Characteristics of different Transparent and Conductive Materials Applied for Observation of ECM Gap Phenomena

In electrochemical machining (ECM) processes, bubbles and sludge of metal oxides are generated in the gap. These products may influence the conductivity of electrolyte and the current distribution on the surface of workpiece, which directly influence the machining accuracy of ECM. In order to improve the machining accuracy, it is necessary to elucidate the gap phenomena of ECM. In this study, to investigate the mechanism of the change in the current density distribution, the gap phenomena were directly observed from the direction normal to the machining surface by a high speed video camera through the electrode made of transparent material such as SiC and ITO glass, which are optically transparent and electrically conductive. The influence of characteristics of transparent electrodes on the observation phenomena were compared. Moreover, the similarity of observed phenomena using different transparent electrodes to the actual ECM process was discussed.