Calender roll covers
At the calender the paper gets the finishing touch, finalizing it’s quality. The required paper properties are diverse, depending on the paper quality. Paper can be glossy or matt, most often it needs to be smooth, bulk must be saved or the paper needs to be densified, and always the profile should be uniform. Therefor the calender equipment is diverse, from hard nip calender to soft and matt calender, to super and multi-nip calender, and to the belt calender. The paper can be hard and abrasive, or soft and of low strength, and the operating conditions range from low to high load, hot to cool, and low to high speed.
Valmet caters to all these positions and requirements with an extensive range of hard and soft covers. A typical calender cover is a composite cover, and Valmet offers composite covers of different performance at economic, standard, and premium level. The right choice of cover ensures special performance such as e.g. barring resistance. For special bulk-saving calendering there is the durable polyurethane cover, while for extreme smoothness and long-lasting running there is the hard coating.
Valmet calender roll covers are renowned for their long grinding intervals and smooth surface quality, which means longer service intervals and optimum paper or board properties. Besides providing better marking resistance, our calender covers allow much higher speeds and temperatures without damage than conventional alternatives. For paper and boardmakers these factors mean quality. Let Valmet help you to run with the most suitable cover for your calender.
- Smooth surface for excellent paper quality
- Wear and barring resistance for long grinding intervals and ease of maintenance
- Durability for a long lifetime
Click the image above to use Valmet’s roll cover application tool to find the right covers for your calender applications
Articles and references
Valmet's selection of calender roll covers: The result of extensive know-how
Not many roll cover manufacturers can offer as wide a range of calender covers as Valmet can today. Most attention often goes to highperformance covers addressing difficult conditions in the calender, such as vibration and barring in high-speed on-line calenders. But there are also many calenders that run with no vibration issues, and when such “antibarring” covers are not needed, other properties become more important.
Effect of composite roll cover hardness on calendering
Every now and then the question arises of whether paper producers can improve end product quality by using softer composite covers in the calender section when dealing with bulky grade calendering, such as wood-free or liquid packaging board grades.
Valmet Calender Roll Cover CL – double the run time with Valmet’s new calender roll cover
The high-end calender roll cover CalLeopard has achieved promising results, with mills reporting extended running times and trouble-free maintenance. The new composite cover is uniquely designed to meet the tough calendering requirements.
Valmet Calender Roll Cover CJ improves calendering result
Valmet Calender Roll Cover CJ is directed specifically at coated paper grades. It’s modern manufacturing and materials technology targets simultaneously both paper quality and cover durability.