Design, analysis and experimental study of a high-frequency power supply for finish cut of wire-EDM

Abstract

This paper presents the development of a high-frequency power supply for surface quality improvement of wire electrical discharge machining (wire-EDM). A novel fixed pulse-width modulation pulse control method is proposed to generate high-frequency and short-duration pulse control signals. A spark gap model using a resistance–capacitance (RC) circuit and a Zener diode is proposed for circuit design and simulation analysis. Tests revealed that the developed power supply using anti-electrolysis circuitry and digital signal processor-based pulse control circuit can provide very low discharge energy pulses with a frequency of 4.4 MHz, discharge duration of 90 ns and a peak current of 1.2 A. Experimental results demonstrate that a pulse duration ratio (defined as a ratio between pulse duration of positive polarity and that of negative polarity) of three can reduce the electrolytic effect of tungsten carbide for the machining conditions of high discharge frequency more than 500 kHz.