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

Abstract

Micro-EDM has its potential in micro tools and parts manufacturing. However, the machining speed is quite low due to short-circuits and abnormal discharges, because of the difficult debris removal from the narrow gap-width. Especially, hole drilling process becomes impossible under an ultra-small discharge energy condition, such as a low open voltage and the stray capacitor 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 effect of vibration on the machining characteristics of micro-hole drilling under the ultra-small discharge energy condition was investigated. It was found that a significant increase in the machining speed was realized by applying ultrasonic vibration to the machining fluid. Also, with the vibration to the machining fluid, micro-hole drilling with ultra-small discharge energy became possible. Additionally, the experimental results show that the lateral gap-width between the tool electrode and workpiece was shortened, and the tool wear ratio became smaller.