Abstract Cutting experiment on hard plastic PMMA was conducted with PCD and CVD cutter respectively.The edge and surface morphology and composition of the PCD and the CVD diamond insert,as well as the surface roughness,were studied before and after the cutting process.The cutting performance of these tools was compared and their failure mechanism was explored.The results showed that under the same machining condition,the cutting performance of the CVD diamond tools was superior to that of the PCD tools.The main failure mechanism of the PCD tools is the chemical reaction between binder and machined material,which leads to the loss of binder and the abscission of worn particles(diamond particles),and then induces the damage of the cutting tools structure.The failure mechanism of the CVD diamond tools is the wear of affected layer.With further extension of the cutting process,the temperature of the cutting zone keeps rising.When the temperature reached the thermal chemical reaction temperature,affected layers would be generated at the tool surface as the insert abraded out;at the same time,the tools'wear may also be caused by the fatigue failure of the grain boundary of CVD diamond at high temperature.

Keywords PCD insert;CVD insert;cutting performance;failure mechanism

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