Investigation of Cutting Conditions and Cutting Edge Preparations for Enhanced Compressive Subsurface Residual Stress in the Hard Turning of Bearing Steel

Residual stresses in the machined surface and the subsurface are affected by cutting tool, workpiece, tool/workpiece interface, and cutting parameters, such as feed rate, depth of cut and cutting speed. The prediction of residual stress profile in the machined surface is difficult due to the lack of proper material model to depict the material behavior and the complex interaction among the dominant factors. In this paper, the effects of workpiece hardness, tool geometry as well as cutting conditions on the residual stress distribution in the hard machined surface are investigated using a newly proposed hardness-based flow stress model employed in an elastic-viscoplastic FEM formulation. Special attention is paid to the effect of cutting edge preparation on the beneficial as well as the penetration depth of the residual stress in the machined surface. Simulation using different cutting edge preparations, namely sharp edge, small hone, large hone, chamfer and different combinations of hone plus chamfer, are conducted to obtain residual stress profile on the machined surface. Numerical results show an optimal combination of large hone edge + chamfer and aggressive feed rate help to increase compressive residual stress in both axial and circumferential directions.