Improving the machining efficiency in electrochemical discharge machining (ECDM) microhole drilling by offset pulse voltage

Recently, the utilization of pulse voltage has proved to be a potential method for improving the machining accuracy in the microdrilling process by electrochemical discharge machining (ECDM). Although pulse voltage is favorable for improving the machining quality, it is hard to obtain an efficient machining rate. The pulse-off (T_off) duration allows the gas film structure to be re-constructed, which makes the sustainability of a dense gas film difficult and results in unstable and unpredictable discharges. In this study a novel pulse voltage configuration, called offset pulse voltage, has been designed and applied in the ECDM process to improve gas film stability. The offset pulse voltage adds a constant voltage, called offset voltage, at T_off duration to enhance gas film stability and to further promote the discharge performance. The experimental results demonstrated that the increase in offset voltage at the pulse-off duration generates more stable discharges when compared to those generated by the conventional pulse voltage. Results also show that both the mean machining time and time deviation are decreased around 60% without sacrificing machining accuracy by an adequate offset voltage.