WINDING DENSITY - THEORY AND PRACTICE

Printing paper is one of the chief products of the paper industry worldwide. The paper coming from the paper mill must have certain properties for subsequent printing and converting. As the winding process has a major influence on the paper properties, care must be taken to keep up dimensional stability, existing surface characteristics, a uniform structure of the wound reels and clearly distinctive edge and centre webs. Stress-strain and compression behaviour of the web is crucial to its suitability for printing. Changes in the properties of the paper occuring during the rewind process are detected by measuring the winding density. Measuring this density during the converting process requires an extremely high measuring accuracy, which is difficult to achieve under practical conditions. MisinterpretatiOns with regard to changes in paper properties are often due to errors occuring during winding density measurement. Winding systems permitting an adjustment of the winding density to a wide range of paper properties are best suited to meet printing requirements.