Effects of cutting parameters on chip morphology and tool wear in high-speed face milling of hardened steel

High-speed face milling of hardened steel was conducted to investigate the effects of cutting parameters on chip morphology and tool wear. It was found that the tool-chip contact length decreased substantially as the cutting speed increased over 2000 m/min. The adiabatic shear theory is more suitable for describing the formation of individual saw-tooth obtained in the present study. When the cutting speed was relatively low, relatively long tool life can be obtained at large radial depth of cut. On the contrary, when the cutting speed was relatively high, smaller radial depth of cut was beneficial for the acquisition of longer tool life. When the cutting speed was relatively low, due to relatively high mechanical load at relatively small radial depth of cut, large flaked region arose on the tool rake face and the main wear mechanisms of the tool flank face was fracture. However, when the radial depth of cut was relatively large, because of the relatively low mechanical load, there was no flaking on the tool rake face. There existed thermal crack perpendicular to the cutting edge due to the relatively high cutting temperature. When the cutting speed was relatively high, due to the drastically reduced tool-chip contact length, there was very small area of coating delamination near the cutting edge (at relatively small radial depth of cut) or no wear near the cutting edge (at relatively large radial depth of cut).