Multi-objective optimisation of EDM process using hybrid Taguchi-based methodologies for Ti-6Al-4V alloy

Advanced hard-to-machine materials are difficult to manufacture. This work explores the application of electrical discharge machining (EDM) of Ti-6Al-4V alloy for different pulse parameters. Machining performance is evaluated by material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR). For the experiment, orthogonal array have been found using Taguchi methodology. The optimum parametric settings obtained by grey relational analysis (GRA)-based Taguchi method which was compared with hybrid grey relational-principal component analysis (PCA)-based Taguchi. It was found that GRA-based PCA optimisation methodology results more feasible parametric setting which has also been confirmed by the validation experiments. The rectangular pulse current shape and its duration have found to be significant. The optimum value of process variables were pulse duration of 5µs, duty factor of 11%, peak current of 30 A and gap voltage of 9 V to achieve maximum MRR and lower TWR with better surface finish. [Received 10 April 2015; Revised 16 May 2016; Accepted 17 May 2016]