Multi-objective optimization of electrical discharge drilling (EDD) process using PCA based grey relational analysis

Abstract

Low material removal rate (MRR) and formation of recast layer are major limitations of EDM which restrict large scale application of EDM in advanced manufacturing industries such as aerospace, defence, automobile, medical etc. Electrical Discharge Drilling (EDD) is a proficient machining process for machining of electrically conductive hard and tough materials. It is a combination of EDM and conventional drilling however in EDD process, tool and workpiece are not in mechanical contact as in case of conventional drilling process. The material is removed by melting and evaporation and at the same time tool rotation assists the process by improved flushing of debris particles from machining zone. In present work, holes of 2 mm diameter are machined in Ti-6Al-4V using EDD process. The experiments were performed on conventional EDM machine with a detachable in-house developed experimental setup for tool rotation. The experiments are designed using Taguchi’s L27 OA. Further, optimization of EDD process is performed using PCA based GRA method. The optimum values of process parameters for EDD of Ti-6Al-4V is obtained as IP = 21 Amp, TON = 90 µs, TOFF = 15 µs and tool rotation = 600 rpm. It is found that EDD at optimum parameters have resulted in about 30.64% increased MRR along with 16.57% greater TWR as compared to mean MRR and mean TWR at 21 Amp pulse current.