Surface characteristics and recast layer thickness analysis of µed machined Inconel 718 alloy with biodiesels

Abstract

ABSTRACT µED-milling is a modern machining process for manufacturing precise microstructures on a wide variety of conductive materials without considering their mechanical properties. Using mineral oils as a dielectric fluid in µEDM causes a hazardous environment for the operator. This study attempts to identify the substitute for hydrocarbon oil during milling of Inconel 718 at various order of discharge energy. Neem and Sunflower biodiesels are chosen as dielectric fluids and a comparison was made in terms of response measures of EDM oil. Top (higher) order discharge energy offered a maximum MRR with EDM oil, Neem and Sunflower biodiesels. However, the EDM oil yielded a higher MRR than biodiesels due to its higher current conductivity and lower viscosity. The fine craters are achieved when lower-order discharge energy is used due to tiny sparks generated at machining gap. Neem biodiesel follows more closely with EDM oil than Sunflower biodiesel for all considered response measures. The contact angle of the machined surface with biodiesels is smaller than EDM oil attributed to the presense of broader craters in the surface. The recast layer thickness is increased by 92% and 44% with and Neem biodiesel than EDM oil.