Critical geometric errors identification of a five-axis machine tool based on global quantitative sensitivity analysis

Rotation axes have been proven to be the greatest factor leading to machine tool errors, which seriously affect the machining accuracy. Therefore, it is imperative to identify the geometric errors of the rotation axes. This research focuses on how to identify the critical geometric errors of the rotation axes, so that the coupling effect of geometric errors which seriously affects the identification of geometric errors of the rotation axes can be examined. To achieve this goal, this paper proposes a global quantitative sensitivity analysis method based on homogeneous transformation matrix (HTM) theory and Sobol sensitivity analysis method. The size and randomness of geometric errors are taken into consideration and the specific indexing angles of the rotation axes are introduced to identify the critical geometric errors of the five-axis machine tool. Based on this analysis method, each geometric error components and the coupling effect between different error sources are evaluated under different indexing angles. The variation of the coupling effect of each error components within the traverse of the rotation axes is explored. The geometric error measurement experiment is established and the results are compared with the simulation results. The simulation results and experimental results reveal that the critical geometric errors that affect the machining accuracy and the variation of the geometric errors coupling effect, which provides useful guidance for the manufacturers and users of five-axis machine tools.