S-shaped test piece is used to assess the performance of five-axis numerical control machine tools. Compared to traditional test method and test pieces, it performs better and was agreed to be included in the draft international standard at the 79th ISO/TC39SC2 meeting. However, the lack of theoretical research is the barrier to apply for standard and to be widely used. Therefore, this paper aims to study one of the theoretical research that how to choose the suitable tool diameter. We proposed a new research method based on software AdvantEdge, Vector Method for error calculation, Microelement Model of cutting force and deformation model of cantilever beam. The simulation results show that the 20 ≤ diameter < 30 is the proper choices and the 20 is the best choice, which is consistent with the empirical consequence. This method not only provides the theoretical support for the S-shaped test piece, but also can be applied to other parts with complex curved surfaces.

S形试件用于评估五轴数控机床的性能。与传统的测试方法和测试件相比，它的性能更好，并且在第79次ISO / TC39SC2会议上被同意纳入国际标准草案中。然而，缺乏理论研究是申请标准和被广泛使用的障碍。因此，本文旨在研究如何选择合适的刀具直径的理论研究之一。我们提出了一种基于AdvantEdge软件的矢量，误差计算的矢量方法，切削力的微元模型和悬臂梁变形模型的新研究方法。仿真结果表明，直径≤20≤30是正确的选择，直径20则是最佳选择，这与经验结果是一致的。