FE Modeling for Single Spark in EDM Considering Plasma Flushing Efficiency

Abstract

Due to complex nature of single spark phenomenon in EDM, the removal mechanism needs better comprehension and clarity. In this context, this work presents a finite element simulation of a single spark during electrical discharge machining taking into consideration significant aspects such as temperature dependency of material properties, Gaussian distribution of heat flux, plasma channel radius varying with current and discharge duration, and variability in factors such as cathode energy fraction, and plasma flushing efficiency. Such a model can offer a better prediction of the crater profile obtained on the work surface which enables it to be extended to multi-spark scenarios for predicting the surface texture obtained through EDM process. FE simulations showed that the crater radius and crater depth increases with increasing values of the operating parameters such as discharge current and pulse on-time. It is also observed that the crater aspect ratio (rc / dc), which is the ratio between crater radius and crater depth, shows a high value at low values of discharge current and pulse on-time. This is due to feeble penetration of heat through the cathode body for low values of the operating parameters. The validation of the FE model is made against experiments and it was found that the model displays improved prediction at high values of the operating parameters. The error in prediction of rc / dc by the model varies from 9.1 to 13.4 % which represents a good prediction of crater profile by the model.