Machinability analysis and optimisation of EDM in AA6082/3 wt% BN/1 wt% MoS₂ hybrid composites using entropy method weights integrated with complex proportional assessment (COPRAS) method

An investigation was made on composites containing AA6082 as matrix and boron nitride/molybdenum disulphide (BN/MoS₂) as reinforcement, which was a composite materials hybrid at 3 wt% of BN and 1% MoS₂ and fabricated by stir casting methodology. Using electrical discharge machining (EDM) equipment, machinability studies were undertaken to achieve an optimal condition on process parameters. Taguchi (L27 orthogonal array)-based design of experiments was employed to examine the influence of process parameters like pulse on time (T_on), peak current (IP), and gap voltage (V) on material removal rate (MRR), circularity (CIRC), electrode wear rate (EWR), and cylindricity (CYLD). Multi-criteria decision-making (MCDM) methodology was employed for the process parameters while machining AA6082/3 wt% BN/1% MoS₂ hybrid composites. An entropy-based objective weights method was integrated with the complex proportional assessment (COPRAS) approach to assess the most excellent optimal level of process parameters. The entropy (W_j) weights were 0.1285, 0.1002, 0.5707, and 0.2005 for MRR, EWR, CIRC, and CYLD. Optimal conditions are obtained from the COPRAS method of relative significance score, and quantitative utility assessment score in the nineteenth experiment having the 15 A, 50 μs, and 30 V with the relative significance score of 0.0735 and a higher quantitative utility score of 100% being achieved. Using an SEM, the machined surface is analysed for the micro-structural examination. At higher peak current (IP), micro-voids and craters with poor surface finish were located.