Comparison of Cutting Performance and Failure Mechanism of PCD and CVD Diamond Tools

Through the cutting experiment, the surface and edge shape of the tool before and after cutting, the composition of the diamond blade and the surface roughness of the workpiece were observed. The cutting performance of the two tools was compared and the failure mechanism was discussed. The results show that under the same conditions, the cutting performance of CVD diamond tools is significantly better than that of PCD tools. In the turning process, the failure mechanism of the PCD tool is mainly due to the chemical reaction between the bonding agent and the chemical components in the material to be processed, so that the bonding agent is lost, resulting in loose structure of the tool, which leads to the falling off of the abrasive particles. The failure mechanism of a CVD tool is to produce deteriorated layer wear. As the processing time is further extended during the cutting process, the temperature of the cutting zone is continuously increased. When the thermochemical reaction temperature is reached, a metamorphic layer is formed on the surface of the tool, which causes the wear of the tool during the cutting process. At the same time, the CVD is performed at a high temperature. The fatigue failure of the grain boundary of diamond may also cause wear and tear of the CVD diamond tool. (Diamond and Abrasives Engineering, 2009, Issue 1)

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 PC D tools. The main failure mechanism of the PC D tools is the chemical reaction between binder and machined material, which leads to the loss of binder and the abscission of wearing 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.