Green manufacturing: a comparative study of renewable dielectrics in the EDM process

Electrical discharge machining (EDM) is a nontraditional processing technology that can be used to process materials with a high melting point, high strength, high hardness and low brittleness. Kerosene, as a common dielectric, produces aerosol and toxic gas at high temperatures, which seriously affects the health of operators and air quality. In this study, edible vegetable oils such as sunflower oil, rapeseed oil and peanut oil were used as dielectric to improve the sustainability of EDM. The Taguchi method was used to design experiments, and the effects of vegetable oils with different viscosities on machinability during EDM were discussed from the perspective of mechanism. The machinability was evaluated with the material removal rate (MRR), energy efficiency per unit volume (EEV) and surface roughness (Ra). In addition, the debris diameters of different vegetable oils after processing were studied by using a super depth-of-field optical microscope. The results showed that the MRR of rapeseed oil was 28.9% higher than that of sunflower oil and 25% higher than that of peanut oil. In terms of the MRR, Ra and EEV, rapeseed oil also had obvious advantages because of its high viscosity. In addition, because of the high viscosity of rapeseed oil, the distribution proportion of large fragments was obviously larger than that of the other two oils. The proportion of debris larger than 35 mu m in rapeseed oil was 8.21% and that of sunflower oil was only 2.79%. Therefore, vegetable oils can be used instead of a kerosene dielectric to improve the sustainability of EDM and to realize green manufacturing.