Influence of tool flank wear on performance of finish hard machined surfaces in rolling contact

This study investigates the influence of tool flank wear on the performance of finish hard machined surfaces in rolling contact. The residual stress and micro-hardness distribution below the machined surface and the surface roughness of the machined surface were measured to investigate the rolling contact fatigue performance. The fatigue life predictions and the fatigue test results indicate that the change in fatigue life by tool flank wear is highly variable depending on the machining conditions. It is conceivable that tool flank wear reduces the fatigue life, since less compressive residual stresses and more softened layer typically decrease the rolling contact fatigue life. However, tool flank wear does not reduce the fatigue life for some specimens. It is noted that tool flank wear can even increase the fatigue life by lower stress at crack initiation depth or lower driving force for crack propagation although tool flank wear induces less compressive residual stresses and more softened layer.