The machinability of Inconel 718

Inconel 718, a high strength, thermal resistant Nickel-based alloy, is mainly used in the aircraft industries. Due to the extreme toughness and work hardening characteristic of the alloy, the problem of machining Inconel 718 is one of ever-increasing magnitude. This paper discusses the effect of cutting conditions on the machinability of Inconel 718. Flank wear of the inserts, workpiece surface roughness and cutting forces will act as the performance indicators for tool life while machining is carried out using a CNC lathe. Two types of coated cemented carbide inserts, grades EH20Z-UP (TiN coated by physical vapour deposition) and AC25 (TiN coated by chemical vapour deposition), were used. Various combinations of side cuffing edge angles (SCEAs), cutting speeds and feedrates were tested at a constant depth of cut. Cutting results indicate that SCEA, together with cutting speed and feedrate, do play a significant role in determining the tool life of an insert when machining Inconel 718.