Optimizing electric discharge machining parameters for tungsten-carbide utilizing thermo-mathematical modelling

Abstract

The energy distribution in the Electrical Discharge Machining (EDM) process influences the material removal rate, and other machining characteristics like crater geometry, relative wear ratio and surface roughness. During this process the electrical energy is converted into heat energy and this energy is distributed among the electrode, workpiece and the dielectric fluid. The fraction of the energy which is transferred to the workpiece, is the useful energy and this energy should be maximum, for optimum utilization of energy. This fraction of energy is one of the important parameters used in the existing thermo-physical models of EDM process. Due to apparent incongruities and conflicting data early researchers conjectured the same value of fraction of energy transferred to electrodes for all machining parameters in their models for numerically calculating the volume and geometry of the crater formed. This assumption is one of the reasons of error in the models from the experimental data. So this study is planned to experimentally study the variation of this fraction of input discharge energy with the help of thermo-mathematical models during EDM of Tungsten-Carbide by varying the machining parameters current and pulse duration. The data calculated in this study can be further used in the existing thermo-physical models, expecting to bring the models preciously more close to the real conditions. This data will also be helpful for numerically calculating the optimum parameters using optimum value of the fraction of energy transferred to the electrodes especially workpiece. The results obtained showed that the energy effectively transferred to the workpiece varies with the discharge current and pulse duration from 6.5% to 17.7%, which proves that the fixed value assumed in the models is not in line with real EDM process.