Prevention of Material Deterioration in ECM of Sintered Carbide with Iron Ions

Abstract

This study focuses on electrochemical machining as a method of processing sintered carbide at high speeds. Previous studies have suggested the possibility of using electrochemical machining to achieve high-speed machining of sintered carbide. However, there has been strong resistance in industry against bringing sintered carbide into contact with a conductive liquid. This is because the material quality of sintered carbide is degraded by the elution of Co when it is brought into contact with a conductive liquid.

In previous reports, the authors have shown that it is possible to control two modes of Co elution occurring during electrochemical machining: the elution from sintered carbide when it comes into contact with an electrolyte, and the selective elution of Co due to difference in the speeds of WC dissolution and elution of Co when sintered carbide is connected to an electrical source for processing. It was shown that it is possible to control the elution Co in sintered carbide when it comes into contact with an electrolyte by adding Co ions to the electrolyte to increase the concentration of Co ion, and that it is possible to prevent the excessive elution of Co by using a bipolar electrical source for machining. Although we showed that it is possible to carry out electrochemical machining of sintered carbide without degrading its quality, adding of large amounts of Co ions to the electrolyte entails a high cost. In this report, therefore, we describe the addition of Fe ions instead of Co ions to perform electrochemical machining of sintered carbide without quality degradation.