Distribution Pattern
The variation in water content across the width of a paper web as it is wound onto the reel at the end of the paper machine defines the uniformity of the production run. This reel moisture profile is a critical quality parameter that affects the flatness and the conversion performance of the board. An uneven distribution leads to defects like baggy edges, ridges, cockles and moisture streaks.
Control System
Scanning sensors move back and forth across the moving web to measure the moisture and send feedback to the drying sections. The reel moisture profile is managed by adjusting the steam pressure in the drying cylinders or using water spray dampers to add moisture to dry spots.
Downstream Effects
Printers and converters require a consistent moisture level to ensure that the paper remains stable during high speed processing. If the reel moisture profile is inconsistent, the board will develop internal stresses that cause it to curl or twist once the rolls are slit into sheets. This leads to misregistration on the press and jams in the packaging machinery.
Maintaining a flat profile is essential for achieving high quality graphics and efficient production. Automated control systems have greatly improved the precision of this profile in modern mills.
