A Comparative Study for Machining of Ti-6Al-4V Alloy for Multi-Criteria Response

Nowadays, it has become very difficult for the manufacturer to satisfy all its customers with satisfactory products, as they have different demands considering the responses. However, hard to-machine materials are difficult to manufacture. This study explores the application of electro-discharge machining (EDM) of Ti-6Al-4V alloy with pulse duration (Ton), duty factor (f), peak current (Ip) and gap voltage (Vg) as the control parameters using pure copper electrode. Machining effects are evaluated by performance characteristics including material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) by considering the multi-criteria preference of the customers that vary with the preference of responses. For the experiment, proper orthogonal arrays are found out using Taguchi methodology. The optimum parametric settings were obtained by utility-concept-based Taguchi method which were compared with desirability-approach-based Taguchi. It was found that utility-concept-based Taguchi optimization methodology results in more feasible parametric setting which has also been confirmed by the validation experiments. The optimum values of process variables obtained were pulse duration of 30 mu s, duty factor of 9%, peak current of 10 A and gap voltage of 6 V to achieve maximum MRR and lower TWR with better surface finish to satisfy multi-user criteria.