Investigation into some surface characteristics of electrical discharge machined SKD-11 using powder-suspension dielectric oil

This project investigates the property effect of additives on surface quality of EDMed SKD-11. The additives with significantly different thermophysical properties, including aluminum (Al), chromium (Cr), copper (Cu), and silicon carbide (SiC) powders are studied. Experimental results show that the particle size of additives in the dielectric oil affects the surface quality of EDMed work. While the smallest particles (70–80 nm) generates the best surface finish of the machined work, the greater the particle size the less the improvement in the surface roughness. However, particle size has opposite effect on the recast layer, as the smallest particles generated the thickest recast layer of the EDMed surface, and the greater the particle size the thinner the recast layer. Among the additives, Al powder produces the best surface finish and the thinnest recast layer in the machined work, whereas the process without foreign particles and with copper powder, generates the worst surface characteristics.