3 rd International Conference on Production and Industrial Engineering CPIE-2013 756 Abstract - The present work is proposed to solve multi-response optimisation problem in Electric discharge machining (EDM) using Grey-fuzzy logic method. The responses are Material Removal Rate (MRR), Tool Wear Rate (TWR) and Surface Roughness (SR) of EDM. The work piece material was AISI P20 tool steel and a cylindrical copper electrode with side impulse flushing was used as a tool. The discharge current, pulse on time, work time, lift time, and Inter Electrode Gap (IEG) were the control parameters of EDM. Taguchi method using L 27 orthogonal array was used to design the experiment and the effect of the factors on the responses were studied. The optimal parameter setting for maximum MRR and Minimum TWR and SR was obtained by Grey-fuzzy logic method. Keywords - Electric Discharge machine (EDM), Grey-fuzzy logic, AISI P20 tool steel, Multiple Responses Optimisation I. INTRODUCTION EDM is an electro-thermal non-traditional machining Process, where electrical energy is used to generate electrical spark and material removal mainly occurs due to thermal energy of the spark. EDM is mainly used to machine difficult-to-machine materials and high strength temperature resistant alloys [1]. The Taguchi method has been used to optimise single quality characteristic and produced better quality products at a low cost [2]. However, this technique cannot be used for optimisation of multiple quality characteristics [3]. Lin and Lin [4] presented the optimisation of EDM process with multiple process responses using Grey-fuzzy logic method. Optimisation of multiple responses like machining precision and accuracy using fuzzy logic techniques in high speed EDM presented by Tzeng and Chen [5]. Pandey and Dubey [6] have applied the fuzzy logic optimisation of multiple quality characteristics in laser cutting of Duralumin sheet. II. EXPERIMENT METHOD II-A. Design of Experiment- The experiments were conducted on Electronica Electraplus PS 50ZNC Die Sinking Machine. Experimental setup is shown in Fig.1. Commercial grade EDM oil (specific gravity = 0.763, freezing point= 94˚C) was used as dielectric fluid with impulse flushing pressure of 0.3 kgf/cm 2 . The machining parameter and their level are presented in Table 1. The five machining parameters, each at three levels, were selected based on Orthogonal Array (OA), resulting in Twenty-seven experiments that are shown in Table 2. To attain more accurate results, every combination runs of experiments was machined for 60 min and then MRR was calculated by weight loss method. Central line average (Ra) value of the machined surface was measure of the surface roughness, it usually expressed in microns. Portable style type profilometer, Talysurf (Model: Taylor Hobson, Surtronic 3+) was used for measurement. Fig.1 Experimental setup TABLE 1 MACHINING PARAMETER AND THEIR LEVELS Control Parameter Parameter Levels Unit 1 2 3 Discharge current (Ip) 2 5 8 A Pulse on Time (Ton) 100 300 500 μs Lift Time (Tup) 0.0 0.7 1.4 s Work time (Tw) 0.2 0.6 1.0 s Inter Electrode Gap (IEG) 90 170 250 μm Multiple Response Optimisation of EDM Process Using Grey-Fuzzy Logic Technique Shailesh Dewangan 1 , C.K.Biswas 2 and Ritanjali Sethy 3 1-3 Department of Mechanical Engineering, National Institute of Technology, Rourkela, India (shaileshdewangan123@gmail.com)