Wear of micro diamond tool in ultra-precision turning under dry and minimum quantity lubrication conditions

Minimum quantity lubrication (MQL) is an effective way to reduce the cutting temperature and tool wear. To reveal the effect of MQL on the wear of micro diamond tool, a calculation model for the cutting temperature of micro diamond tool under dry friction condition is established firstly by using the Fourier’s law of heat conduction. Regarding the boundary film as a layer of heat-conduction medium, a revised calculation model for the temperature distribution on tool rake face under MQL condition with different cutting fluids is further established. The predicted results indicate that low viscosity is beneficial to the wetting of cutting fluid on tool-chip contact interface, which can relieve the friction. The reduction of friction finally decreases the cutting temperature. Secondly, the cutting temperature–dependent wear volume of micro diamond tool is predicted by using the Usui wear rate model in response to different cutting fluids and different cutting distances. In dry cutting, the graphite wear of micro diamond tool prevails. However, the application of MQL can slow down the graphitization of diamond, so the wear of micro diamond tool visibly decreases. Finally, cutting experiments with different cutting fluids are performed to verify the established models. The experimental observations agree well with the theoretical prediction results. Such satisfactory consistency confirms that the cutting fluid with low viscosity can reduce the cutting temperature and inhibit tool wear effectively.