Evaluation of machine-tool motion accuracy using a CNC machining center in micro-milling processes

Abstract

The demand for micro holes, micro-molds, and micro forms continues to grow as high-tech industries demand miniaturized products. Sectors such as aerospace, microelectronics, medicine, and even the automotive sector, are just some examples of enterprises that are taking advantage of micro-manufacturing technologies. Within this framework, the need to adapt the knowledge of macro-scale manufacturing processes to micro-scale is evident. This paper provides the insight needed to improve milling as a micro-manufacturing process. The goal is to characterize motion system to reduce error and improve accuracy with different process parameters on final shape for micro-parts while standard milling machine with linear motor and servomotor is used. Geometrical error and accuracy caused by motion control and control software error sources is evaluated and analyzed. Results will help decision on process parameters and it verifies that standard milling machine is useful to produce micro-parts. The work is carried out by theoretical principles and experimental work, the machine-tool motion accuracy of a medium machining center specializing in the micro-milling of elliptical cavities on aluminum workpieces. Measurements were taken to evaluate deviations and/or errors in geometric accuracy and the geometric quality errors caused by motion control and control software. The results show that due to the structure and inertia of the machine tool, acceleration and deceleration do indeed affect the accuracy and quality of the micro-part. Furthermore, errors from motion control and/or control software are present because differences in the moving carriages create instabilities

The authors would like to express their gratitude to the Product, Process and Production Engineering Research Group from the University of Girona for the facilities provided during the experiments and for all their valuable support. This work was partially carried out with the support of the grant from the European Commission project IREBID (FP7- PEOPLE-2009-IRSES-247476)