EDM at Low Open-Circuit Voltage

The possibility of EDM at open-circuit voltages of lower than 30V has been examined using an RC circuit, because low voltages are preferable in terms of machining accuracy; however, machining at such voltages had not been attempted before. EDM of holes in copper is carried out with tungsten electrodes of 15μm or 7μm diameter to investigate the machining rate. At open-circuit voltages of 5V or higher, the average electrode feed speed, which is defined as the feed per machining time, is higher than 5μm/min under certain electrical conditions. Although the machining rate is very low, machining is possible even at an open-circuit voltage of 2V. These voltages are much lower than those usually used for EDM. A tungsten rod of 1μm diameter can be fabricated at an open-circuit voltage of 20V by wire electrodischarge grinding (WEDG), indicating the possibility of future applications of EDM to submicron machining and nanomachining.