Optimization of wire electrical discharge machining process parameters of LM24 al alloy - TiB2 - fly ash reinforced hybrid composites

To optimize the Wire Electrical Discharge Machining (WEDM) process for machining a hybrid composite (7.5wt% TiB2 and 2.5wt% fly ash), Response Surface Methodology (RSM) and desirability function were applied for multi-objective optimization of WEDM parameters, aiming to maximize Material Removal Rate (MRR) and minimize Surface Roughness (Ra). The results were validated through confirmation tests. The stir-cast hybrid composite’s increased hardness and strength were attributed to its fine, round, and evenly distributed microstructures. SEM and EDS studies confirmed the even distribution and strong bonding of fly ash and TiB2 within the LM24 alloy matrix. Pulse duration was identified as the most significant factor. The study successfully optimized the two conflicting goals, MRR and Ra, simultaneously. The best set of parameters identified by the desirability function was: pulse duration (P) = 110.36 µs, inter-pulse time (I) = 40.0001 µs, cutting speed (C) = 1.19995 mm/min, and servo control voltage (S) = 54.9995 volts. This combination yielded a desirability score of 0.942, indicating a good compromise between material removal rate and surface quality. Confirmation tests showed minimal associated errors in MRR (2.57%) and Ra (0.31%). SEM analysis of the machined surface revealed uniformly distributed discharge craters, further confirming the success of the optimization method. This study also compared the Desirability function and Grey Relational Analysis (GRA) for optimizing WEDM of the hybrid composite. The comparison revealed distinct optimal parameter sets from each method, reflecting an inherent trade-off: the Desirability Function favored a higher MRR, while GRA prioritized a lower Ra. These insights are crucial for guiding parameter selection based on application-specific needs, whether for maximizing productivity or achieving superior surface quality.