Analysis of discharge behavior, performance, and surface integrity in EDM of Inconel X-750 using different dielectric fluids for sustainable machining

Balancing productivity, surface integrity, and sustainability in EDM of Inconel X-750 remains a major challenge. The study evaluates how deionized water, an environmentally friendly dielectric, performs relative to conventional hydrocarbon oil, under controlled variations of pulse interval (Toff), pulse duration (Ton), and discharge current (Ip). Key responses, including surface roughness (SR), material removal rate (MRR), tool wear rate (TWR), surface morphology, topography, and elemental composition, were systematically analyzed. Hydrocarbon oil achieved significantly higher MRR and lower TWR, whereas deionized water produced smoother surfaces and thinner recast layers, exhibiting trends comparable to hydrocarbon oil and similar underlying material removal mechanisms. Surface and elemental analyses showed that dielectric properties and discharge energy govern surface integrity. With increasing Ip, hydrocarbon oil showed a sharp rise in MRR from 5.672 to 31.377 mm3/min, accompanied by SR increase from 2.778 to 6.226 µm, indicating higher productivity with reduced surface quality. In contrast, deionized water exhibited only a marginal MRR increase from 0.456 to 1.213 mm3/min while maintaining lower SR, increasing from 1.896 to 3.454 µm, highlighting its advantage in surface quality. The findings highlight the potential of deionized water for improving surface quality and sustainability during the machining Inconel X-750.