Abstract: In the process of micro milling, the tool diameter is small and the wear is fast. The tool wear has obvious nonlinear effect on the micro milling force, and the tool run-out has different effects on the wear of per tooth. These factors will lead to the instability and precision of machining process. However, the general micro milling force model considering tool runout and wear effect has not been established, Therefore, the relationship between tool run-out and tool wear per tooth is studied, and a new micro milling force model including tool run-out and tool wear effects is proposed. In this model, the tool run-out and tool wear per tooth are considered in the instantaneous cutting thickness model. According to the force conditions of different cutting edges, the wear variation along the tool diameter direction is associated with the force model coefficient to improve the accuracy of the force model. Finally, through the milling experiments under different milling parameters, the accuracy and effectiveness of the proposed model are demonstrated. The proposed model can be used to detect whether the tool size is within the range of sustainable milling by monitoring the milling force to ensure accuracy and efficiency of micro milling.

Key words: micro milling force, tool run-out, tool diameter wear, cutting thickness