Wear of Coated Carbide Tools When Machining Nickel (Inconel 718) and Titanium Base (Ti-6A1-4V) Alloys

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Abstract
Nickel base, Inconel 718, and titanium base, IMI 318 (Ti-6A1-4V) alloys were machined with single (TiN) and multiple (TiN/TiCN/TiN) PVD coated carbide inserts at high cutting conditions in order to evaluate their performance and also to analyze their failure modes. The machining results show that coating material(s), tool geometry, machining parameters as well as material properties can singly or jointly affect tool performance and failure modes. Flank wear was the dominant failure mode at cutting speeds up to 42 m/min for the Inconel 718 alloy and up to 100 m/min for the IMI 318 alloy when machining at feed rates up to 0.25 mm/rev and depth of cut up to 2.00 mm. Excessive chipping/flaking off of tool particles and premature edge fracture also contributed to tool rejection, particularly when machining with the multi-coated inserts due to their sharp edges and instability of the machining system at higher speed conditions. The multi-layer coated tools generally produced lower flank wear rates, thus the best overall performance in terms of tool life, due to the higher resistance of the TiN/TiCN/TiN coatings to flank wear relative to the single TiN coating.