The Far-field laser diffraction is proposed for measuring tool cutting-edges geometry with sub-micrometer precision. In particular, by eliciting an optical diffraction phenomenon, the cutting-edge of the tool can be monitored without a diffraction limit. This method can also be applied for on-machine measurements because of the simplicity and long working distance of the optical system; high precision can be achieved by using a laser light and there is no need for a vacuum environment. In this study, an on-machine tool measurement device using laser diffraction was developed to experimentally measure tool displacements of order of hundreds of nanometers; a piezo-drive stage was also used. Measurements of the cutting-edge curve of a ball endmill and a tool cutting-edge tolerance were also experimentally monitored.

1. [1] T. Pfeifer and L. Wiegers, “Reliable tool wear monitoring by optimized image and illumination control in machine vision,” Measurement, Vol.28, pp. 209-218, 2000.
2. [2] H. S. Lim, S. M. Son, Y. S. Wong, and M. Rhaman, “Development and evaluation of an on-machine optical measurement device,” Int. J. of Machine Tools & Manufacture, Vol.47, pp. 1556-1562, 2007.
3. [3] H. H. Shahabi and M.M. Ratnam, “On-line monitoring of tool wear in turning operation in the presence of tool misalighnment,” Int. J. Adv. Manuf. Technol., Vol.38, pp. 718-727, 2008.
4. [4] P. Khajornrungruang et al., “On-Machine Cutting Edge Profile Measurement for Micro Milling Tool,” Trans. of the Japan Society of Mechanical Engineers, Series C, Vol.70, pp. 3556-3563, 2004.
5. [5] E. Hecht, Optics 4th (Ed.), Addison Wesley, 2001.