Measuring physical properties of paper with an on-line visual sensor

Experimental results of a novel on-line paper shrinkage sensor are presented, showing a clear correlation with laboratory test indices such as elongation, breaking load and tensile energy absorption. Trials carried out in a paper machine producing sack paper also include a dynamic analysis of the effect of jet-to-wire ratio on paper shrinkage based on these measurements. The measurement is based on digital image processing techniques and provides a tool for instantaneous corrective control of physical variables during paper manufacture.