Performance of PVD coated carbide inserts when machining a nimonic (C-263) alloy at high speed conditions

Physicals Vapor Deposition (PVD) coated carbide inserts were used to machine a nickel-base, C-263, superalloy under severe cutting conditions. Test results show that the TiN/TiCN/TiN coated, inserts with positive, honed and chamfered edges (Tool A) outperformed similar tools with double positive edges and no edge protection (Tool B) in terms of tool life as well as lower flank wear rate when machining under roughing conditions. The double positive edges of Tool B inserts are more susceptible to chipping action due to reduced tool-chip and tool-workpiece contact lengths/areas and associated increase in applied stresses at the cutting edge during machining. Increase in cutting conditions and variation of the cutting edge geometry did not increase the surface roughness value due to the elastic recovery of the C-263 alloy. Prolonged machining causes appreciable increase in the feed force due to the rapid work hardening of the nimonic alloy as well as the formation of hard burrs during machining.