Investigations on the relationship between surface roughness and process variables of die sinking electro-discharge machining

Abstract

Achieving a high-quality surface finish in electro-discharge machining (EDM) poses challenges compared to other machining methods. It necessitates separate finishing operations following one or more roughing stages. The precise connection between surface roughness and the influencing factors remains unclear. Existing literature tends to prioritize material removal rates and relative electrode wear over surface roughness. Additionally, previous investigations into evaluating surface roughness performance in die sinking EDM have typically examined only a limited number of variables at a time, despite the involvement of multiple parameters in the process. In the present work, a deeper understanding of how process variables impact surface finish quality were studied. Experiments were conducted on die steel workpieces, varying seven key parameters: pulse current, pulse width, gap voltage, dielectric flow rate, tool material, duty cycle, and servo feed, with the goal of achieving a superior surface finish. To assess the significance of these controlling variables and their interactions, the experimental results were analyzed using ANOVA (Analysis of Variance). Subsequently, a generalized equation is developed that elucidates the relationship between surface roughness and process variables. Furthermore, confirmatory tests were conducted to validate our chosen methodology.