Study on the Effect of Cutting Parameters on Surface Quality and Cutting Force in Turning SKD11 Alloy Steel on CNC Lathe

Abstract

SKD11 steel is a high-alloy tool steel, widely used in die and mold manufacturing due to its superior hardness and wear resistance. However, machining SKD11 steel after heat treatment (hard turning) presents many challenges because of the high cutting forces and elevated cutting temperatures. This paper presents an experimental study to evaluate the effects of cutting parameters, including cutting speed v_c, feed rate f_z, and depth of cut a_p, on surface roughness (R_a) and spindle load (Load SPL) during CNC turning using Sumitomo carbide inserts. Using the Taguchi experimental design method with an L_9 orthogonal array, the analysis of variance (ANOVA) results shows that the feed rate f_z is the most dominant factor affecting surface roughness, with a contribution of 99.60%. Meanwhile, the depth of cut a_p has the greatest influence on spindle load, with a contribution of 62.76%. The study successfully developed second-order regression equations with high reliability (R^2>96%). The optimal parameter set was determined as v_c=130 m/min, f_z=0.12 mm/rev, and a_p=1.0 mm, enabling the achievement of a surface quality comparable to fine grinding (R_a=0.642 μm) while still ensuring safe machine loading.