Process Parameter Optimization for EDM Machined Stainless Steel

Electro Discharge Machining (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, dies, sections of complex geometry and intricate shapes. The work piece material selected for this study is AISI 304L Stainless steel. In the present work the effect and percentage contribution of various machining parameters on output parameters is studied using Taguchi’s method and ANOVA analysis. A hybrid Taguchi based grey relational analysis is proposed for multi objective optimization of performance variables i.e. high material removal rate, low tool wear rate, better surface finish with lower dimensional tolerance. Further a regression analysis can be used for finding the model equations for various performance parameters. The input parameters considered in this study are dielectric flow rate, discharge current, Pulse on time (Ton) and Pulse off time (TOff). The tool material used is copper. Analysis of variance is used to study the significance of process variables on Material Removal Rate (MRR), Tool Wear Rate (TWR), Surface Roughness (Ra), Dimensional Tolerance (DT). The analysis using Taguchi method reveals that discharge current significantly affects MRR, Dimensional Tolerance and Ra whereas TWR is mostly affected by flow rate of the dielectric used. A comparison of the hybrid approach and Taguchi analysis is presented in this study. The confirmation test supports the result of the proposed hybrid Grey-Taguchi analysis.