Influences of cutting fluid conditions and cutting parameters on surface integrity of Inconel 718 under high-pressure jet-assisted machining (HPJAM)

Cutting fluids are widely used in machining processes for cooling and lubricating the tool and workpiece interface to enhance machinability. However, the generation of machined surface under cutting fluid conditions is more complex than that under dry cutting conditions. In this study, orthogonal turning of the difficult-to-machine Inconel 718 alloy is conducted under dry and high-pressure jet-assisted machining, respectively. The machining parameters and coolant conditions are investigated to optimise the surface integrity. Machining forces, microhardness, profile, and areal surface topography are analysed. Results show that a higher cutting speed of 140m/min and a coolant pressure of 150 to 200bar are the optimums to produce a satisfactory machined surface. High-pressure coolant in cutting processes can lower the formation of surface deformities, improve surface integrity, and increase productivity. At a higher cutting speed and optimum coolant pressure, cutting forces are decreased, and the surface hardness as well as depth of the machining-affected zone is depleted.