High precision grey-box model for compensation of thermal errors on five-axis machines

Thermally induced errors of machine tools cause up to 75% of the geometric errors on workpieces. Research carried out in the last decades focused on influences by the environment, spindles and linear axes. With the increasing demand for five-axis machining, the rotary/swivelling axis units have to be checked and compensated for thermal errors. The R-test set-up is a proper measuring device to characterise these errors. This paper introduces a compensation approach to reduce up to 85% of the thermally induced location errors of rotary/swivelling axis units based on internal NC signals, like power supplied to drives.