Multi-objective optimization of drilling EDM process parameters of LM13 Al alloy–10ZrB2–5TiC hybrid composite using RSM

Abstract

In this study, a newly engineered stir-cast LM13 aluminium alloy-based hybrid composite (5 wt% of TiC and 10 wt% of ZrB2) is used as workpiece and its machinability investigation is carried out using EDM (electric discharge machining) drilling route with copper electrode. During experimentation, the process variables, namely current (I), pulse on-time (Ton) and pulse off-time (Toff), are varied and the output performance characteristics, viz. material removal rate (MRR), electrode wear rate (EWR) and dimensional accuracy, i.e. overcut (OC), are measured. The series of experiments (20 runs) are formulated through the adoption of response surface methodology (RSM)-based full-factorial central composite design. To recognize the correlation between the process variables and performance characteristics, a mathematical model is developed for each response. Subsequently, adequacy of the proposed models is verified using analysis of variance (ANOVA). Moreover, ANOVA is employed to identify the significantly influencing process parameters over the performance characteristics. From the analysis of results, it is inferred that the current has the most dominant effect on MRR and EWR, whereas OC is highly influenced by Ton. Composite desirability function approach of RSM is utilized to find the optimum set of process parameters in order to satisfy the desired multi-performance characteristics (such as maximizing MRR, minimizing EWR and OC) for obtaining effective holes on hybrid LM13–10ZrB2–5TiC composite. Finally, optimized results are validated with the experimental results to determine the competence of adopted desirability approach.