Study on Electrochemical Machining of Sintered Carbide

In this study, ECM phenomena of sintered carbide are investigated. The previous study has shown that sintered carbide which is a composite body of WC and Co can be machined by ECM at high speed. However, many problems remained to be solved preventing the practical application. Authors consider that one of the biggest problems in ECM of sintered carbide is the elution of cobalt: the binder of the material. When too much cobalt elution occurs, the strength of the material deteriorates making it unsuitable to be used as a die, especially, for cold forging. In this report, methods for the prevention of Co elution are discussed. First, an experiment was conducted using a beaker which indicated the possibility of inhibiting cobalt elution by adding Co ion to the electrolyte. Second, a machining experiment was carried out using electrolyte with added Co ion. The result showed that sintered carbide can be machined without excessive Co elution. Then relationship between machining current, surface quality, and machining speed were also investigated.