Investigation of Powder Mixed EDM of Nickel-Based Superalloy Using Cobalt, Zinc and Molybdenum Powders

Abstract

Powder mixed electric discharge machining is one of the important recent trends in electric discharge machining process which successfully addresses some of the issues associated with the normal die-sinking EDM process. Since the performance of powder mixed EDM is based on work and tool material combination besides other process parameters, various research works have been reported by experimenting with different materials. This work aims to study the influence of different tool materials on powder mixed EDM of a nickel-based superalloy, Nimonic 75, along with using three different powders (zinc, Co and Mo). Nimonic 75 material is being widely used in aerospace and high-temperature applications. Besides the powders type and tool material (Cu, brass and W), the other process parameters are concentration of powder (Cp), peak current (Ip) and pulse on time (Ton). The performance measures considered in this study are material removal rate (MRR), tool wear rate (TWR) and surface roughness (SR). The experiments were conducted based on Taguchi’s orthogonal array (L27 313). Using ANOVA, it was identified that peak current and tool material had much greater influence over MRR, TWR and SR. Zinc powder yielded highest MRR, and molybdenum powder produced good finish of the components. It was also observed that copper yielded highest MRR, tungsten experienced low TWR, and brass tool electrode produced very smooth surface finish.