A sizing roll is a specialized roll installed in the size press section of a paper machine. It works as part of a roll pair that applies sizing solution, usually starch-based chemicals, onto both sides of the paper web as it passes through the nip.
In modern papermaking, surface treatment is an essential process for improving paper strength, printability, appearance, and functional performance. One of the most important components in this process is the Sizing Roll, which plays a key role in the size press section by ensuring accurate and uniform application of sizing chemicals onto the paper web.
The sizing process allows paper manufacturers to improve properties such as surface strength, water resistance, stiffness, and printing performance. The quality and precision of the sizing roll directly influence coating uniformity, chemical penetration, paper appearance, and overall production efficiency.
The roll surface is normally covered with a specially selected rubber or polyurethane material to provide the required flexibility, chemical resistance, and surface performance. During operation, the two sizing rolls create controlled pressure to ensure even liquid transfer and consistent paper treatment.
Printing paper production
Writing paper manufacturing
Packaging paper production
Specialty paper applications
1.Uniform Application of Sizing Solution
The primary function of the sizing roll is to ensure that the sizing liquid is applied evenly across the entire paper width. Uniform application is essential for maintaining consistent paper properties and avoiding quality variations.
2.Improving Paper Strength
Surface sizing improves the bonding ability of paper fibers, increasing surface strength and reducing problems such as fiber picking during printing or converting processes.
3.Enhancing Printability
A properly sized paper surface provides better ink absorption control, improved smoothness, and enhanced printing quality. This is especially important for high-quality printing papers.
4.Improving Water Resistance and Surface Performance
Sizing treatment helps control liquid penetration and improves resistance to moisture, making the paper more suitable for demanding applications.
5.Supporting Stable Production
A precision sizing roll maintains consistent nip pressure and chemical transfer, helping reduce coating defects, paper breaks, and production instability.
Diameter: 500–1,500 mm
Face Length: 2,000–10,500 mm
Operating Speed: up to 2,000 m/min or higher
Roll Core Material: forged steel or high-strength carbon steel
Cover Material: rubber, polyurethane, or engineered elastomer
Cover Hardness: customized according to application requirements
Dynamic Balance: ISO 21940 G2.5
Runout Tolerance: typically ≤0.02 mm
Surface Finish: precision ground for uniform nip contact
The roll crown, cover hardness, and surface finish are critical factors affecting sizing performance.