Novel in-situ methodology for geometric error characterisation of rotary axis errors on multi-axis machine tool.

Complex mechanical parts with high geometry and dimensional accuracy require multi-axis machining with low volumetric errors. To achieve such precision in the micrometer range, the geometric errors of the machine tool must be correctly identified and compensated. This article proposes a new methodology to measure directly the geometric errors of the rotary axes on machine tool. The methodology consists of a system of several non-contact sensors that are strategically placed around a datum cylinder. This system is held on the machine spindle and remains static over the entire measurement. The relative motion between the sensors and the cylinder is obtained by rotating the table of the multi-axis machine tool. The cylinder could be fast centered and leveled by using micro linear stages. A rotation stage enables to decouple the rotary axis motion from the datum cylinder rotation, consequently carry out methodologies of errors separation associated with multiprobe and multistep methods.