A systemic approach to identify the volumetric and dynamic errors for five-axis machine tools with double ball-bar test

Volumetric error and dynamic error are the main error sources that lead to position deviation of the cutting tool relative to the workpiece in five-axis machine tools. To comprehensively evaluate the positioning performance of the five-axis machine tools, this paper presents a comprehensive approach to identify both the volumetric and dynamic errors. A group of circular trajectories for a double ball-bar device is designed and performed in the measurement procedure. The volumetric performance is firstly evaluated by calculating the shape deviation between the real and designed circular trajectories. Since geometric errors are the main error source of volumetric inaccuracy, a position-independent geometric error (also named as location error) is identified from the measurement data in this work. A least square method–based algorithm is formulated to calculate the squareness errors between the three linear axes and the location errors of the two rotary axes. To evaluate the dynamic performance, the tangential and normal deviations between the real and designed circular trajectories are monitored. Particularly, as the magnitude of dynamic error has a strong correlation with the feedrate, the circular tests are repeated at three different feedrates. The experimental study is conducted on a five-axis machine tool to validate the effectiveness of the proposed method.