518 Int. J. Productivity and Quality Management, Vol. 29, No. 4, 2020 Copyright © 2020 Inderscience Enterprises Ltd. Performance study of eco-friendly dielectric in EDM of AISI 2507 super duplex steel using Taguchi-fuzzy TOPSIS approach V. Srinivas Viswanth*, R. Ramanujam and G. Rajyalakshmi School of Mechanical Engineering, VIT University, Vellore, 632014, India Email: srinivas.viswanthv2012@vit.ac.in Email: ramanujam.r@vit.ac.in Email: rajalakshmi@vit.ac.in *Corresponding author Abstract: In the present study, the application of Pongamia natural ester as a renewable green dielectric (GD) applied in the electric discharge machining (EDM) of AISI 2507 super duplex steel. This investigation aims to study the effect of Pongamia green dielectric in the EDM process. The major process variables such as pulse-on time (T ON ), pulse-off time (T OFF ), peak current (I P ), voltage (v) and inter-electrode gap (IEG) on performance measures like material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR). The Taguchi’s orthogonal array (OA) L 27 has been selected for this experimentation. The choice of optimal input parameter settings that are attained by multi-response optimisation of performance measures using Taguchi-fuzzy-TOPSIS technique is T ON = 500 µs, T OFF = 30 µs, I P = 15 A, v = 40 V and IEG = 180 µm. The optimal settings have increased the productivity aspects by the four decision makers (DM) order priorities. The optimised results, shown the improvement in MRR with the minimised EWR and SR. The optimal settings of the process for improved machining responses were identified by Taguchi’s response graph and analysis of variance (ANOVA). The recast layer and micrographs were examined utilising scanning electron microscopy (SEM). Keywords: electric discharge machining; EDM; green dielectric; electrode wear rate; EWR; surface roughness; SR; Taguchi; productivity; fuzzy-TOPSIS; material removal rate; MRR. Reference to this paper should be made as follows: Viswanth, V.S., Ramanujam, R. and Rajyalakshmi, G. (2020) ‘Performance study of eco-friendly dielectric in EDM of AISI 2507 super duplex steel using Taguchi-fuzzy TOPSIS approach’, Int. J. Productivity and Quality Management, Vol. 29, No. 4, pp.518–541. Biographical notes: V. Srinivas Viswanth is a full time Research Scholar at the School of Mechanical Engineering (SMEC), Vellore Institute of Technology (VIT) University, Vellore. He received his BTech and MTech from the Sri Venkateswara University, Tirupathi and Visveswaraya National Institute of Technology (VNIT), Nagpur in 2006 and 2009, respectively. His research work is in the field of optimisation techniques and unconventional machining processes.