Spark radius modeling of resistance-capacitance pulse discharge in micro-electric discharge machining of Ti-6Al-4V: an experimental study

Several modeling and simulations have been reported to characterize the electric discharge machining (EDM) and micro-electric discharge machining (micro-EDM) processes. However, these models have been considered spark radius as a function of time or time and current as well as these models are valid only for transistor-type pulse discharge circuits. Therefore, it is important to develop an accurate model to predict the spark radius for RC-relaxation circuits where capacitance and voltage are the important process parameters. In this paper, an attempt has been made to develop a mathematical model predicting the single-spark radius produced during micro-EDM of Ti-6Al-4V. A series of experiments were conducted based on three-level full factorial experimental design with four center point runs. Capacitance and voltage were taken as the variable factors and spark radius was measured as the response. Based on the experimental results, the effect of capacitance and voltage on spark radius was studied in detail with analysis of variance. The results showed that capacitance significantly influenced the spark radius compared to voltage. In addition, a mathematical model has been developed to correlate the capacitance and voltage with spark radius by adopting regression analysis. Finally, the developed model equation was validated with confirmatory experiments and the predicted and experimental spark radius was found to be in good agreement with a prediction error less than 5 %.