Advanced Techniques for Surface Smoothness Measurement and Control, 1996 Finishing and Converting Conference Proceedings

Lee Chase, John Goss and Edward Belotserkovsky

Measurex Corporation

A brief history of traditional surface smoothness measurement and the physics behind them, leads into the discussion of a new approach which can now be applied to on machine applications. An on-line sensor has been developed to provide surface properties measurements on printing grades of paper, linerboard, and tissue. The sensor uses laser triangulation to measure surface contours. The small measurement spot size (20 microns) and fast response of the sensor (1 Mhz) allows us to resolve scale sizes of less than 40 microns diameter on a sheet moving up to 1200 M/min. the sensor measures, to high precision (-0.1 micron), the variation of the surface height from the mean. Further, the scale size over which the variations occur is measured. The RMS surface height variations in microns is measured for each scale size region. Results from field trials on light and medium weight coated, linerboard, coated thermal FAX, and tissue are presented. The sensor has shown a good correlation with traditional air leak smoothness measurements.