A Fiducial-Aided Reconfigurable Artefact for the Estimation of Volumetric Errors of Multi-Axis Ultra-Precision Machine Tools

In this paper, a fiducial-aided reconfigurable artefact is presented for estimating volumetric errors of multi-axis machine tools. The artefact makes use of an adjustable number of standard balls as fiducials to build a 3D artefact which has been calibrated on a coordinate measuring machine (CMM). This 3D artefact demonstrates its reconfigurability in its number of fiducials and their locations according to the characteristics of workpieces and machine tools. The developed kinematics of the machine tool were employed to identify the volumetric errors occupied by the workpiece in the working space by comparing the information acquired by on-machine metrology with that acquired by the CMM. Experimental studies are conducted on a five-axis ultra-precision machine tool. A developed 3D artefact composed of five standard spheres is measured by the integrated on-machine measurement system. Factors including the gravity effect and measurement repeatability are also examined in order to optimize the geometry of the artefact. The results show that the developed 3D artefact is able to provide information about the working space occupied by the workpiece.