A Noncontacting Method for Measuring Paper Sheet Grammage and Thickness Using Acoustic Tone Bursts
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Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.
This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.
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Abstract
The grammage, ie., mass per unit area, is one of the most important quality factors in paper industry. The grammage of the paper web is constantly monitored during the paper manufacturing, and the ever rising pulling speeds and wider reels demand more accurate and faster methods to monitor the grammage changes in both the cross direction and in the machine direction. Nowadays, the standard method is to use radioactive beta rays, which method was invented in 1950s. The beta radiation is attenuated as a function of sample grammage, but the temperature of surrounding air, and the atomic number of the sample also affect the measured intensity of the beta rays. These effects can be conquered by calibration and by monitoring the temperature. But one technical difficulty remains, though. Only one measuring head is traversing across the paper web, which is quite a slow method to achieve the cross profile of the paper web [1–2].