Adaptive control of the WEDM process using the fuzzy control strategy

The proportion of abnormal sparks (abnormal ratio) and the sparking frequency are employed to monitor and evaluate the gap condition of the wire electrical discharge machining (WEDM) process on-line. The relationships are investigated between these two sensing parameters and wire breaking phenomenon, metal removal rate (MRR), and surface roughness of the machined part under various machining conditions. Based on the results, an adaptive control optimization (ACO) system is developed. Fuzzy rules based on operator experience and expert knowledge are constructed, and a multivariable and three-region fuzzy controller is designed and implemented. By regulating the servo feed and the pulse off-time in real time, the abnormal ratio is controlled at a predetermined value for optimum and stable machining, while at the same time the sparking frequency is kept under a critical value for wire rupture prevention. Experimental results demonstrate that the developed control system results in very satisfactory performance.