Surface characteristics of in-situ Al-2Mg/20 Al3Fe composite in wire-EDM: experiments, modeling and optimizations by MORSM and metaheuristic approaches.

The wire-electrical discharge machining (wire-EDM) is increasingly recommended for the machining of complex-shaped components with high surface finish and geometrical accuracy, specifically for difficult-to-machine advanced materials like Al-matrix composite (Al-MCs). The related research is primarily restricted to ex-situ Al-MCs, although in-situ ordered intermetallics reinforced Al-MCs are receiving growing attention due to their superior comprehensive mechanical properties. The present work deals with an Al-2Mg/20 vol.% in-situ Al₃Fe composite manufactured by the reactive stir-casting method and focuses on its machining by wire-EDM via experimental and computational approaches. Experiments have been conducted following the response surface method (RSM) considering four process variables, namely, pulse-on time (T_ON), servo voltage (S_V), peak current (I_P) and wire feed rate (W_FR). The integrity of the machined surfaces has been characterized by evaluating the change in surface chemistry (CSC) and surface roughness (SR), while the material removal rate (MRR) has been determined as the machining performance index. Analysis of variance (ANOVA) and RSM-based mathematical models reveal that T_ON is the most influencing parameter, and it raises MRR and SR but reduces CSC considerably. The optimization of machining conditions has been performed by metaheuristic approaches, namely, Teaching and Learning-based optimization (TLBO) and Artificial Bee Colony (ABC) apart from multi-objective RSM (MORSM) based on the trade-off analysis. The performances of TLBO and ABC techniques are found to be identical and provide much greater MRR at the cost of diminished surface integrity, i.e., higher SR and CSC, when compared with the MORSM technique. The robustness of the developed models has been validated by confirmatory experiments with a calculated overall error of ≤ ± 8%. Finally, the surface integrity aspects are reaffirmed and correlated with input variables through detailed characterizations of the machining surfaces by FESEM-EDS. [ABSTRACT FROM AUTHOR]