Abstract:In view of the influence of tool setting position on the accuracy of a machine tool and the evaluation of its final accuracy and performance, a method of geometric accuracy prediction for a five axis CNC machine tool (FACMT) considering tool setting position is proposed. Firstly, the kinematics equation of the FACMT based on a NAS979 inclined cone frustum is established by using multi-body system theory. On this basis, the solving equations for the actual machining position and NC machining instructions of the test piece based on tool setting position are built, the prediction model of geometric accuracy for the FACMT is established and the accuracy indexes such as roundness, angularity and concentricity of the cone frustum are predicted. Then, the simulation prediction for accuracy of the FACMT is carried out. The predicted values of roundness, angularity and concentricity are 0.0251 mm, $\phi $0.057 3 mm and 0.019 2 mm, respectively, while their required standard tolerances are 0.100 mm, $\phi $0.100 mm and 0.030 mm, respectively. The simulation results show that the predicted accuracy indexes of the cone frustum can meet the requirements of standard tolerance accuracy. Finally, in order to verify the effectiveness of the method, the cutting experiment of the test piece of inclined cone frustum is carried out. The maximum values of roundness, angularity and concentricity are 0.038 0 mm, $\phi $0.093 1 mm and 0.028 2 mm, respectively, the minimum values are 0.031 6 mm, $\phi $0.065 8 mm and 0.024 6 mm, respectively, and the measured mean values are 0.035 6 mm, $\phi $0.080 5 mm and 0.027 1 mm, respectively. The experimental results show that the measured mean values are in good agreement with the predicted ones. Therefore, in the process of precision inspection and acceptance of newly developed machine tools, this method can be used to evaluate their accuracy and performance accurately, quickly and intuitively.