Tool Wear of WC-Co-Based Cemented Carbide in External Thread Turning of Super Heat-resistant Alloy Inconel 718 with High-Pressure Coolant Supply

Super heat-resistant alloy Inconel 718, which is a component of gas turbines and aircraft engines, is difficult to cut. Many researches have been conducted on tool wear in high nickel alloy cutting. Conventionally, when cutting a work material with poor thermal conductivity, it is effective to decrease the cutting speed, prolong the tool life, and use a tool material with high thermal conductivity. High-pressure coolant cutting is effective for reducing the cutting temperature, and many studies on high-pressure coolant cutting have been conducted. In this study, super heat-resistant alloy Inconel 718 was screw thread turned with high-pressure coolant supply, and the tool wear was experimentally investigated. The cutting materials used was an un-coated ISO K10 cemented carbide. The "VNl," "VC" and "VNr" were measured, where the "VNl," "VC" and "VNr" were the maximum values of flank wear widths on the left side of the flank face, on the corner side of the flank face and on the right side of the flank face, respectively. The following results were obtained: (1) In the case of a cutting speed of 1.00 m/s, fracture of cutting part was observed in the conventional coolant supply. It was possible to suppress the tool wear with pressure coolant supply. (2) In the case of a cutting speed of 1.00 m/s, comparing the "VNr," "VC " and "VNl," "VC" was the smallest at any coolant pressure, and the "VC" decreased with the increase of the coolant pressure "P." Furthermore, the "VNr" and "VNl" decreased with the increase of the coolant pressure. (3) In the case of a cutting speed of 1.50 m/s, as compared among the "VNr," "VC" and "VNl," "VC" was the smallest at any coolant pressure, and the "VC" decreased with the increase of the coolant pressure.