Abstract: The relative tool-work vibration is one of the dominating factors in forming nano-scale surface, which is generally studied by using spectrum analysis method, direct measuring approach and cutting force method. However, all of them cannot be used to predict surface roughness and cannot gain the true vibration information in cutting process simultaneously, which impacts the prediction accuracy of surface roughness. In order to solve the issues, a new method of extracting and measuring relative tool-work vibration in single point diamond turning is presented through extracting data from machined surface and defining equivalent amplitude to analyze how the vibration is influenced. The analysis results indicate that the relative tool-work vibration is mainly influenced by spindle speed and material characteristic. Furthermore, the relative vibration in machining an inhomogeneous material, which depends on the relationship between the trapped phase and contact size of the tool, is larger than the homogeneous materials, Finally, the extracted vibration is used to predict surface roughness. Higher prediction accuracy shows the vibration extracted by this method is closer to the true vibration in cutting than other methods.

Key words: Equivalent amplitude, Relative tool-work vibration, Single-point diamond turning, Surface roughness