5 Feb. 2024: Valmet is launching two new calender roll covers to extend its roll cover selection. In the new Valmet Calender Roll Covers CL-W and CL-S, the highest wear resistance has been combined with the best load-speed durability and impact resistance. Due to the improvements in material technology, these covers give the longest regrinding intervals under the most difficult calendering conditions in soft and multinip calenders. In addition to graphical papers, they are suitable for specialty papers, as well as container and packaging boards.

“Valmet Calender Roll Cover CL-W provides the best wear resistance, longest running times, excellent barring resistance and high cover surface stability. In the development of CL-W, wear resistance improvement has been the main target. The cover’s exceptionally high wear resistance has been proven both under laboratory and mill conditions. For example, at a mill producing light-weight coated paper (LWC), the roll change interval was increased up to fourfold,” says Tatu Pitkänen, Global Technology Manager, Roll Covers and Maintenance at Valmet.

“Valmet Calender Roll Cover CL-S, in turn, has been developed to improve robustness further and offer the best impact resistance for runs under harsh conditions. It offers a smooth and elastic nip contact. As the impact resistance was the main development target with CL-S, our research and development team combined polymer technology with the latest material additives to improve the elasticity and impact strength in the composite structure. This lowers the risk for sudden cover damages, dents or cover surface marking. Longer lifetime has been proven, for example, at a paper mill that suffered from repeated cover damages due to high nip stresses. The mill is producing supercalendered magazine paper, SC-A,” says Rob Stapels, Global Product Manager, Roll Covers and Maintenance at Valmet.

Significant potential for improving production efficiency and saving costs
Choosing Valmet Calender Roll Cover CL-W or CL-S leads to cost savings due to longer calender roll run times, leading to less roll change and grinding costs. The overall cost is also lower due to the improved cover lifetime. The wear resistant CL-W offers potential for opening barring or shut down interval related production bottlenecks. CL-S can improve product bulk, thus, allowing savings in fiber costs. These allow better time and material efficiency for the production.