The Fundamental Trade-Off
Open spherical roller bearings have been the industry standard for decades. They are versatile, can be relubricated in service, and are available in a wider range of sizes and configurations. Sealed spherical roller bearings (SB series) trade some of that flexibility for dramatically reduced maintenance requirements and superior contamination protection.
The question is not “which is better?” — it’s “which is better for your specific application?”
When to Choose Sealed (SB Series)
Choose sealed when:
- The bearing operates in a contaminated environment (dust, dirt, water, process material)
- The bearing location is difficult to access for relubrication
- Maintenance resources are limited or inconsistent
- The cost of downtime exceeds the cost of the bearing by a large margin
- The application runs at moderate speeds (< 1000 RPM for larger sizes)
Key advantages of sealed:
- Factory-filled industrial grease — grease type, temperature range, and application fit should be confirmed
- Multi-lip contact seals — superior exclusion of contaminants from day one
- Grease consumption review — compare open relubrication needs against sealed-bearing application limits
- Simplified machine design — no need for external seals, grease lines, or automatic lubricators
- Lower maintenance cost — less labor, fewer service visits
When to Choose Open
Choose open when:
- The bearing speed exceeds the sealed bearing’s limiting speed (seals generate heat at high speed)
- The operating temperature exceeds the seal material’s limit (typically 100–120°C for nitrile seals)
- The bearing is in a clean, controlled environment where contamination is not a concern
- Regular relubrication is part of a well-executed preventive maintenance program
- The bearing size or configuration is not available in a sealed version
Key advantages of open:
- Higher speed capability — no seal friction or heat generation
- Higher temperature capability — no seal material degradation
- Relubrication possible — fresh grease flushes contaminants and replenishes the lubricant film
- Wider availability — more sizes, more configurations, more cage options
Cost Comparison: Sealed vs Open
| Cost Factor | Open Bearing | Sealed (SB Series) |
|---|---|---|
| Bearing cost | Lower | Higher (+15–30%) |
| Housing/seal cost | Higher (external seals needed) | Lower (integrated seals) |
| Installation labor | Similar | Usually simpler |
| Relubrication labor | Requires regular service | None required |
| Grease consumption | Higher (regular relubrication) | Lower (factory fill only) |
| Unplanned downtime risk | Higher (contamination risk) | Lower (sealed protection) |
For many applications, sealed bearings may reduce maintenance labor and contamination risk, but the final cost review depends on speed, temperature, seal drag, quantity, and replacement context.
Application Examples
Mining conveyor pulley: SB series. Dust, water, and inaccessibility make open bearings a maintenance burden. Sealed bearings eliminate field lubrication and protect against contamination.
Steel mill run-out table: Open with C4 clearance. The extreme heat destroys seals. Relubrication with high-temperature grease is required.
Industrial fan (clean environment): Open standard SRB. Clean air, accessible location, and moderate temperature make open bearings the economical choice.
Construction equipment: SB series. Mud, dust, pressure washing, and inconsistent maintenance make sealed bearings essential.
Paper machine wet-end: SB series. Water and pulp contamination would destroy open bearings. Sealed bearings provide essential protection.