Factor influencing the gas film performance of electrochemical discharge machining

Electrochemical discharge machining (ECDM) is found to be a potential process for fabricate micorholes and microchannels in electrically nonconductive material. In the ECDM process, the gas film of electrode surface is used as the dielectric medium required for the spark discharge. Therefore the gas film quality is the dominant factor that determines the machining quality such as geometric accuracy, surface roughness and repeatability. In this study, various parameters were induced to investigate the influence on the gas film quality and that which accounted by the produced current signal and machined contours. Experimental results showed that a stable and dense gas film could be obtained as the machining voltage exceeds critical voltage and reached a characteristic value, which is called "transition voltage" in this study. Under transition voltage(38 V in 6 M KOH), a stable electrochemical discharge current could be generated and resulted in a smallest deviation of contour dimension. Besides, the paper proposed that the change of current signal could serve as a standard of judgment. And this method could serve as an evidence for making subsequent improvement of process.