Why cooling fan grease needs dedicated selection
Cooling fan bearings are small, run at high speed and sit close to circuit boards, so the grease requirements are far more demanding than ordinary industrial bearings. The wrong grease causes noise, shortens life, or releases oil mist that contaminates nearby components.
Key selection factors
1. Operating temperature
- Consumer electronics fans: -20°C to 120°C, standard synthetic oil is enough;
- Large / high-temperature fans: 125°C to 165°C, use fully synthetic base oil with urea or PTFE thickener.
2. Speed and NLGI grade
- Miniature thin-wall bearings (high speed): choose soft NLGI 1 or 0 to reduce starting torque and cold drag;
- Heavier load, larger clearance bearings: NLGI 2 is acceptable.
3. Low evaporation and low noise
- Use low-volatility synthetic base oil to avoid high-temperature oil bleeding;
- Fine, high-cleanliness thickener, with factory noise and evaporation testing.
4. Material compatibility
The grease must be compatible with bearing cages, seals and plastic parts to avoid swelling or cracking.
Common selection mistakes
| Mistake | Consequence |
|---|---|
| Looking only at dropping point, not operating temperature | Oxidation and coking at high temperature, sharply reduced life |
| Using ordinary bearing grease instead of fan grease | High noise, high evaporation, circuit contamination |
| Grease too firm (NLGI 2+) | High starting resistance, low-temperature seizure |
Conclusion
Prioritize operating temperature, low evaporation, low noise and correct consistency. When unsure, provide bearing clearance, speed and temperature for engineering confirmation.