A Study on Pulse Generator for Micro WEDM of Polycrystalline Diamond
This paper presents a new pulse generator for cutting of polycrystalline diamond (PCD) by micro wire-EDM. Three pulse control methods (AC power supply pulse control method, fixed pulse width modulation pulse control method and improved AC power supply pulse control method) have been proposed to achieve high frequency and low energy discharge pulses. The improved AC power supply pulse control method enables the pulse generator to provide a period of 20 μs off duty cycle followed by a period of duty cycle for reionization of the dielectric in the spark. Compared to the other two methods, the improved AC method can provide smaller peak current and discharge duration and thereby achieve a smaller slit width and better surface finish. Tests revealed that the developed power supply using anti-electrolysis circuitry and a digital signal processor-based pulse control circuit can provide very low discharge energy pulses with a frequency of 200 KHz, discharge duration of 0.75 μs and a peak current of 3 A. Experimental results demonstrate that the proposed pulse generator can achieve a feed rate of 0.4 mm/min, a surface finish of 0.53 μm Ra and a damaged layer of 5 μm on PCD surface through proper machining settings.
W.B. Lee, C.F. Cheung and S. To
M. T. Yan et al., "A Study on Pulse Generator for Micro WEDM of Polycrystalline Diamond", Key Engineering Materials, Vol. 516, pp. 498-503, 2012