Observation of Machining Phenomena by Single Pulse Discharge

The electrical discharge machining (EDM) process exhibits variations in discharge timing and debris removal timing depending on various machining conditions and environments, making it challenging to establish a universally optimal setting. If the material removal mechanism could be fully elucidated, it would become possible to control the timing of debris removal, thereby enabling the efficient conversion of discharge energy into material removal energy. Understanding the material removal mechanism has the potential to facilitate high-efficiency machining and achieve high-precision finishing using EDM techniques. In this study, three distinct phenomena occurring during single pulse electrical discharge were observed: discharge arcs, debris ejection, and shock waves. For the observation of debris ejection, a light source with higher brightness than the discharge arc was employed, and a band-pass filter was used to visualize the debris as shadows. The observation of shock waves was conducted using the Schlieren method. It was confirmed that material removal occurs multiple times within a single discharge pulse. Additionally, shock waves were observed coinciding with the ejection of debris. This report presents an investigation into the relationship between the number of debris ejection events during the material removal process, the volume of material removed from discharge craters, and the surface area of the resulting craters.