Dryer section roll covers and coatings help to keep rolls and cylinders clean and protect surfaces from wear and corrosion in hot and humid environments. Choosing the right roll cover ensures good dryer runnability and allows savings in dryer fabric usage and doctoring.
Valmet’s selection of roll covers includes thermally sprayed metallic coatings for rolls and cylinders, and thicker polymeric covers for paper and fabric guide rolls. The product portfolio also provides solutions for more specialized tasks, such as electrically conductive covers for lead rolls in positions where static electricity is an issue.
Especially in the case of dryer cylinders, non-stick surface features combined with good doctorability provide uniquely desirable features for cylinders, allowing users to enjoy clean surfaces and problem-free operation. Cylinder coatings can be manufactured during shutdowns inside paper machines. With Valmet roll covers, dryers can be operated safely, efficiently and with high reliability.
Valmet Lead Roll Cover GO-R is a unique non-stick coating solution for non-doctored dryer fabric lead rolls. For rolls that are exposed to contaminants, Valmet Lead Roll Cover GO-R combines wear resistance and non-stick properties, ensuring excellent roll cleanliness without doctoring.
Runnability problems, sheet picking, and dusting caused by poor dryer cylinder release are challenges troubling many paper mills. Dirty dryer cylinder surfaces that reduce drying capacity and lead to sheet moisture profile deviations are also often encountered. The solution to problems like these is Valmet's Dryer Roll Cover DOH release coating for doctored drying and cooling cylinders.
The highlight of this new coating is its release layer, made of a unique fluoropolymer exclusive to Valmet. It has been optimized for excellent release and doctoring properties, as well as stable operation due to its good resistance to wear and flaking.
Valmet Dryer Roll Cover DOH coating keeps cylinder surfaces clean and provides excellent release and doctoring properties. It is ideal for on-site coating. According to Mikko Vaulamaa, Dryer Roll Cover DOH stays cleaner than other release coatings, and there are no spots where dirt builds up.