Experimental Analysis for Multi Criteria Optimization for Drilling Process for En 31 Material

Abstract

The paper deals with optimization of surface finish and hole diameter accuracy in the dry drilling process by using Taguchi method with input parameters as speed, drill depth, feed and type of tool. The experiment was conducted on CNC drilling machine using HSS twist drills for EN31 steel.The parameters of hole quality are analyzed 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 analyze 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 effects on the hole diameter accuracy; cutting speed and drill depth have significant effects on the surface finish. Confirmation tests with the optimal levels of machining parameters were carried out in order to illustrate the effectiveness of the Taguchi optimization method. The validity of Taguchi’s approach to process optimization is well established.