Experimental and statistical investigation into micro-EDM of Hastelloy-X using PVD diamond coated and AlTiN coated tungsten carbide electrodes

This paper investigates the effectiveness of electrode coating during the micro-electro-discharge machining (micro-EDM) of a nickel-based Hastelloy X (Ni-X) using uncoated, physical vapour deposition (PVD) diamond-coated, and aluminium titanium nitride (AlTiN)-coated tungsten carbide tool electrodes. The Box-Behnken design (BBD) along with response surface methodology (RSM) was used for modelling the effect of different machining parameters, i.e., capacitance, voltage, tool rotational speed, and tool coating on the micro-EDM performance of Ni-X alloy. The micro-EDM performance was evaluated by machining time, tool wear, crater size and surface microhardness. Capacitance and voltage were found to have significant effect on machining time, tool wear and crater sizes. Increasing capacitance and voltage reduced the machining time as well as tool wear however, crater size was increased indicating rougher machined surface at higher capacitance and voltage settings. [Submitted 19 November 2018; Accepted 18 June 2019]