Axis Location Errors and Error Motions Calibration for a Five-axis Machine Tool Using the SAMBA Method

Abstract

Positioning accuracy is one of the most important factors influencing a machine tool's ability to manufacture parts meeting the required tolerances. Thus, regular check-ups followed by geometric compensation or mechanical adjustments are necessary to prevent accuracy degradation on such machines. This paper presents an enhanced measurement strategy to extend the capability of the Scale and Master Balls Artefact (SAMBA) method to the estimation of not only the axis location errors but also error motion parameters modeled as ordinary polynomials. This indirect measuring method uses on-machine probing of a scale enriched uncalibrated master balls artefact to gather observations of the machine volumetric behaviour. The analysis of the kinematic model and its associated Jacobian matrix which characterizes the sensitivity of the volumetric errors, as detected by the SAMBA method, to the axis location errors and error motions provide the mathematical basis for the probing strategy design. The simulation and experimental results presented demonstrate the contribution of the applied strategy in enriching substantially the machine tool error model.