Research of lower tool electrode wear in simultaneous EDM and ECM

Abstract

Tool electrode wear is a key factor influencing shape accuracy in electrical discharge machining (EDM). In the process of drilling blind holes, wear constantly reduces the length of the tool electrode. As a result, when eroding down to a fixed depth, the real depth of the hole will be significantly smaller. The problems created by tool electrode wear become more complicated when machining complex three-dimensional micro-cavities. Performing electric discharge in deionized water can get less tool electrode wear compared with traditional EDM. However, this process causes excessive electrolytic-erosion and workpiece surface damage as slight electrical conductivity always exists in deionized water. In this manuscript, a new method to reduce the electrode wear and suppress excessive electrolytic-erosion is investigated. Electrolyte with a much higher conductivity than deionized water is utilized as machining fluid in the method, while electro-deposition is used to compensate for tool electrode wear in the processing. Besides, nanosecond voltage pulse and tool electrode with side-insulation are adopted to suppress excessive electrolytic-erosion. Experiment results show that this new method can reduce electrode wear and suppress excessive electrolytic-erosion effectively.