Experimental investigation and machining analysis of Mg/TiC composites during EDM

Electrical discharge machining (EDM) is one of the prominent non-conventional machining processes used to machine metal matrix composites. Mg/TiC composites are found in many industrial applications and conventional machining of the same is highly challenging. This paper aims to study the machinability analysis of Mg/TiC composites using EDM with pulse-on time ( T on ), pulse-off time ( T off ) and input current ( I ) as the process variables with the material removal rate (MRR) and surface roughness (SR) as the performance measures. Stir cast Mg-alloy reinforced with TiC (0, 5, 10, 15 and 20) by weight was used as the workpiece. The EDM experiments were conducted as per L 25 orthogonal array (OA) and the results were analyzed to study the effect of the process variables on MRR and SR. The parametric study showed that SR increases linearly with T on and is attributed to larger craters produced at a higher pulse energy. MRR was also observed to grows with the rise in T on as more material melts due to high-intensity pulses. As per the ANOVA results, T on was found to be the most influential process variable affecting SR and MRR with a 79% and 34% contribution, respectively. Surface morphology investigations using SEM micrographs revealed the presence of globules and sphere-shaped metal deposits and were found responsible for increased SR.