Wear characteristics and wear control method of PVD-coated carbide tool in turning Inconel 718

As nickel-based alloy Inconel 718 has poor thermal conductivity and serious work hardening, it is classified as a difficult-to-cut material. The tool wear is very serious. In this paper, PVD-coated carbide tools were employed to cut Inconel 718. Firstly, tool wear morphology and tool wear mechanism were studied. The results show that tool wear characteristic changed with cutting speeds. There was an optimum cutting speed at which oxides serving as boundary lubrication layer formed. These oxides can reduce the friction coefficient of the tool-chip contact surface and inhibit tool wear. Secondly, according to the wear mechanism analysis, tool flank wear model was established in the light of wear delamination theory. The optimum cutting temperature was proposed, and it was calculated using the established model. At the optimum cutting temperature, tool wear can reach the minimum value. At last, verification experiments for the optimum cutting temperature were carried out. For a pair of tool-workpiece, the minimal tool wear can be obtained by optimizing cutting conditions so as to make the cutting temperature reach the optimum value. This provides a good method for tool wear control. It also provides a theoretical basis and effective means for a reasonable choice of cutting parameters.