Polyurethane Roll Covers Improve Tissue Quality
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Metso has launched polyurethane roll covers for tissue machine press and suction press rolls. The new PressHusky and VacuHusky roll covers are designed especially for yankee press applications widely used in dry crepe tissue production. As an option, a Metso iRoll online nip profile measuring system can be applied with these new roll covers.
Some tissue grades are sensitive when it comes to bulkiness and thickness, so lower nip pressures are preferred in pressing. Traditionally, this has been a limitation in the use of polyurethane roll covers in yankee press applications, according to Metso. However, the new polyurethane material of PressHusky and VacuHusky covers offers several hardness alternatives and more options for cover topography, which results in maximized dewatering and the desired tissue quality with high bulkiness and thickness.
PressHusky and VacuHusky covers also provide lowered operating costs due to the reduced need for regrinding, the company notes, adding that their low rolling resistance creates energy savings thanks to reduced roll drive power. In addition, solid press rolls with a PressHusky cover can be operated cost-efficiently without internal water cooling.
Nip profile monitoring and control has been quite a challenge in a nip formed between a roll and a yankee dryer, Metso continues. Reliable information on nip profile errors or skewness problems can only be gained when measurements are taken at operating speed with the desired steam pressure inside the yankee dryer. Metso's iRoll measurement technology can be utilized with these new polyurethane roll covers, providing accurate nip pressure profile data for efficient nip control.
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