Mapping the effects of positioning errors on the volumetric accuracy of five-axis CNC machine tools

Fixe-axis capabilities on machine tools are becoming increasingly common. However, the problem of modeling the propagation of errors of individual axes through the kinematic chain, and their effect on the position and orientation errors of the cutting tool in the machine's work space has not been addressed. To increase the accuracy capabilities of such machines it is crucial to be able to study this propagation and develop approaches to minimize their effects on the errors at the tool tip. This paper discusses an approach to model the effects of the positioning errors of a machine's axes on the accuracy (positioning and orientation) of the cutting tool in its work space. Computer programs are developed for implementing the models and generating error contours or maps showing the variation of the different components of a machine's volumetric errors in its work space. This is a useful tool that can be used in machine tool design for the budgeting of errors and for optimization of a machine's accuracy.