Engineering

Poster

Influence of manufacturing chains on mechanical properties of friction drilled internal threads in aluminium alloy 6060

Anke Schmiedt, Institute for Design and Materials Testing (IKW), Department of Materials Test Engineering (WPT)/ TU Dortmund University, Dortmund, Germany
Philipp Wittke, Institute for Design and Materials Testing (IKW), Department of Materials Test Engineering (WPT)/ TU Dortmund University, Dortmund, Germany
Frank Walther, Institute for Design and Materials Testing (IKW), Department of Materials Test Engineering (WPT)/ TU Dortmund University, Dortmund, Germany
Y. Liu, Institute of Machining Technology (ISF)/ TU Dortmund University, Dortmund, Germany
Dirk Biermann, Institute of Machining Technology (ISF)/ TU Dortmund University, Dortmund, Germany

Aluminium alloys are used for enhancement of dynamic range, resource optimization and emission reduction in many fields of traffic engineering, whereby aluminium components are manufactured by means of welded, adhesive and screw joints. Friction drilling, as a 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 best and cut threads worst mechanical properties which were correlated to the production-related profile qualities and changes in microstructure. Multiple step tests prove that the fatigue limit of aluminum internal threads, validated in constant amplitude tests, can be reliably estimated by means of plastic strain.

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