Analysis of material removal rate and recast layer in micro-EDM of non-conductive zirconia

Abstract

Inconsistency in material removal rate (MRR) and minimizing recast layer are critical issues in non-conductive ceramic machined using micro-EDM. Thus, this research presents the analysis of MRR and recast layer of zirconium oxide (ZrO2) due to micro-EDM using EDM-3 dielectric fluid and tungsten tool electrode. The investigation was performed using multi-process micro machine tools. The two main parts of this research are process development and the analysis of MRR and recast layer. For process development, assisting electrode (AE), polarity, flushing, feed rate, gap voltage, and rotational speed were the control parameters. The machined parts were observed using scanning electron microscope. The better machinability of ZrO2 was found to be with copper adhesive as AE, positive polarity of workpiece, feed rate 3 µm/s, and workpiece submerged in dielectric fluid with one way circulation. The best conditions in process development were used as the fixed parameters. Rotational speed and gap voltage were the control parameters for the analysis of MRR and recast layer. The results of MRR were obtained by measuring the mass of material removed over machining time. The recast layer hardness was measured using micro-Vickers hardness tester. The MRR and hardness data were analyzed and empirical models were developed using design expert software. The optimum parameters for maximum MRR found to be 375 rpm rotational speed and 80 V gap voltage. The optimum value for minimum recast layer hardness was 874.8 Hv with rotational speed of 378 rpm and gap voltage of 110 V