Study on the influence of green plant-based dielectric fluids and process feasibility in electrical discharge-assisted milling of Nickel-Based Alloy 718

Electrical Discharge Assisted Milling (EDAM) proves to be a highly effective and viable process for machining nickel-based alloy 718. The use of conventional hydrocarbon oil (EDM oil) as the dielectric fluid for machining nickel-based alloy 718 generates hazardous by-products, posing serious risks to laboratory personnel and the environment. To mitigate the environmental and safety hazards associated with conventional EDM oil, this study employs green plant-based dielectric fluids (Canola oil, Peanut oil) as alternative fluid in the electrical discharge assisted milling process. Through comparative experiments on the designed system, key performance indicators such as surface microhardness, surface chemical composition, surface morphology integrity, electrode wear rate, and cutting force after workpiece machining were evaluated to comprehensively investigate the feasibility of green plant-based dielectric fluids in this hybrid machining technology. Experimental results indicate that green plant-based dielectric fluids is an effective alternative to EDM oil. During machining in EDM oil, Canola oil, and Peanut oil, the cutting force amplitudes were 323.4 N, 302.6 N, and 281.5 N, respectively. Compared to EDM oil, Canola oil and Peanut oil reduced cutting forces by 6.4% and 12.9%, respectively. Surface roughness first decreases and then increases with increasing capacitance, reaching its optimal value at 1 µF. The roughness under Peanut oil is reduced by 26.5% and 21.1% compared to EDM oil and Canola oil, respectively. At a capacitance parameter of 1 µF, optimal machined surface quality is achieved, with Peanut oil as the dielectric fluid yielding the best surface integrity of the workpiece.