Multiscale FE-Studies of Contact Stresses of Dry and Lubricated Shot Peened Workpiece Surfaces

In production engineering cold forging processes are of great importance due to the high material utilization and the associated energy and resource efficiency. In order to perform cold forging processes successfully, liquid and solid lubricants are used, which are often questionable due to ecological, economic, and legislative reasons. For these reasons, dry metal forming exhibits an increased research potential. The absence of lubricants in dry metal forming contributes significantly to the waste reduction in manufacturing processes and to the goal of a lubricant-free factory. However, the abdication of lubricants goes along with the requirement that the dry tribological system has to withstand the increased tribological loads. In this contribution an empirical approach to meet the challenges in dry metal forming is proposed. Shot peened surface structures on workpieces are numerically investigated in order to identify friction and, thus, tool-load reducing surfaces compared with non-structured workpieces. In future work, this approach will be synthesized with a (Cr,Al)N PVD-tool-coating with self-lubricating disulfides to achieve a lubricant free cold forging