Coating and sizing applications require a relative soft cover (50 to 120 P & J) with strength and toughness to withstand wad impact. Variokote rubber compound has been the backbone of coater and coater backing roll covers. Supercoat has advanced coater cover durability with increased durability.

Now Flexcoat extends the abrasion and impact resistance to new levels that deliver previously unattainable performance and service life.

Coater Backing Rolls
The coater roll applies the coating chemicals to the surface of the sheet for a uniform and consistent coating.

The coater roll cover must have superior marking and crack resistance to withstand wad impact and sheet wraps, while maintaining superior wear resistance to provide long runs and the ability for the paper maker to deckle-in and deckle-out without sanding the cover ends.

High Speed Rod or Blade Metering Size Press Rolls
Rods or blades meter size onto two soft rolls, one about half the P&J hardness as the other, which form a pressure nip and carry a uniform film of size into the pressure zone for transfer to the sheet.

The size press covers in this type of size press must have excellent abrasion and chemical resistance, and temperature and hardness stability to ensure optimum sizing and long runs between regrinds, while maintaining a suitable surface to uniformly release the sheet and prevent film splitting. The cover needs to hold the appropriate amount of starch/coating and readily transfer it to the sheet.

Conventional Hard Size Press Roll
Size press rolls in pond size presses operate in pairs, one hard and one soft, to provide the proper pressure for efficient application of the sizing to the sheet and to reduce sheet stealing.

The hard size press cover must maintain its hardness and crown profile up through 250 degrees F to provide consistent nip intensity and to prevent non-uniform abrading of the soft cover. It must also maintain the proper surface finish for optimum sheet transfer/release and to prevent film splitting.

Conventional Soft Size Press Roll
Size press rolls in pond size presses operate in pairs, one hard and one soft, to provide the proper pressure for efficient application of the sizing to the sheet.

The soft size press cover must have excellent abrasion and chemical resistance, and temperature and hardness stability to ensure optimum sizing and long runs between regrinds, while maintaining a suitable surface to uniformly release the sheet and prevent film splitting.

Gate Roll Size Press / Coater Rolls
Gate roll size presses and coaters come with various different configurations, number of rolls and terminology. In general, though, they each follow the same principle. There is a series of rolls on each side of the sheet. A pond is formed in the nip of the outside two rolls, typically called the gate roll and metering or distributor roll. These rolls are run at different speeds to control the amount of size or coating applied to the sheet. The size or coating is then transferred either directly or through a series of transfer rolls to the applicator roll where it is then applied to the sheet.

The gate rolls are rubber covered ranging from 20 to 180 P&J. The distributor roll or metering roll covers range from hard rubber, composite, ceramic or chrome to soft rubber. The applicator roll covers will be rubber or polyurethane ranging from 20 to 70 P&J.

Spreader Rolls
The web is subject to flutes, creases and wrinkles, particularly in coating and sizing applications. To enable a flat web and even paper qualities, the web needs to be spread in cross direction. Stowe Woodward produces bowed spreader rolls in a special design for moisture applications with steel or rubber surfaces, or FlyBow, an end-to-end design made from composite compound materials (like carbon fibers).

Other Products and Services
Stowe Woodward Application and Service Engineers are equipped with special optimization tools and expertise that increases the effectiveness of any coating / sizing section.

The latest technology combined with years of experience deliver nip-profiling, crown calculating, cover selection and mechanical services to ensure superior performance in coating and sizing.