Effect of micro-electrical discharge drilling parameters on machining responses during machining of Al/(SiC/ZrO₂/NiTi)-MMC

The use of metal matrix composites is increasing gradually in numerous industrial applications. As a result of increased demand, accurate and precise machining of the composites in microdomains become important. Micro-electrical discharge drilling can be effectively applied for machining micro-holes in hybrid composites. The effect of micro-drilling process parameters such as pulse-on-time, pulse-off-time, peak current, tool rotation and electrode polarity on the material removal rate (MRR), radial overcut (RO) and tool wear rate (TWR) has been identified. Results reveal that the MRR, RO and TWR increase as the peak current, pulse-on-time and tool rotation increase. A copper tool with positive polarity provided better results when compared to the other combinations. Although MRR was reduced by 11.22%, RO and TWR were improved by 14.51% and 59.52%, respectively, in a grey relational analysis-based optimal parametric setting. Scanning electrode microscopic (SEM) images of the machined surface demonstrate that the machined holes have high circularity, less surface damage and negligible recast layer at the optimal setting.