Fabrication of Macro-Arrayed Structure using Reverse EDM: A Multi-objective Optimization

In the past few years, applications like surface texturing and fin-like structures for heat dissipation demands development of arrayed structures. At micro-scale, micro reverse electro-discharge machining (M-REDM) proved its ability to fabricate such arrayed structure. Very few attempts have been made at the macro level. In this research, an attempt has been made to check the feasibility of fabrication of macro-rod arrayed structure of Ø 5 mm × 4 mm using reverse EDM (REDM) on AISI D2 steel. Pulse ON time (Ton), pulse current (Ip) and gap voltage (Vg) were selected as process parameters while material removal rate (MRR), tool wear rate (TWR), surface roughness and taper angle were chosen as response variables. The experimental investigation has been planned using Taguchi L9 orthogonal array and process parameter optimization carried out using various multi-attribute decision making (MADM) methods i.e. simple additive weighting (SAW), weighted product method (WPM) and grey relational analysis (GRA) to get the best suitable alternative among them. From the results obtained during experimentation, it can be seen that the MRR and surface roughness was mostly affected by Ip whereas TWR was mostly affected by Ton having the highest contribution among all process parameters. Taper angle in the range of 3° to 5° was observed. Optimized set of process parameters obtained using WPM and GRA method is in accordance with each other whereas SAW method ranked it second best alternative which is as follows: Ton = 155 μs; Ip = 9 A and Vg = 40 V.