Size Press
PAPER MACHINE
Size Press
The size press is a unit installed in the dry end of the paper machine. Its main purpose is the surface application of aqueous starch solutions, sometimes enriched with other additives (such as resins, pigments, or dyes), in order to:
- Improve the strength and mechanical properties of the paper
- Increase resistance to water and ink penetration
- Optimize printability
Film Press
The film press is an alternative to the size press for the uniform and controlled application of a solution or suspension of additives on one or both sides of the paper web. The structure is similar to a size press, but includes two application heads with application rods, which apply a thin film of solution (starch or coating) to the surfaces of the two rolls. These rolls then transfer the solution onto the sheet in the press nip.
This system provides precise and even distribution of the chemical across the sheet surface, improving its printability.
The film press is particularly well-suited for high-speed machines and low basis weight papers.
Made in collaboration with DMS Industry
Comparison Between Size Press and Film Press
| Feature | Size Press | Film Press | |
|---|---|---|---|
| 1 | Working Principle | Partial immersion of the sheet in a pond between two rolls | Application of a liquid film via dosing rolls |
| 2 | Penetration into the sheet | High – due to pressure and immersion | Limited – more superficial application |
| 3 | Type of solution used | Low solids content solutions (typically 5–8%) | Medium-to-high solids content solutions (8–12%) |
| 4 | Coating uniformity | Medium | High |
| 5 | Basis weight control | Limited | Good |
| 6 | Viscous substance compatibility | Limited | Excellent |
| 7 | Maintenance and simplicity | Higher mechanical simplicity, easy to maintain | More complex, more expansive |
| 8 | Capital investment | Lower | Higher |
| 9 | Operational flexibility | High – allows fast grade changes | More rigid for certain applications |
| 10 | Reliability on lightweight grades | Better – penetration improves mechanical strength | Lower – higher breakage risk on thin papers |
