Systematic Machine Tool Error Identification and Compensation Through Test Part

Abstract The enhancement of machine tool accuracy has a direct effect on part quality. The state-of-the-art technology for this is the compensation method based on the measurement of the machine tool error parameters. This technology, however, has two major drawbacks: (i) it requires long calibration time (ii) for many applications this complicated compensation process is over specified because the parts have limited features and dimensions, and hence the compensation of whole working space is not needed. Furthermore, if the compensation of machining systems for high-volume production is considered, then the fast error measurement and subsequent rapid compensation becomes critical, and the current technology obviously cannot meet these requirements. An alternative method that we propose in this paper is to measure the part rather than the machine, and compensate the machine tools according to these measurements. This proposed methodology requires the modeling of the relationship between the machine tool errors and the part errors, which is called here “machine-part error mapping model”. The modeling enables to identify the individual machine tool error parameters that contribute on the part error. In order to use this model to compensate for the machine tool error, test part should be carefully developed. In this paper, several rules in the design of test part are presented first, and as an example, the test part for the flatness error compensation of horizontal machining center was designed. From the measurement result of the machined test part, each error source parameters that are responsible for the chosen machining process were identified, and compensated by using the real time compensation system.