Experimental investigation of MRR, surface roughness and overcut of AISI 304 stainless steel in EDM

Abstract

EDM has become an important and cost-effective method of machining extremely tough and brittle electrically conductive materials. It is widely used in the process of making moulds and dies and sections of complex geometry and intricate shapes. The workpiece material selected in this experiment is AISI 304 Stainless steel taking into account its wide usage in industrial applications. In today’s world 304 stainless steel contributes to almost half of the world’s production and consumption for industrial purposes. The input variable parameters are current, pulse on time and duty cycle. Taguchi method is applied to create an L27 orthogonal array of input variables using the Design of Experiments (DOE). The effect of the variable parameters mentioned above upon machining characteristics such as Material Removal Rate (MRR), Surface Roughness (SR) and Overcut (OC) is studied and investigated. The tool material is copper.
The results obtained showed that current was the most significant parameter followed by pulse on time and the least significant was the duty cycle for the entire three responses namely Material removal rate, Surface roughness and overcut. With the increase in current and duty cycle MRR increased but for pulse on time it increased only up to 100 µs and then started to decrease. SR increased significantly with the increase in current; for pulse on time it increased up to 100 µs and after that there was no significant increase; and in case of duty cycle SR increased up to 70% and then started to decrease. OC increased with the increase in current and pulse on time but in different fashion and in case of duty cycle, OC increased up to 70% and then started decreasing.