An on-line monitoring system for micro electrical discharge machining (micro-EDM) process

A pulse type discriminating system to monitor the process of Micro-EDM is developed and implemented. The specific features are extracted and the pulses from a RC type power source are classified into normal, arc, transient short circuit, and complex types. An approach to discriminate the pulse type according to three durations measured at three pre-determined voltage levels of a pulse is proposed. The developed system is verified by using simulated signals. Discrimination of the pulse trains in actual machining processes shows that the pulses are mainly normal type for micro wire-EDM and micro-EDM milling. The pulse type distribution varies during the micro-EDM drilling process. The percentage of complex type pulse increases monotonically with the drilling depth. It starts to drop when the gap condition is deteriorated. Accordingly, an on-line monitoring strategy for micro-EDM drilling process is proposed.