Optimizing the powder mixed EDM process of nickel based super alloy

Abstract

Powder Mixed Electric Discharge Machining has been the main focus of many researchers for quite a long time. The performance of EDM process has been improved significantly by using powder mixed dielectric medium. Numerous researches were undertaken to study the influence of different process parameters involved in the powder mixed EDM by experimenting with different work materials and powder combination. The objective of this work is to conduct experimental study on the powder Mixed EDM of a Nickel based super alloy, Nimonic 75, using three different powders which are graphite, silicon and manganese. The other important process parameters considered are concentration of powder (Cp), peak current (Ip), duty factor (DC). The experiments were conducted based on the Response Surface Methodology (RSM) design. The important measures of performance of EDM process chosen in this study are Material Removal Rate (MRR), Electrode Wear ratio (EWR) and Surface Roughness (SR). Graphite powder yielded highest MRR and silicon powder produced good finish of the components. The influence of powder at higher concentration is not significantly high. Moreover, Higher duty cycle caused the decrease of MRR, EWR and increase of SR. This works also aims to optimize the process parameters using Grey Relational Analysis (GRA) combined with Fuzzy logic method. The optimum conditions identified based on GFRG was powder = Mn; concentration = 3 g/l; discharge current = 4 A and duty cycle = 0.9 It was also estimated that the error in predicting best output of the PMEDM process is below 6%.