Multi-spark numerical simulation of the micro-EDM process: an extension of a single-spark numerical study

Abstract

The micro-electric discharge machining (micro-EDM) process had been studied by a number of researchers incorporating the single-spark numerical simulation technique. However, due to the stochastic nature of spark generation, complexities arise in determining the precise location of sparks and exact crater overlapping. Owing to this randomness, modelling of the micro-EDM process using the multi-spark approach has not been attempted hitherto. In this research work, an endeavour has been made to propose an improved concept of occurrence of sparks based on a minimum inter-electrode gap presented by the randomly assigned surface roughness to the tool and workpiece electrodes. The inadequacies associated with the single-spark modelling of the micro-EDM process can be overcome to a larger extent by deterministic estimation of the distinct spark location. The essential crater dimensions are inferred from single-spark simulation to estimate the exact number of sparks essential for the removal of a single layer in the multi-spark simulation. Numerically simulated single-crater dimensions are validated with the experimentally determined crater. Further, multi-spark simulation is performed, and successive layers are removed from the workpiece to generate a feature with a certain depth. The effect of the thermophysical properties of workpiece materials (copper, SS-EN 24, and Ti-6Al-4V) on the linear material removal rate (MRRl) is analysed. Simulation results illustrate that among the three materials, Ti-6Al-4V and SS-EN 24 result in the highest and lowest MRRl, respectively. The multi-spark approach presented in this work essentially differs from the occurrence of multiple sparks from a single-pulse input.