Detection of EDM Spark Location by Measuring Potential Difference on the Electrode

This paper describes a method for detecting spark locations in EDM processes. The method, named the potential difference method, consists of supplying discharge current through branched electric wires, each of which is connected to each end of a tool electrode, and detecting the potential difference between the connecting points. The spark locations can also be detected by the “current method” formerly developed by this research group, which compares the different values of currents supplied through the branched wires. In this method, however, the detection sensitivity is strongly decreased when the pulse duration is short, when the length of the branched electric wires is long, or when the specific resistance of the electrode is small. In this research, the characteristics of the two methods were studied theoretically and experimentally. The results show that the sensitivity of the potential difference method is not affected by the pulse duration, the length of branched wires, or the specific resistance of the electrode.