Analysis of Fundamental Process Characteristics for Sinking-EDM of Cemented Carbides as a Function of Polarity

Abstract

Cemented carbides have a growing potential as a tool material in metal forming due to their great resistance to wear and increased compressive strength. The further spread for active elements in metal forming is conflicted by high costs and a lack of knowledge about the specific performance and interpretation of the applicable regulations. A key technology for the machining of cemented carbide forming dies is Electrical Discharge Machining (EDM) because of a difficult conventional machinability and specific material properties. However, machined carbide tools often show a toughness remaining below expectations. A possible explanation could be the extent of the manufacturing process related thermally affected rim zone. In addition, the polarity needs an evaluation for a basic understanding in regard to MRR. Therefore, a cemented carbide, a version with normal binder phase content, and a common tool steel as standard material are compared focusing on the material removal rate and formation of cracks in the rim zone for different polarizations.