Parametric optimization of electro discharge machining for A356/TiB ₂ composite using neem oil dielectric: Machining performance and surface morphology analysis

A356 is a lightweight and high-strength aluminum alloy with excellent corrosion resistance, widely used in aerospace, automotive, and marine applications. However, machining of titanium diboride (TiB2)-reinforced A356 aluminum alloy using unconventional machining methods remains challenging due to the high thermal conductivity and low electrical conductivity, affecting machining efficiency and surface integrity. This study investigates electrical discharge machining (EDM) of A356-10TiB2 composite fabricated via stir casting, using neem oil dielectric fluid. The composite exhibited a hardness of 78.33 BHN. The EDM process was optimized using response surface methodology (RSM) to minimize surface roughness (SR) and maximize material removal rate (MRR) by varying supplied current (SC), pulse on time (Ton), and pulse off time (Toff). The correlation coefficients for MRR and SR were 99.07% and 99.91%, respectively. MRR and SR initially increased with SC, Ton, and Toff but decreased at higher levels. Higher SC and Ton increased ionization temperature, enhancing MRR, while lower values caused cracks and globules. Optimal parameters (SC = 10 A, Ton = 62 µs, Toff = 7 µs) yielded a maximum MRR of 0.211 g/min and minimum SR of 4.34 µm. The optimization error was 1.9% (MRR) and 3.97% (SR), with desirability score of 0.9865 confirming the reliability of the models.