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Ultra-precision cutting (UPC) technology can directly achieve freeform surfaces with form accuracy in sub-micrometer and surface finishing in nanometer, and the achieved surface quality affects the functionalities of the components. Different from the conventional machining process, the effects of workpiece material properties on surface generation in UPC are ignorable. The influences of plastic side flow and elastic recovery are very important for the surface quality in UPC, while few studies were found to evaluate the extent of the two phenomena. This paper makes theoretical and experimental studies on the factors affecting the side flow and recovery and proposed a method to characterize the extent of plastic side flow and recovery by studying the deviation of the groove radius in single ruling. Experiments are conducted to machine grooves with different cutting parameters on different workpiece materials. The experiment results agree well with the theoretical analyses and show that under the combined effect of side flow and recovery, the generated groove radius may be larger or smaller than the theoretical one. Moreover, the proposed method makes effective evaluation on extend of swelling and recovery in UPC.

This paper studies the effect of cutting strategy on surface generation in ultra-precision raster milling (UPRM). By adding the influences of shift length and tool-interference on surface generation, a holistic surface roughness prediction model is built which takes into account the effect of cutting parameters, tool path generation, geometry parameters of diamond tool, the size of the workpiece and machine characteristics. The optimal shift ratio can be achieved by changing factors involved in developing cutting strategy to improve surface quality without decreasing machining efficiency. Conditions for the presence of tool-interference in UPRM are presented. Based on the holistic surface generation model, an integrated system is developed to automatically generate the numerical control (NC) program, and predict surface quality and machining efficiency. A series of cutting experiments has been conducted to verify the proposed surface generation model and test the performance of the integrated system. The experimental results agree well with the predicted results from the model and the integrated system.

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