Study of machining performance in EDM through response surface methodology

Abstract

Electric discharge machining (EDM) is thermal erosion advanced machining process which is capable of machining very hard conductive materials that cannot be machined by any other conventional machining processes. However, process parameters used in EDM have a wide range and for achieving efficient machining optimum selection of these parameters plays an important role. In the present study, discharge current (I), pulse on and pulse off time were taken as process variables in machining AISI 202 stainless steel using a copper alloy tool. This study aims to optimize electrode wear rate, material removal rate, as well as surface roughness of workpiece using response surface methodology (RSM) approach. The results obtained after experimental procedure were analyzed by analysis of variance (ANOVA) technique. Regression equation for the EWR, MRR, and Ra was also generated. This study also focuses on surface changes and crystalline changes that occur after EDM process by using different characterization techniques. Atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques have been used for studying the changes on materials after machining process. Based on the experiment, it was found that discharge current and pulse on time significantly affect the machining performance. The optimized electrode wear rate and material removal rate obtained were having values 0.000155 mg/min and 0.048175 mg/min, respectively. This study can be helpful for selecting optimum process parameters in machining of 202 stainless steel to achieve efficient machining.