A cast iron dryer cylinder is a large steam-heated cylindrical shell used in the dryer section of a paper machine. It is manufactured from high-strength cast iron and designed to operate under internal steam pressure while rotating continuously at high speed.
The paper web wraps around part of the dryer cylinder surface and is held in close contact by the dryer fabric. Heat from the steam inside the cylinder is transferred through the shell to the paper, evaporating moisture from the sheet.
Dryer cylinders are typically arranged in groups across the dryer section, forming a continuous drying system that gradually reduces paper moisture to the target level before calendering and winding.
In the papermaking process, drying is one of the most energy-intensive and technically critical stages. After the paper web leaves the forming and press sections, it still contains a large amount of moisture that must be removed before the paper can be finished, wound, and delivered as a final product. The component primarily responsible for this task is the Dryer Cylinder, and among all types of drying cylinders, the Cast Iron Dryer Cylinder remains the most widely used and trusted solution in the paper industry.
Installed in the dryer section of the paper machine, cast iron dryer cylinders provide a heated rotating surface that transfers thermal energy to the paper web. With steam entering the cylinder interior, the shell surface reaches a controlled temperature, allowing moisture in the paper to evaporate efficiently as the web passes over the cylinder surface with the support of dryer fabrics.
Because drying directly affects production speed, paper quality, energy consumption, and machine reliability, the performance of the dryer cylinder is of great importance in every paper mill.
1. Drying the Paper Web
The primary function of the dryer cylinder is to remove water from the paper web after pressing. By providing a heated surface, it evaporates moisture and raises the paper dryness to the level required for finishing and winding.
2. Improving Production Efficiency
Efficient drying allows the paper machine to run at higher speeds while maintaining the required final moisture content. A well-designed dryer cylinder improves heat transfer efficiency and supports stable, high-output production.
3. Supporting Paper Surface Quality
Stable drying conditions help maintain sheet flatness, reduce moisture variation, and support good surface appearance. Uniform temperature distribution is important for minimizing curl, wrinkles, and paper defects.
4. Reducing Energy Consumption
A dryer cylinder with good thermal efficiency and optimized surface performance can reduce steam waste and improve the energy efficiency of the dryer section.
Cylinder Diameter: 1,200–2,000 mm
Face Length: 2,000–10,500 mm
Shell Material: high-grade cast iron
Working Pressure: customized according to machine design and steam system
Surface Finish: precision machined and ground
Operating Speed: matched to paper machine speed, often up to 2,000 m/min
Dynamic Balance: precision balanced for stable rotation
Shell Thickness: engineered according to pressure and thermal load requirements
Journal Material: forged steel or alloy steel