Experimental study and analysis of micro holes machining in EDM of SS 304

Electrical discharge machining (EDM) has become a widely accepted non-conventional material removal process for machining features which are difficult-to-machine but conductive materials. In this paper, material removal rate (MRR), tool wear rate (TWR) and overcut (OC) are investigated using effect of three controllable input variables namely pulse on time, discharge current, and voltage. Experiments were conducted on stainless steel grade 304 (SS 304) using tubular brass electrode based on the L9 orthogonal array with Taguchi method has been studied. Analysis of variance (ANOVA) was performed and signal-to-noise (S/N) ratio were determined to know the level of importance of the machining parameters. According to S/N ratio the optimal parametric combination for higher MRR, lesser TWR and OC are suggested. Based on ANOVA, pulse on time is the most significant parameter for MRR, TWR and OC. The optimised process parameters simultaneously leading to a higher MRR, lesser TWR and OC are then verified through a confirmation experiment. The validation experiments show an improved MRR of 31.54%, TWR of 5.97% and OC of 2% when the Taguchi method is used.