Influence of tool path strategies on fatigue performance of high-speed ball-end-milled AISI H13 steel

This paper presents the findings of experimental investigations into the effects of tool path strategies on fatigue life of high-speed ball-end-milled AISI H13 steel. Milling operations were conducted under three different tool path strategies with four levels of feed per tooth 0.1–0.4 mm/z. Fatigue life of machined samples was tested by three-point bending fatigue tests. Results show that the fatigue performance is susceptible to tool path strategies. Different tool path strategies bring the difference in microscopic stress concentration induced by the orientational surface topography and the effective residual stress defined as the residual stress component along the applied tensile stress direction. These two aspects can alter the real maximum tensile stress suffered by the milled surface and then influence the fatigue performance. Moreover, optimization methods for the tool path selection are put forward based on the findings that the effective residual stress has more significant influence on fatigue performance than the microscopic stress concentration and the more compressive the residual stress is, the longer the fatigue life will be. This study indicates that the fatigue performance for a ball-end-milled surface can be improved from the tool path control point of view.