Investigation of the surface profile along the cutting trajectory and its correlation with cutting forces in single point diamond turning

Surface roughness is one of the key parameters affecting the surface finish quality in ultra-precision turning. As conventional surface roughness measurement is merely a statistical representation of the surface condition, it does not represent the dynamic relative movement between a workpiece and a tool. In this paper, an experimental investigation was conducted to correlate the roughness along the cutting trajectory profile and cutting forces along three different directions: the feed direction (FD), primary cutting direction (CD), and thrust direction (TD), respectively. It was found that the changes of cutting force along CD had a much higher impact on the surface generation than those along FD and TD. Based on the analysis of the spatial power spectral density (PSD), it was found that the surface generation is mostly affected by the tool-work vibration along the cutting trajectory. Cross-correlation of the spatial PSD and force PSD also revealed that when the depth of cut was greater than 5 μm, more similarities were found between these two PSDs. These findings will contribute to the development of online measurement technology of surface roughness in the future.