Hybrid optimization approach on electrical discharge machining process for hybrid Al-Al2O3/B4C composites

In the present investigation, influences of process parameters such as pulse current, pulse on time, gap voltage, and sample compositions on the machining of hybrid Al-Al₂O₃/ B₄C composites through wire electrical discharge machining (WEDM) are carried out. The parameters were optimized to minimize both material removal rate (MRR) and surface roughness (SR) through Taguchi and Grey relational analysis. The hybrid
Al-Al₂O₃/ B₄C MMCs containing the micro-particles of Al₂O₃ (purity 99 % and 100-325 mesh size) and B₄C (purity 99% and 400 mesh size) were prepared by stir casting with varying proportions (i.e. 100/0, 75/25, 50/50, 25/75 and 0/100) of Al₂O₃ and B₄C as a reinforcements. The morphology of the machined samples was also examined through SEM and found the presence of micro-ridges, micro craters, micro-cracks, black patches, debris, and micro-voids. The experimental results revealed the optimal grouping of process parameters as sample composition of B75A25 (75% B₄C +25% Al₂O₃), pulse on time of 32 μs, pulse current of 2 A, and gap voltage of 40 V.