Threshold technology and its application for gap status detection

Process control systems of modern EDM-machines offer several opportunities for gap status detection. The method described here is the threshold technology at which the voltage course of a discharge can be classified in normal pulses, open circuits, short circuits and arcs by different voltage thresholds in combination with time recording. Especially in arc detection a new path will be treated by using a burning voltage threshold positioned slight below the effective burning voltage of a normal discharge. Its determination depending mainly from the electrode/workpiece material combination and the adjusted amperage will be described in detail. Moreover a fuzzy gap width control system will be established only based on the relative number of open and short circuits ascertained within a time period. Also in this case the threshold technology will be applied. This gets completed by a neural network. The efficiency of the different systems will be demonstrated at roughing and smoothing experiments in comparison to a ignition delay time (td)-based solution.