Improvement of processing quality based on VHF resonant micro-EDM pulse generator

Abstract

As an important non-traditional machining technology, micro-electrical discharge machining (micro-EDM) has become one of the ideal methods for conducting material parts in the mesoscopic scale. However, the current micro-EDM pulse generator has low discharge frequency and wide pulse width, and its nano-scale high-efficiency erosion ability is still difficult to meet the increasing practical requirement. For this purpose, a micro-energy pulse source with narrow pulse width and high-voltage amplitude, which is different from the current typical micro-energy pulse generator, is designed for a pulse generator with more fine-etching ability. Using the principle of circuit resonance, the very high-frequency (VHF) resonant discharge pulse generator can produce an open-circuit voltage waveform with a discharge frequency of 90 MHz and a peak value of 70 V. The single-pulse discharge energy can be continuously processed as low as 6nJ. Based on the VHF pulse generator and the transistor-type pulse generator, the discharge erosion experiments are carried out, and the surface roughness and recast layer are analyzed and compared. The experimental results show that the former processing quality is obviously better than the latter. The surface roughness after processing at a discharge frequency of 90 MHz can reach Ra 42 nm, the average diameter of craters is 0.38 μm, and the hole edge processed at a discharge frequency of 55 MHz has almost no recast layer which achieves similar cold processing effects.