Optimisation of cutting parameter for surface finish and hole accuracy in drilling of EN31: a Taguchi approach

Abstract

The study deals with optimisation of surface finish and hole diameter accuracy in the dry drilling process by applying Taguchi method with input parameters as speed, drill depth, feed and type of tool. The experiments were conducted on CNC drilling machine using HSS twist drills for EN31 steel. The parameters of hole quality were analysed under varying cutting speeds (30, 40, and 50 m/min), feed rates (0.2, 0.3, and 0.4 mm/rev), depths of drilling (15 and 20 mm), and different drilling tools (uncoated, TiN- and TiAlN) with a 118° point angle. Taguchi's experimental design method was used for settings of the drilling parameters. Orthogonal arrays of Taguchi, signal-to-noise (S/N) ratio, analysis of variance (ANOVA) and regression analyses were employed to find the optimal levels and to analyse the effect of the drilling parameters on surface finish and hole diameter accuracy. The outcome of this research revealed drill depth, feed rate and cutting speed have significant influence on the hole diameter accuracy; while cutting speed and drill depth have significant effects on the surface finish.