What is the NLGI grade
The NLGI grade is defined by worked penetration — the lower the number, the softer the grease. Penetration is the depth (in 0.1 mm) a standard cone sinks into the grease at 25°C.
| NLGI grade | Worked penetration (0.1mm) | Consistency | Typical use |
|---|---|---|---|
| 000 | 445–475 | Semi-fluid | Centralized lubrication, gearboxes |
| 00 | 400–430 | Very soft | Enclosed gearboxes, low temperature |
| 0 | 355–385 | Soft | High speed, low-temperature small bearings |
| 1 | 310–340 | Medium-soft | General bearings, fan bearings |
| 2 | 265–295 | Medium (most common) | General industrial bearings |
| 3 | 220–250 | Firm | Large clearance, heavy load, vertical mounting |
Softer or firmer?
- Higher speed, lower temperature → softer grease (lower resistance);
- Heavier load, larger clearance, more vibration → firmer grease (prevents loss, resists squeeze).
Recommendations by scenario
- Miniature fans / precision bearings: NLGI 1 or 0;
- General industrial motor bearings: NLGI 2;
- Heavy-load, shock-load gears: NLGI 2–3 or with EP additives;
- Centralized lubrication / gearboxes: NLGI 000–00.
Conclusion
For most general applications, NLGI 2 is a safe choice; go softer (0/1) for high speed and low temperature, firmer (2/3) for heavy load and large clearance. Provide speed, load and temperature for engineering confirmation when unsure.