Influence of WC and Co on machinability in mist and dry cutting of cemented carbides

Cemented carbides are sintered metals consist of hard particles (WC, TiC, TaC, etc) and metallic binder. They have high hardness and strength even at high temperature, and are used for not only cutting tools but also forming rolls, dies and so on. They are well known as difficult-to-cut materials. The tool wear is so severe in cutting with a diamond tool that grinding is commonly used for finish machining. As the results, the productivity becomes low and the production cost becomes high. In previous study, using with PCD (Poly-Crystal Diamond) the relationship between tool life and cutting conditions was made, clear. For example, the tool life became shorter with the increase of the feed rate, and the tool life was independent of the depth of cut. Recently, the demand of the cemented carbides is increasing. In order to get high productivity, cutting finish is desirable instead of grinding. In this paper, three kinds of cemented carbides were turned with the PCD tool. And the influence of WC and Co on the machinability in dry and mist cutting was investigated in detail. As the result, the tool wear depended on the WC contents, and the lubricating action restrained the flank wear in the mist cutting. Summary of results are shown as follows: (1) In mist cutting of cemented carbides, the more the WC was included, the longer the tool life becomes. (2) The more the WC was included, the more chip shape becomes irregular.