Application of the Taguchi technique for the optimization of surface roughness and tool life during the milling of Hastelloy C22

In this study, the effects of machining parameters on surface roughness (Ra) and tool life (Tl) were investigated in the milling of Hastelloy C22 alloy with TiAlN-coated carbide inserts. A number of milling experiments were conducted using the L-27 (3(3)) Taguchi orthogonal array on a CNC milling machine under different cutting conditions (dry, compressed air and wet). The cutting condition, cutting speed and feed rate were determined as the essential machining parameters. Analysis of variance (ANOVA) and signal-to-noise (S/N) ratio were employed to evaluate the effects of the machining parameters on Ra and Tl, and prediction models were created using quadratic regression analyses. The results revealed that the feed rate and cutting condition were the most influential factors on surface roughness and flank wear. The maximum tool life was achieved under wet cutting condition using a cutting speed of 30 x min(-1) and a feed rate of 0.08 mm x rev(-1), while the minimum surface roughness value was obtained under wet cutting condition using a cutting speed of 50 m x min(-1) and the same feed rate. Using the optimum cutting parameters for Tl (30 m x min(-1), 0.08 mm x rev(-1)), increases of 234 % and 67 % in tool life were observed under wet and compressed air cutting conditions, respectively, compared to the dry cutting condition.