Effect of cooling and lubrication conditions on cutting performance and surface integrity of Inconel 718 superalloy in end face milling

Abstract

Inconel 718 nickel-based superalloy has superior thermal and mechanical properties. Nevertheless, it is a hard-to-machine material, and the heat generated by processing is excessive. Reasonable cooling and lubrication (CL) methods have essential effects on its cutting performance and surface integrity. In this study, Dry cutting (DC), flood cutting (FC), cryogenic cutting (CC), and cryogenic minimum quantity lubrication cutting (CMQLC), are used to cutting Inconel 718 under the same parameters. Cutting forces, temperature, tool wear, chip, Ra, microstructure, and residual stress (RS) are measured. It is concluded that the combination of CL is beneficial for processing. The average temperature obtained by CMQLC is 55.47% lower than that of DC. And the workpiece obtained by CMQLC is measured compared with FC, the area of tool chipping is reduced by 25%, and the surface Ra is decreased by 32.05%, the lowest among the four methods. As for RS, although TRS increased by 7.9%, the MCRS and influence depth of the subsurface increased by 3.9% and 10.2% respectively. Furthermore, the machining condition with a high mechanical thermal ratio can obtain a more favorable RS state. Generally speaking, the CMQLC shows the advantages of mild environmental pollution, preferred cutting performance, and superior workpiece surface integrity.