Cutting forces and surface roughness in wet machining of Inconel alloy 738 with coated carbide tool

Inconel 738 is a precipitation-strengthened nickel-based superalloy, which is widely used in hot sections of gas turbine engines due to its excellent high-temperature strength and superior hot corrosion resistance. In this article, effects of machining parameters (cutting speed, feed rate and depth of cut) on machining forces (thrust force, feed force and cutting force) and surface roughness were investigated in machining of Inconel 738 using coated carbide tool and cutting fluid. Results were analyzed with response surface methodology and analysis of variance, and a second-order regression mathematical model was proposed for cutting forces and surface roughness. The results showed that all three machining parameters had significant effect on cutting forces. The most effective parameters were depth of cut, cutting speed and feed rate ordered by magnitude of effectiveness. Regarding surface roughness, feed rate was the most effective parameter. Comparison between effect of cutting speed and depth of cut on surface roughness indicated that cutting speed had more considerable effect. Finally, the ranges for best cutting conditions were proposed for serial industrial production.