The Quantitative Research of Size Effects in Piezoelectric Self-adaptive Micro-EDM

Abstract

Piezoelectric self-adaptive micro electrical discharge machining (micro-EDM) is a new micro-EDM technology, which is based on inverse piezoelectric effect. Compared to conventional micro-EDM, piezoelectric self-adaptive micro-EDM can obtain better machining performances by facilitating the ejectment of debris and reducing the abnormal discharge. However, micro size effects also occur in piezoelectric self-adaptive micro-EDM, which can result in the difficulty to predict and optimize the machining results. In this paper, the working principle and advantages of piezoelectric self-adaptive micro-EDM are presented and the theory of similarity is introduced to quantify the size effects. The evolutions of machining time and tool wear length of micro-EDM with and without piezoelectric actuator are evaluated by discussing the similarity precision and similarity difference. It is found that the similarity precision and similarity difference increase with the decrease of the scale of the open-circuit voltage, regardless of whether the micro-EDM is with or without piezoelectric actuator. It is indicated that micro-EDM is more susceptible to the size effects in the case of machining with lower open-circuit voltage. Both the similarity precision and similarity difference of machining time of micro-EDM with piezoelectric actuator are lower than those of conventional micro-EDM. It is concluded that the smoother machining process of piezoelectric self-adaptive micro-EDM can result in a weaker size effects, so the machining performances of piezoelectric self-adaptive micro-EDM are easier to be predicted. The similarity theory is an effective method for investigating the size effects in the micro-EDM.