Electrical Discharge Machining using Copper Electrode made by Additive Manufacturing
Daisuke Yanagida, Takayuki Nakamoto, Hisashi MINAMI, Takao Miki, Sohei Uchida, Takahiro Kimura, Kôji Watanabe
Abstract
In electrical discharge machining (EDM), it is important to evacuate EDM debris from the discharge gap for machining stability and accuracy. Especially in the processing of deep slots with high aspect ratio, EDM debris accumulated in the bottom of the groove often causes short circuit and false discharge, resulting in process instability. The tool electrode having micro holes for the machining fluid, which flush debris out of the discharge gap, enables efficient EDM machining of the deep slots. However, in conventional machining, it is difficult to drill high aspect ratio micro holes. Recently, the additive manufacturing (AM) technologies with the selective laser melting (SLM) method using metal powder attracts attention as a promising technique which can produce various complicated shapes efficiently. By using the AM method, it is possible to fabricate a high aspect ratio EDM electrode with micro holes inside. This paper describes the application of electrodes fabricated by the AM method to electrical discharge machining. Almost fully dense additive manufactured copper electrode (AM-Cu electrode) having more than 99.7% relative density was obtained by optimizing the laser scanning parameters for Cu-1.3mass%Cr (Cu-Cr) alloy powder. EDM properties of the AM-Cu tool electrode and the machinability of deep rib slots by using that electrode with micro holes inside were investigated. As a result, it was confirmed that EDM properties of the AM-Cu tool electrode were almost the same as those of conventional Cu tool electrode. Moreover, it was shown that use of the AM-Cu tool electrode with micro holes inside was found to shorten the processing time and improve machining accuracy significantly compared with the conventional solid Cu tool electrode.