Tool wear and surface modifications in metal machining

Jannica Heinrichs, Uppsala University, Sweden

Reducing wear to prolong tool life is a key challenge in metal machining. To facilitate that, the active wear mechanisms need to be understood, and in our research group we are working to contribute to this increased understanding. Our methodology comprises tribological testing combined with careful surface analysis, to identify the wear mechanisms and observe any changes to the surfaces. The metal machining process will not only result in tool material removal but also in tool surface modifications, vastly important for the wear process. After machining, the tool surfaces are studied in detail, using high resolution scanning electron microscopy, elemental analysis, and surface profiling as our key methods. The machining tests are complemented by sliding tests, where the chip formation process is omitted in favour of successive detailed analysis of the tool surface, enabling studies of the wear initiation and observations of minute wear. Further, the tool wear is strongly dependent on the work material, influencing wear mechanisms, surface modifications and acceptable cutting parameters. This talk will be focused on machining of titanium alloys, known to be difficult to machine materials causing rapid wear of the tools, but also case hardening and carbon steels will be touched upon.