Theoretical study on frequency spectrum characteristics of surface profiles generated in micro-end-milling process

Micro-milling is a flexible and promising fabrication process. Based on the analysis of the surface formation process in micro-end milling, the theoretical surface model was established to investigate the influence of seven identified factors, i.e., minimum cut thickness (MCT), elastic recovery, plastic side flow, radial and axial runout, tool wear (corner radius and unbalanced wear coefficient), and vibration on the frequency spectrum characteristics. The increase of MCT coefficient and plastic side flow height could increase the amplitude of the sft and 2sft frequency, while the scenario for the elastic recovery coefficient witnessed a reverse trend. The amplitude of the 0.5sft frequency decreased with the increase of the radial runout offset, while the amplitude of sft frequency increased as the radial runout offset increased; the scenario for the influence of the radial runout angle was opposite. The increase of the axial runout offset could lead to the increase of the amplitude of both 0.5sft and sft frequency. The increase of corner radius could lead to a slight reduction of the amplitude of the 0.5sft and sft frequency. The occurrence of the vibration with high frequency leaded to a low spatial frequency. The corresponding tool wear experiment was conducted, and the frequency-spectrum characteristics of the micro-milled surface were compared with the simulated results to validate the established profile models. The paper successfully correlated the relative importance of the identified individual factors to the corresponding frequency spectrum characteristics, and it had potential applications in predicting and controlling the spatial content of machined surfaces.