Effect of graphene dispersed coconut biodiesel on the Micro ED milling characteristics of Inconel 718 alloy

Abstract

Abstract Micro Electrical discharge milling is a familiar micromachining process for machining of complex microstructures using a cylindrical tool. In this research work, the influence of process parameters namely capacitance, voltage, threshold on response indicators during machining of Inconel 718 with coconut biodiesel and graphene nano powder dispersed coconut biodiesel is investigated in detail. Further, surface-topography of the machined surface was critically examined using scanning electron microscopy and three-dimensional non-contact roughness tester. Graphene nano powder concentration (0.3 g l−1) increased the MRR around 68% compared to coconut biodiesel (BD). A medium order of capacitance (10 nF) offered a maximum MRR irrespective of dielectric used. With higher order capacitance, the minimum TWR is obtained due to longer pulse off duration. High surface finish is achieved with graphene nano powder dispersed coconut BD due to uniformly distributed of craters on the machined surface. Recast layer thickness is 3.08 μm, 1.62 μm and 2.34 μm with coconut biodiesel, 0.3 g l−1 and 0.6 g l−1 graphene particles mixed coconut biodiesel, respectively. Minimum recast layer is observed with graphene particles mixed coconut biodiesel under considered parametric conditions due to lesser eroded particle deposition. EDS results confirm that the sedimentation of graphene nano powder (increase in carbon %) on work surface results in increase in hardness. Crater size, voids and cracks were reduced with graphene nano powder dispersed coconut BD due to uniform distribution of heat energy over machining region. Results showed that the graphene nano powder mixed coconut biodiesel can be the substitute for mineral oil.