Current Distribution during Short Circuits in Electrochemical Machining

Short circuits are the most significant process defects in electrochemical machining. They can occur seemingly randomly when machining on the edge of stability, which is done for productivity reasons. In many applications the occurrence of this event causes the workpiece to be declared scrap. In order to clarify whether this measure is necessary, the short circuit event and its effect has to be investigated and understood. Since there are several orders of magnitude between the active area and the short circuit area, it is important to determine the distribution of the current in the short circuit event between these two areas. To answer this question, this article describes the experimental setup that was developed to measure this distribution. To ensure good quality of the measurements, several tests have been conducted. It was found that only the excessive amount of energy, if compared to a stable process, is transferred through the short circuit. It is therefore also only this energy that is responsible for the damage caused to the workpiece. Especially when machining large surface area workpieces this will reduce the impact the short circuit event has on the quality of the surface and might be one step to reduce the number of parts declared defective after the occurrence of a short circuit event.