Tool Life and Workpiece Surface Integrity Evaluations when Machining Ti-6Al-4V with PVD Coated Tools

摘要

Tool life data are presented for two grades of physical vapour deposition (PVD) TiN and TiN/TiCN/TiN-coated tools when machining titanium Ti-6Al-4V (IMI 318) alloy. The paper also details some aspects of workpieces surface integrity at various cutting conditions, including analysis of surface finish, microhardness and microstructure variations. The results show that when machining Ti-6Al-4V with the PVD coated tools tool life was significantly improved compared with the straight tungsten carbide (C-2) tool. Under roughing conditions involving high feed rates, the surface finish generated during machining can be lower than the ideal value due to the plastic flow of surface material. The hardness values in the surface layer were usually higher than the base material due to the hardening of the surface layer as a result of the high pressure and high cutting temperatures generated during machining. The lower hardness values of the extreme surface layer were however recorded due to overaging caused by high local heating.