Some Optical Methods of Characterizing Solid and Particulate Materials During Manufacturing Processes
Non destructive Testing is usually seen as an end-of-process quality control step. It is becoming apparent however that inspection should be carried out as early as possible in the process. In this paper two methods of non-invasive measurement using lasers will be described. Since they are non-invasive these measurements can be made on hot or fast moving materials and hence at an early stage in some manufacturing processes.
The first method is generation and detection of ultrasound in solids. This can be used for measuring grain scattering and attenuation of ultrasound using lasers of moderate power. Applications include measurement of grain size in metals during rolling operations and monitoring during welding.
The second method is optical sizing of particles or droplets in a gas stream. Instrumentation has been refined so that a wide range of particle sizes and types can be measured. Applications to powder metallurgy, plasma spraying, spray drying and paint spraying will be described. In the last example the philosophy of this sort of measurement is discussed. In application to paint spray quality control it was found that the economical solution in practice is to develop an accurate model using the optical measurements for validation and use the model, with cheaper on-line measurements, for process control.
KeywordsLaser Doppler Anemometry Ultrasonic Attenuation Quality Control Step Spray Booth Paint Finish
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- 1.W.N. Reynolds and R.L. Smith, Brit. J. NDT Sept, 291 (1985).Google Scholar
- 2.K. Goebbels, Res. Tech. NDT Vol. IV. ed. R.S. Sharpe, (Academic Press, London) (1982).Google Scholar
- 3.C.B. Scruby, R.J. Dewhurst, D.A. Hutchins, S.B. Palmer, Res. Tech. in NDT, Vol. V ed. R.S. Sharpe (Academic Press, London) (1982).Google Scholar
- 4.W. Kaule, 8th World Conf. NDT Cannes, 1–7 (1978).Google Scholar
- 5.C.B. Scruby, R.L. Smith, B.C. Moss, Int. J. NDT (to be published).Google Scholar
- 6.L.E. Drain, “The Laser Doppler Technique” (Wiley) (1981).Google Scholar
- 7.N.P. Smith, J.O.W. Norris, D.J. Hemsley, M.L. Yeoman, Third International Conference on Liquid Atomization and Spray Systems, London (1985).Google Scholar
- 8.I. Filkova, P. Cedik, Proc. 3rd Int. Drying Symp., U. B’ham (1982).Google Scholar
- 9.T.C. Patton, “Paint Flow and Pigment Dispersion”, Wiley N.Y. 2nd Ed. (1978).Google Scholar
- 10.H.E. Huppert, Nature 300 p427 (1982).Google Scholar