Comparative Evaluation of Coated Carbide and CBN Inserts Performance in Dry Hard-Turning of AISI 4140 Steel Using Taguchi-Based Grey Relation Analysis

Dry hard-turning is a vital manufacturing method for machining hardened steel due to its low cost, high efficiency, and green environmental protection. This study aims analyze the effect of various parameters on cutting forces surface roughness by employing RSM ANOVA. In addition, multi-objective optimization (Grey Relation Analysis: GRA) performed determine optimum parameters. tests were carried out AISI 4140 (50 HRC) using coated carbide CBN inserts with different nose radii. The results show that force components are greatly affected depth speed both inserts. As level rise, also increase. However, feed rate was main factor in roughness. A lead good quality. According results, exhibited better performance compared terms minimum lowest radial (Fx = 55.59 N), tangential (Fy 15.09 (Fz 30.49 best quality (Ra 0.28 µm, Rz 1.8 µm) obtained tool. Finally, based GRA, (V 120 m/min, f 0.04 mm/rev, 0.06 mm, r 0.8 mm) have been chosen as minimize all responses simultaneously