Why is Bearing Lubrication Critical?
During bearing operation, metal-to-metal contact between rolling elements and raceways generates friction. Without lubrication, the friction coefficient can reach 0.1~0.3, causing rapid temperature rise and severe wear. Proper lubrication forms an oil film that reduces the friction coefficient to 0.001~0.005, while achieving three core functions:
- Wear Reduction: The oil film separates metal surfaces to minimize direct abrasion
- Heat Dissipation: Removes frictional heat to prevent overheating
- Sealing & Protection: Blocks dust and moisture to avoid corrosion
Industry Data: Over 50% of premature bearing failures are caused by improper lubrication (e.g., excessive grease, wrong type selection, delayed maintenance).
Core Lubrication Types: Grease vs Oil
Grease Lubrication
Suitable for low-speed, medium-temperature, dusty scenarios (e.g., mining machinery, motor bearings)
Long Maintenance Interval
No Complex System
Fill Volume: 1/3~1/2 of bearing internal space (excess causes overheating).
Oil Lubrication
Suitable for high-speed, high-temperature, heavy-load scenarios (e.g., machine tool spindles, turbine generators)
Low Friction Coefficient
Recyclable & Cleanable
Common Methods: Oil bath lubrication, splash lubrication, forced circulation lubrication.
Lubricant Selection: 3 Key Factors
| Selection Factor | Key Requirements | Example |
|---|---|---|
| Temperature Range | Oxidation-resistant for high temps; low-viscosity for low temps | Synthetic grease for high-temp bearings (>120℃) |
| Operating Speed | Low viscosity for high speed; high viscosity for low-speed heavy loads | Low-viscosity oil for high-speed machine tool spindles |
| Environmental Conditions | Rust-resistant for humid/corrosive environments; seal-friendly for dusty areas | Food-grade lubricant for food machinery; anti-sand grease for wind turbine bearings |
Common Lubrication Issues & Fixes
Caution: Do not mix different types of lubricants (e.g., mineral oil & synthetic oil) — chemical reactions may cause lubrication failure.
-
Issue 1: Abnormal Bearing Temperature Rise
Causes: Excessive/insufficient lubricant, wrong type, contamination
Fixes: Adjust volume, replace with suitable lubricant, clean and relubricate bearings -
Issue 2: Unusual Operating Noise
Causes: Insufficient lubrication, aged lubricant, foreign particle intrusion
Fixes: Add lubricant, replace with new lubricant, inspect sealing system -
Issue 3: Lubricant Leakage
Causes: Damaged seals, overfilling, lubricant thinning due to high temperature
Fixes: Replace seals, adjust fill volume, use high-temperature resistant lubricant
Recommended Maintenance Schedule
Daily Inspection
Frequency: Daily/Before Startup
Tasks: Check temperature, listen for noise, inspect leakage
Periodic Maintenance
Frequency: Weekly/Monthly
Tasks: Refill lubricant, check lubricant condition
Comprehensive Service
Frequency: 3~12 Months
Tasks: Replace lubricant, inspect wear, replace seals
6. Conclusion
Bearing lubrication is not just “simple oiling” — it is a systematic process based on working conditions. Choosing the right lubrication type, using appropriate lubricants, and conducting regular maintenance can extend bearing life by over 50%, while reducing equipment failure rates and maintenance costs. It is recommended that enterprises establish a “lubrication management ledger” to record lubricant type, replacement time, and inspection results for full-cycle traceability.