BMI bearings for paper mills are engineered for high-speed roll sections, extreme dryer heat, steam, moisture, and 24/7 continuous operation.
Function & Product Specifications
Pulp and paper mills demand maximum machine availability to stay profitable. BMI Bearings offers a complete bearing lineup for roll and dryer sections, with advanced nitrocarburizing treatment that increases ring strength, dimensional stability, and resistance to rolling contact fatigue. Focus is on reducing downtime, extending service intervals, and lowering total cost of ownership (TCO).
Common Specifications
- Nitrocarburizing Treatment: Advanced case-hardening process (diffused nitrogen and carbon) enhances surface hardness (≥ 700 HV), improves fatigue resistance, and provides superior dimensional stability at high temperatures – extends bearing life in dryer sections by up to 300%.
- Material: Through-hardened or case-carburized steel (8620 grade) – selected per application; nitrocarburizing applied for critical high-temp positions.
- Heat stabilization: Up to +200°C – specially stabilized for dryer roll operating conditions. Internal Clearance: C4 or C5 as standard – accommodates thermal expansion from roll heating.
- Cages: Machined brass or PEEK – for high-speed stability, low friction, and resistance to steam/chemical exposure.
- Sealing: Options include contact seals, labyrinth seals, and flinger discs – keep out pulp slurry, moisture, and cleaning chemicals.
- Surface finish: Raceways super-finished (Ra ≤ 0.15 µm) – minimizes friction at high speeds.
Operational Gains
- Increased machine availability – longer bearing life in critical roll and dryer positions.
- Reduced unplanned downtime – predictable service intervals based on actual mill data.
- Extended regreasing intervals – up to 3x longer than conventional bearings in dryer sections.
- Lower total cost of ownership (TCO) – fewer replacements, less lubricant consumption, and reduced labor.
- Enhanced dimensional stability – nitrocarburizing minimizes ring growth at high temperatures, preventing preload loss and vibration.
- Improved product quality – consistent roll alignment and minimal runout translate to better sheet formation and surface finish.
- Simplified maintenance – CARB bearings eliminate need for complex axial positioning adjustments.
- Corrosion resistance – nitrocarburized surface provides improved protection against steam and chemical attack.