FAILURE OF TUNGSTEN CARBIDE COBALT ALLOY TOOLS IN MACHINING OF CARBONMATERIALS

Sintered carbon and carbon fibre reinforced plastic composites are oft en used for functional and structural materials. This paper outlines t he machining of these materials using cemented tungsten carbide-cobalt tools. The influence of WC grain size and Co content on tool wear rat e when machining carbon materials has been examined and the results co mpared with those from rubbing tests. In addition, the failure process is discussed from the viewpoint of brittle fracture probability. The main results are as follows. (1) As WC grain size increases, tool wear rate decreases, in spite of a reduction in tool hardness. (2) A decre ase in Co content leads to a decrease in tool wear rate. (3) The failu re of WC-CO alloy tools is due mainly to the loss of WC particles. Thi s failure process can be fundamentally explained by the probability of brittle fracture.