A new compensation method that enables not only to improve the geometric accuracy of a machining center but also to improve the workpiece accuracy has been developed. The strategy of our evaluation and compensation method utilize coordinates measuring machine (CMM) as a master gauge because of its accuracy so that machine operator devote himself to machining and estimator of accuracy dedicate in measurement. As each operator knows the characteristics of machining center and/or CMM, the results obtained are enough reliable to evaluate the accuracy of both machining center and workpiece. The geometric error is evaluated from results of both the profile and position of boring centers with the workpiece prescribed in JIS B 6336-7-A320. The measured data contain not only geometric error results from mother machine but also various errors such as thermal elongation, tool deformation, transient machine displacement by hydraulic lubrication and so on. In our study, these errors except the geometric accuracy of a machining center are neglected by setting the cutting condition not to affect the desired machined workpiece previously. The total pitch error and geometric error are predicted by using the transform formula including error parameters measured by CMM. The predicted results are enough accurate to compensate geometrical error and position error as the inverse problem. In this report, the effects of predicted results and compensated results are shown with the experimental procedure.
