchers, the drilling thrust force is directly correlated to the hole exit delamination; therefore, a pilot hole should minimize the hole exit delamination by nullifying the so-called chisel edge effect of a drill bit. A chisel edge, which is always regarded as the most inefficient part of a drill bit, is the biggest contributor to the thrust force. In this paper, despite the observed tremendous drops (as high as 92 per cent) recorded in the experimental thrust force magnitudes while conducting subsequent drilling on predrilled pilot holes, no improvement could be witnessed in the quantitative results on the induced hole entry and exit delamination. The main inference of this research is that the main cutting edges of a drill (along with their corners) do play a decisive role with regard to the hole exit delamination, instead of the role of the chisel edge alone. © 2011 Authors.
    view abstract10.1177/0954405411413335
  • The Correlation of Thermo-Mechanical Stresses on Cutting Tool Wear
    Biermann, D. and Felderhoff, J.F. and Heilmann, M.
    Friction, Wear and Wear Protection: International Symposium on Friction, Wear and Wear Protection 2008 Aachen, Germany (2011)
    view abstract10.1002/9783527628513.ch95
  • A general approach to simulating workpiece vibrations during five-axis milling of turbine blades
    Biermann, D. and Kersting, P. and Surmann, T.
    CIRP Annals - Manufacturing Technology 59 (2010)
    Workpiece vibrations have a significant influence on the machining process and on the quality of the resulting workpiece surface, particularly when milling thin-walled components. In this paper a simulation system, consisting of an FE model of the workpiece coupled with a geometric milling simulation for computing regenerative workpiece vibrations during the five-axis milling process, is presented. Additionally, a modeling method for visualizing the resulting surface is described. In order to validate the simulation model, turbine blades were machined and the experimental results were compared to the simulation results. © 2010 CIRP.
    view abstract10.1016/j.cirp.2010.03.057
  • A macroscopic approach towards the finite element simulation of tapping and thread milling of continuously reinforced extrusions
    Biermann, D. and Grüert, S. and Steiner, M.
    Production Engineering 4 (2010)
    The Finite Element Analysis (FEA) is a suitable tool for the process design and the determination of technical failure. Within this paper, the FEA is used for simulating and analyzing the thread milling process and the tapping process for reinforced lightweight extrusion profiles. Two different finite element models are developed to simulate both processes. An elastic material behavior is implemented in the simulation. For the tapping process, the computed stresses during the process as well as the geometrical displacements are considerably higher than the stresses computed for the thread milling operation. This is caused by the lower mechanical loads occurring in the thread milling process. The results can be used to identify areas of high stresses which may cause material failure. Moreover, both processes can be analyzed with respect to their influence on the workpiece. The simulation results are compared to experiments. © German Academic Society for Production Engineering (WGP) 2010.
    view abstract10.1007/s11740-010-0270-1
  • A measuring device for experimental modal analysis of thin-walled workpieces on five-axis milling machines
    Kersting, P. and Biermann, D. and Peuker, A.
    International Journal of Material Forming 3 (2010)
    During the milling process of flexible structures, such as thin-walled profiles manufactured for the aerospace industry, the dynamic behavior of the workpieces can become a key factor that limits the productivity of the machining process. Therefore, knowledge of the dynamic characteristics of the components prior to the milling process is important and provides the possibility to choose appropriate values for the process parameters. The experimental modal analysis is an adequate procedure to study the dynamic properties of components under vibrational excitation. In this process, the response of the structure is measured at defined points under controlled conditions when the structure is artificially excited by an input force. In case of thin-walled components, the response should be measured in a contactless way using laser systems to avoid the disturbance of the moving sensor mass. In order to design this process to be manageable, a device was designed connecting the laser system to the spindle of the milling machine. In this paper, the device, the experimental setup, and the software developed for programming corresponding NC paths are presented. The practicability of the system is also demonstrated analyzing the dynamic behavior of a turbine blade on a five-axis milling machine. © 2010 Springer-Verlag France.
    view abstract10.1007/s12289-010-0804-2
  • Analysis and simulation of size effects in micromilling
    Biermann, D. and Kahnis, P.
    Production Engineering 4 (2010)
    In this paper the influence of a downscaling of the tool diameter and of the machining parameters on the milling process is analyzed. Starting with an analysis of the cutting edge radius of the tools, the influence of the downscaling on the process is determined by analyzing the surface quality and the cutting forces. The simulation system NCChip, which has been developed at the ISF, is used to simulate the cutting forces when using small tool diameters. This simulation is also used to predict the cutting forces for more complex engagement conditions, like increasing radial immersion or milling of a slot pocket. Additionally, the effects of a downscaling on the tool deflection are analyzed, and strategies to reduce these effects are investigated. © German Academic Society for Production Engineering (WGP) 2009.
    view abstract10.1007/s11740-009-0201-1
  • Burr Minimization Strategies in Machining Operations
    Biermann, D. and Heilmann, M.
    Burrs - Analysis, Control and Removal: Proceedings of the Cirp International Conference on Burrs, 2009 (2010)
    Reducing burr formation in machining operations is of vital importance as they can decrease the functionality of components and can cause injuries. Nowadays, additional processes for deburring are often necessary. To avoid deburring, the modification of machining processes is a promising approach. Here, different parameters have a significant influence on burr formation. For example, the use of alternative machining processes or the reduction of the workpiece temperature near the edge of the workpiece shows high potential for burr reduction. This temperature reduction causes a change in material properties which decreases burr formation. In this paper, methods for burr minimization in various cutting processes are presented. Burr reduction strategies for turning, drilling and milling of different materials are presented.
    view abstract10.1007/978-3-642-00568-8_2
  • Development of a honing process for the combination machining of hardened axisymmetric parts
    Biermann, D. and Marschalkowski, K. and Paffrath, K.-U.
    Production Engineering 4 (2010)
    This paper presents a novel concept to enhance the conventional combination machining 'turning and grinding' by a long-stroke honing process for finishing bores of axisymetric parts. Honing is the best choice when the surface integrity of tribologically highly-stressed parts is of vital importance. The presented approach reduces the required overall machining time when compared with that of the conventional machining sequence on separate machine tools, and also enhances the production accuracy through a single clamping setup. The fundamental details like tool design, infeed strategies and possible process-chains of the developed approach for honing on a combination machining center are explained. Experimental results of two different process-chains are analyzed: Firstly, the 'turning-grinding-honing' (TGH-chain), where honing is conducted after the grinding process; and secondly, the 'turning-honing' (TH-chain), where honing is applied directly after the rough turning. The experiments showed promising results for the applied position-controlled infeed strategy of the developed long-stroke honing process regarding the production efficiency. © 2010 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-010-0223-8
  • Development of temperature sensor thin films to monitor turning processes
    Tillmann, W. and Vogli, E. and Herper, J. and Biermann, D. and Pantke, K.
    Journal of Materials Processing Technology 210 (2010)
    Increasing demands on the cutting process require a fundamental analysis concerning the design as well as the material selection for cutting insert and its wear protection. Apart from monitoring the wear and the cutting forces, the knowledge of the developed temperatures during cutting process is essential and necessary. In this work, an innovative technology was employed to measure in situ the temperature development during cutting process. The measurement was based on the Seebeck-effect. Coating adhesion was systematically analyzed and optimized by varying the pretreatment conditions. Furthermore, the design of masks was enhanced and finally turning experiments were carried out to scrutinize the efficiency of deposited temperature sensors in cutting tests. © 2010 Elsevier B.V. All rights reserved.
    view abstract10.1016/j.jmatprotec.2010.01.013
  • Direct free-form deformation of NC programs for surface reconstruction and form-error compensation
    Biermann, D. and Sacharow, A. and Surmann, T. and Wagner, T.
    Production Engineering 4 (2010)
    In this paper a new approach for manufacturing modified workpieces by milling is presented. In course of product development, several optimization iterations are often required, in which the shape of the workpiece is modified. Conventional method for manufacturing modified workpieces includes a time-consuming and error-prone step of reverse engineering, where the new CAD/CAM data is generated with respect to the measurement data of the manufactured workpiece. The new approach generates a continuous deformation function in order to approximate the discrete displacement vectors between the initial and the modified shapes, and applies this function on the original NC programs of the workpiece. Hence, it is possible to directly manufacture the modified shape. The process of reverse engineering can be eliminated so that manufacturing costs and the time from workpiece design to the production decrease significantly. © 2010 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-010-0260-3
  • Dynamic Disturbances in BTA Deep-Hole Drilling: Modelling Chatter and Spiralling as Regenerative Effects
    Raabe, N. and Enk, D. and Biermann, D. and Weihs, C.
    Advances in Data Analysis, Data Handling and Business Intelligence (2010)
    The BTA deep-hole drilling process is a process that very often is one of the final steps in the production of expensive workpieces. For example axial bores in turbines or compressor shafts are produced with this process. A serious problem in deep-hole drilling is the formation of dynamic disturbances that may be subdivided into the most common disturbance types chatter and spiralling. Chatter shows in self-excited rotational vibrations which lead to an increased tool-wear while spiralling is governed by bending vibrations and causes holes with several lobes. Since such lobes are a severe impairment of the bore hole the formation of spiralling has to be prevented. One common explanation for the occurrence of spiralling is the intersection of time varying bending eigenfrequencies with multiples of the tool's rotational frequency. Little is known about which specific eigenfrequencies are crucial. Furthermore an underlying assumption of this explanation is, that the resulting holes in cross-sectional view are appearing as a curve with constant width. This assumption implies that spiralling results from a parallel displacement of the drill head. We disprove this assumption and show a way how stability charts for the classification between stable and unstable processes can be computed by means of simulations. These simulations result from statistical-physical models which model the disturbances chatter and spiralling as regenerative effects.
    view abstract10.1007/978-3-642-01044-6_68
  • Empirical modeling of hard turning of AISI 6150 steel using design and analysis of computer experiments
    Sieben, B. and Wagner, T. and Biermann, D.
    Production Engineering 4 (2010)
    In the present paper an experimental study to investigate the turning of hardened AISI 6150 heat treatable steel using polycrystalline boron nitride (PCBN) tools is presented. Design and analysis of computer experiments (DACE) was used to generate a comprehensive empirical description of the process characteristics. More specific, the effects of the parameters cutting speed, feed and depth of cut on the objectives tool wear, tool life, tool life volume, surface finish and process forces were modeled. A total of 157 experiments was carried out with 15 different parameter-value sets to obtain the training data for modeling the progression of the objectives versus cutting path length and width of flank wear land. Pseudo-3D surface plots are generated to visualize the effects and interactions. Unexpected effects of depth of cut on tool life were found and the validity of conclusions about the effect of cutting speed on tool wear and tool life are discussed. Moreover, qualitative explanations for some of the observed effects are presented. © 2010 German Academic Society for Production Engineering (WGP).
    view abstract10.1007/s11740-010-0208-7
  • Finite element modeling and three-dimensional simulation of the turning process incorporating the material hardness
    Biermann, D. and Höhne, F. and Sieben, B. and Zabel, A.
    International Journal of Material Forming 3 (2010)
    Newly developed functionally graded workpieces made of AISI 6150 (51CrV4), pose great challenges to the machining process due to the combination of different material properties (e. g., hardness) within one workpiece. A material model including more information than experimentally identified stress-strain curves for different temperatures is necessary to model the process more realistically. Therefore, the Johnson-Cook material model has been implemented for three-dimensional turning simulations within the Finite Element software DEFORMTM 3D. This paper outlines the adopted method to modify the parameters of the Johnson-Cook material model for two-dimensional and three-dimensional FE-simulations in order to take material hardness into account. The primary objective was to improve passive and feed force computation by using this modeling approach, as it was observed that common material modeling showed large deviations of the feed force and passive force from the measured force components. The calculated feed force and passive force, as well as the cutting force, are validated experimentally. In conclusion it is shown that the application of the Johnson-Cook material model reveals more valid results for modeling the turning of workpieces with varying hardness values. © 2010 Springer-Verlag France.
    view abstract10.1007/s12289-010-0806-0
  • Grinding of arc-sprayed tungsten carbide coatings on machining centers - Process configuration and simulation
    Biermann, D. and Mohn, T. and Blum, H. and Kleemann, H.
    Key Engineering Materials 438 (2010)
    This paper describes the special demands placed on the grinding of arc-sprayed WC-Fe coatings on a conventional machining center. Basic process configuration, experimental results, measurement methods and an approach for a hybrid simulation system are presented. © (2010) Trans Tech Publications.
    view abstract10.4028/www.scientific.net/KEM.438.115
  • Improvement of workpiece quality in face milling of aluminum alloys
    Biermann, D. and Heilmann, M.
    Journal of Materials Processing Technology 210 (2010)
    The compliance with the quality requirements of components is essential for the functionality of the whole product. With respect to parts with face-milled faces, the surface quality and the shape of the workpiece edges are of great interest. Frequently, these faces take over the function of seal faces where high demands on the surface integrity and burr formation exist. To ensure the workpiece quality that is required, nowadays additional processes for deburring are often necessary. To avoid deburring, the modification of machining processes is a promising approach. In this study, the influence of process cooling on workpiece quality is investigated. Using this approach, two effects are expected. The cooling is used to minimize a reduction of flow stress generated from the process heat, which than leads to a lower formability. The second effect relates to the kinetic energy of the snow blast for deburring by deformation and breakage of the burrs. Using a process cooling with carbon dioxide, the surface quality is enhanced and the burr formation is minimized. © 2010 Elsevier B.V. All rights reserved.
    view abstract10.1016/j.jmatprotec.2010.07.010
  • Modelling of a thermomechanically coupled forming process based on functional outputs from a finite element analysis and from experimental measurements
    Wagner, T. and Bröcker, C. and Saba, N. and Biermann, D. and Matzenmiller, A. and Steinhoff, K.
    AStA Advances in Statistical Analysis 94 (2010)
    In this paper, measurements from experiments and results of a finite element analysis (FEA) are combined in order to compute accurate empirical models for the temperature distribution before a thermomechanically coupled forming process. To accomplish this, Design and Analysis of Computer Experiments (DACE) is used to separately compute models for the measurements and the functional output of the FEA. Based on a hierarchical approach, a combined model of the process is computed. In this combined modelling approach, the model for the FEA is corrected by taking into account the systematic deviations from the experimental measurements. The large number of observations based on the functional output hinders the direct computation of the DACE models due to the internal inversion of the correlation matrix. Thus, different techniques for identifying a relevant subset of the observations are proposed. The application of the resulting procedure is presented, and a statistical validation of the empirical models is performed. © 2010 Springer-Verlag.
    view abstract10.1007/s10182-010-0149-7
  • Modified DLC-coated guide pads for BTA deep hole drilling tools
    Biermann, D. and Kessler, N. and Upmeier, T. and Stucky, T.
    Key Engineering Materials 438 (2010)
    The BTA (Boring and Trepanning Association) deep hole drilling process is commonly used to machine boreholes with a large drilling depth-to-diameter ratio (l/D) and outstanding workpiece quality. The asymmetric tool design leads to a nonzero radial component of the cutting force and the passive force, which are conducted to the borehole wall by so-called guide pads. These guide pads smooth the borehole wall by a forming process and improve the surface quality. Processes, that machine materials with a high adhesion tendency, such as high alloy stainless steel, suffer from poor surface quality in the borehole and the adhesion from the workpiece material on the guide pads. In this paper modified Diamond-Like-Carbon (DLC) coated guide pads for BTA deep hole drilling tools are investigated. The scope of the experiments was the reduction of the adhesion by reducing the friction coefficient of the guide pads, as well as the improvement of the quality of the borehole wall. © (2010) Trans Tech Publications.
    view abstract10.4028/www.scientific.net/KEM.438.195
  • Sequential parameter optimization of an evolution strategy for the design of mold temperature control systems
    Biermann, D. and Joliet, R. and Michelitsch, T. and Wagner, T.
    2010 IEEE World Congress on Computational Intelligence, WCCI 2010 - 2010 IEEE Congress on Evolutionary Computation, CEC 2010 (2010)
    Sequential Parameter Optimization (SPO) is a popular model-assisted approach for tuning the parameters of metaheuristics, which is based on models from the Design and Analysis of Computer Experiments (DACE). Despite the indisputable success of SPO, some of the assumptions behind DACE, such as deterministic output and stationary covariance, do not hold for parameter optimization. Thus, an analysis of enhanced covariance kernels for the consideration of noise is performed. Furthermore, the effects of different sequential sampling strategies and an increasing number of replicates of each design on the quality of the models are discussed. To accomplish this, an Evolution Strategy (ES) is tuned on the real-world optimization problem of designing Mold Temperature Control Systems. Based on the results, recommendations for the ES parameters are provided, insights about the robustness of DACE with respect to the violations are made, and recommendations for appropriate combinations of sampling strategies and covariance kernels are derived. © 2010 IEEE.
    view abstract10.1109/CEC.2010.5586314
  • Transplantation of thermally sprayed wear-resistant coatings by high pressure die casting of light metals
    Bach, Fr.-W. and Möhwald, K. and Zhang, Y. and Kerber, K. and Erne, M. and Biermann, D. and Zabel, A. and Peuker, A.
    Materialwissenschaft und Werkstofftechnik 41 (2010)
    By manufacturing structured functional-surface coated composites using suitable materials, the properties of components? surfaces can be specifically matched to their requirements which the specified substrate material can not, or can only partially, fulfil. In conventional process chains, thermal spraying and structuring by milling are independent stages in the component?s final processing phase. Using the procedure introduced here, thermal spraying is to be directly integrated into the high pressure die casting process. In this way, a manufacturing procedure for coated castings with functionalized surfaces is realised which, as far as possible, eliminates the finishing operation of coated cast parts. In contrast to conventional coating processes, the coating-layer is not applied to the component but to the casting mould or to the corresponding inserts and is transferred to the component as a structured functional-surface during each cast. Transferring this type of coating from the tooling surface to the casting; which is also referred to as transplant coating, requires a narrow process-window with respect to the coating adhesion to both the tooling surface and the cast part. The coating adhesion at the tooling surface must be high enough such that the coating is not detached during either the coating or the mould filling processes, but also low enough to be completely detached from the tooling during mould stripping and be able to be removed together with the cast part. For this reason, the initial priority of the current investigations is to obtain a specific coating adhesion by adapting both the tooling surface, which is manufactured by milling, as well as the coating systems and the atmospheric plasma spray?s parameters for the most precise moulding of such plasma sprayed structures. Furthermore, investigations are introduced on forming composites from the cast material and the coating materials and results are presented of preliminary casting tests for transplanting thermally sprayed coatings onto aluminium and magnesium alloys during high pressure die casting. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    view abstract10.1002/mawe.201000625
  • coatings

  • cutting

  • deep hole drilling

  • finite element method

  • friction

  • manufacturing

  • modelling and simulation

  • tribology

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