The film sizing and film coating process have a direct impact on paper and board quality, both on paper strength as well as on paper appearance. Moreover, as on-line processes they are critical for the paper machine line efficiency. This puts high demands on the sizer roll covers.
For sizing, pigmenting and coating Valmet offers a wide range of soft and hard rubber and polyurethane covers, as well as hard composite covers and ceramic coatings.
The Valmet sizer roll covers are suited for all types of sizers such as film sizers, spray sizers, pond sizers and GRSPs. Valmet sizer roll covers produce excellent paper quality due to the uniform coat weight and film profiles reducing skipping, splashing or misting. Long roll cover running time makes production cost-efficient and of low maintenance.
Valmet Sizer Roll Cover SH-W and Valmet Sizer Roll Cover CF have been developed from special rubber and polyurethane materials that contribute to a trouble-free sizing process. They are high performing covers with wear resistant for maintaining both CD profile and surface roughness, for long running times with high stable film amount. The long lists of deliveries confirms the excellence of these covers.
And we continuously strife to improve on our performance, the recently introduced composite cover for pond and spray sizers offers increased running time compared to hard rubber covers, while being more affordable than hard coating.
Quality defects due to CD profile issues, e.g. variation of coat weight profile, result in lower material efficiency and higher costs per ton. New opportunities to improve board and paper quality are created with better profiling of coating and sizing through the simultaneous measurement of the roll nip and applicator rod profile online. The full benefits of iRoll Sizer are available with Valmet polyurethane roll covers.
Valmet is the market leader in ﬁlm coaters and sizers, and has developed a great deal of related process know-how. We have put this expertise to good use in developing new roll cover materials that deliver uncompromised sizing and coating performance with both grooved and smooth rods, as well as with coating blades.
Sizing adds value to the paper quality by enhancing its properties. Sizing paper with starch can increase both the surface strength of the paper, as well as the bulk strength. Sizing or pigmenting can also be applied with PVA or silicone which transforms the base paper into release paper. Additionally, sizing can be used to densify and seal the paper surface, thus reducing the absorption, for instance, from the coating process.