Prediction of surface roughness in CNC turning operation using taguchi design of experiments

Abstract

This paper outlines the Taguchi optimisation methodology, which is applied to optimise cutting parameters in turning when machining hardened steel AISI 4140 with carbide insert tool under semifinishing and finishing conditions of high speed cutting. All the experimental work has been conducted on CNC lathe at Kaizen Machine Tools, Faridabad, Haryana. The experiments carried out by using L-27 (313) orthogonalarray. The turning parameters evaluated are cutting speed, feed rate and depth of cut. An orthogonal array, signal-to-noise (S/N) ratio and Pareto analysis of variance (ANOVA) are employed to analyse the effect of these turning parameters on surface roughness. Main effects of process parameters on the quality characteristics have been analysed and the results show that the optimum parameter setting for surface roughness is obtained at a cutting speed of 200 m/min, feed rate 0.1 mm/rev and depth of cut 1.5 mm and the optimum parameter setting for force required is obtained at a cutting speed of 200 m/min, feed rate 0.1 mm/rev and depth of cut 1 mm. Confirmation tests with the optimal levels of cutting parameters are carried out in order to illustrate the effectiveness of Taguchi optimisation method. Using Taguchi method for design of experiment (DOE), other significant effects, such as, the interaction among turning parameters are also investigated.