Thermal issues in 5-axis machine tools

This paper describes research carried out with the Mori Seiki NMV 5000 DCG machine tool at IWF / ETH in Zurich in the field of precision of rotary axes influenced by thermal effects. Presented are an extended physical compensation model, the thermal behavior of the NVM 5000 DCG under the influence of cutting lubricant, and the evaluation of the thermal behavior using an especially designed test piece. A physical model, which computes the thermal location errors and the table diameter error ER0T of the machine tools rotary axes, is extended by a cooling model. The cooling model computes the inlet temperature of the internal cooling system based on the power input to the drives. The thermal test piece allows evaluating a combination of thermal errors of the rotary and swiveling axis and the main spindle. For evaluation of the thermal test piece a Coordinate Measuring Machine (CMM) can be used and no additional machine tool measuring equipment is necessary. The comparison of measurements with and without cutting lubricant shows that the inlet temperature of the cutting lubricant has a significant influence on the overall thermal behavior of the machine tool.