On-machine volumetric-error measurement and compensation methods for micro machine tools

• Published in: International journal of precision engineering and manufacturing Vol. 14; no. 6; pp. 989 - 994
• Main Authors: Wang, Shih-Ming, Lin, Ji-Jun
• Format: Journal Article
• Language: English
• Published: Springer Korean Society for Precision Engineering 01.06.2013
• Subjects: Engineering; Industrial and Production Engineering; Materials Science; On-machine Measurement; Volumetric error; Micro machine tool; Error compensation
• ISSN: 2234-7593; 2005-4602
• DOI: 10.1007/s12541-013-0131-x

The CNC micro machine tool is an essential of the micro machining process for manufacturing miniature high-tech products. A software-based error compensation method based on measured volumetric errors that can pre-compensate cutting path can further enhance a machine’s accuracy without increasing its manufacturing cost. Considering the limited workspace of a micro machine tool and the instrument cost, an on-machine and vision-based measurement method integrating machine vision method with use of 3 COMs and homogeneous transformation method was proposed in this study. Sensitivity analysis was conducted to analyze the influence of the CMOS pixel error to the measurement accuracy. To improve the machining accuracy, the measured errors were directly compensated to the machining trajectory with use of an error compensation method that consists of an element-free error interpolation scheme and a recursive software error compensation scheme. Experiments on a toggle-type micro machine tool were conducted to verify the effectiveness of the proposed methods. The results have shown that the feasibility and effectiveness of the proposed methods. The tracking errors of the machine was further improved from (x = 7.9 μm, y = 4.1 μm) to (x = 5 μm, y = 3.7 μm).