Investigation of Machining Characteristics of Micro-EDM with Ultrasonically Vibrated Machining Fluid under Ultra-small Discharge Energy

Micro-EDM has its potential in the manufacture of micro tools and parts. However, the machining speed is low owing to short circuit and abnormal discharge, because of the difficulty in removing debris from the narrow gap-width. In particular, hole drilling becomes impossible under ultrasmall discharge energy conditions, such as the low open voltage and stray capacitance in the RC discharge circuit. In this study, the effect of applying ultrasonic vibration to the machining fluid in micro-EDM was experimentally investigated, in order to realize a higher machining speed in the deep hole drilling process. Furthermore, the effects of vibration on the machining characteristics of micro-hole drilling under the ultrasmall discharge energy condition were investigated. It was found that a significant increase in machining speed was realized by applying ultrasonic vibration to the machining fluid. Also, with the application of vibration to the machining fluid, micro-hole drilling with ultrasmall discharge energy became possible. Additionally, experimental results show that the lateral gap-width between the tool electrode and the workpiece, as well as and the tool wear ratio, became smaller.