Effects of cutter path orientations on milling force, temperature, and surface integrity when ball end milling of TC17 alloy

To explore the effects of cutter path orientations on milling force, temperature, and surface integrity, end ball milling experiments of TC17 titanium alloy were accomplished derived from different cutter path orientations. The experiment results of milling force and temperature were obtained. Combining with the thermo-mechanical coupling, this paper analyzes the impact of the cutter path orientations on the surface roughness, surface topography, in-depth residual stress, microhardness distributions, and microstructure. The results indicate that the maximum milling force is 224.24 N and the temperature is 672°C under vertical downward milling path, while horizontal downward orientation provides the lowest cutting force of 81.12 N and temperature of 493°C. The surface topography of the four cutter path orientations is basin-like shape, and the minimum surface roughness of 1.128 µm is achieved under vertical upward mode. Moreover, the maximum compressive residual stress of −491.8 MPa and the maximum residual stress layer depth of 45 µm are acquired under vertical downward milling. The maximum microhardness can arrive at 390 HV_0.025 under the vertical path. Additionally, the transformation of the material microstructure remains elongated, bent, and fractured. The maximum plastic deformation layer depth is 44 µm under vertical downward milling path.