Using Wound Roll Density Analysis for Supercalenders, 1990 Finishing and Converting Conference Proceedings

Actual paper mill studies show the benefits of wound roll density (WRD) analyses. Evaluating wound roll density in the radial (machine) direction is a common way to inspect the quality of rolls from winders. Likewise, WRD analysis can be valuable for other web handling processes including supercalendering. The WRD analyzer estimates the wound-in caliper of the last series of wraps of paper applied on the roll. Thus, WRD relates to wound-in tension, wound-in caliper, and roll hardness.

Poorly wound rolls can produce defects such as buckles and telescoped rolls. Better winding based on WRD can improve the reel windup as well as the consistency of surface quality. Changes in speed, nip pressure or temperature can change densification of the web and paper roll.

Several control factors influence the WRD profile of a roll or log of paper. Automatic controls include calibration settings for ratio of centerwind and surface drum winding and tapered tension. Manual controls include secondary arm pressure, web tension setting, and settings for ratio of centerwind and surface drum winding.