Influence of the spark heat on the electrode behavior in Powder Mixed-EDM environment

Abstract

Most past studies did not attempt to improve the numerical model for the electrode removal rate which depends on the experimental results. Furthermore, these studies have not included the damage-sensing for the electrode in Powder Mixed-EDM (PMEDM) medium. Therefore, the current study aims to enhance this model for the copper electrode based on the heat flux for the spark channel. Besides, it focuses on sensing the copper electrode damage depending on the slope relation between eroding velocity and the pulse duration. In both studies, during machining D2 steel, Nano chromium powder in the dielectric liquid is applied. The correlation factor between the Numerical Heat Flux q(r) and the experimental results for the Tool Wear Rate (TWR) attained is 93.06%. The value of this factor improves the mathematical model for TWR instead of the traditional mechanism that adopts the crater volume. Also, the damage-sensing constant (STD) in the copper electrode is very efficient at the minimum value of the peak current (IP), powder concentration (PC) and the maximum level of the pulse duration (Ton). Thus, the statistical confirmation using Response Surface Methodology (RSM) produced a higher value of the composite desirability (96.76%) and error percent equals to (10.3%-1.55%) and (0.18%-2.40%) for TWR and q(r), respectively. On the other hand, the optimum operation values are IP = 10 Amps, Ton = 30 µs, and PC = 2 g/L. These confirmation values are similar to the trials No. (3) and No. (11). Therefore, these values confirm the main purpose in order to obtain the best performance for TWR at the minimum spark heat.