Study of gas film characterization and its effect in electrochemical discharge machining

Electrochemical discharge machining (ECDM) is a promising method for the machining of hard, brittle, and inert materials such as ceramics and glass. Reducing the overcut is an important requirement for the ECDM process to emerge as a viable micro manufacturing method. The gas film quality is a critical factor contributing to the machining overcut in ECDM. This study focuses on the characterization of the gas film thickness and stability in ECDM. A full factorial parametric study of the gas film was performed for the electrolyte concentration, level of the electrolyte, the distance between electrodes and time of machining. Analysis of variance of the gas film thickness and stability of the gas film along with experimental verification revealed that the overcut in ECDM is affected by both gas film thickness and stability of the gas film. A lower concentration of electrolyte, with a lower level of electrolyte above the top surface of the workpiece and a higher distance between electrodes, for a lower time of machining constitute optimal machining condition to machine holes with less overcut and less taper.