Systematic evaluation of calibration methods

Today for geometrically testing and calibrating machine tools, many different measuring devices are used. Generally it is only based on the experience of single employees which methods for calibration are applied. There is no quantifiable understanding of the correlation between measurement method, measurement uncertainty, machine tool build-up (axes arrangement) and quality and the resulting obtainable workpiece accuracy. In this paper a kinematic model of machine tools is used with which resulting deviations of workpieces can be simulated, thus giving a realistic impression of the geometric performance of a machine tool by considering all relevant influence factors. For a 5-axis machining center as an example it is quantified how improved calibration methods can reduce the resulting workpiece deviations significantly. With this knowledge, optimal calibration methods can be chosen and weak points in the machine tool design can be identified systematically. (C) 2008 CIRP.