The bearing grease most often specified is rated NLGI Grade 2, and for good reason. This grease grade offers a unique combination of properties that make it ideal for a wide range of bearing applications. In this article, we will explore the NLGI rating system, the benefits of NLGI Grade 2 grease, and its proper application and maintenance.
The National Lubricating Grease Institute (NLGI) rating system classifies grease consistency on a scale from 000 to 6. NLGI Grade 2 grease has a consistency that is firm enough to stay in place but soft enough to be easily applied.
This makes it ideal for use in bearings that operate at moderate speeds and temperatures.
Understanding NLGI Ratings: The Bearing Grease Most Often Specified Is Rated Nlgi
The National Lubricating Grease Institute (NLGI) rating system classifies grease consistency based on its resistance to deformation. The NLGI scale ranges from 000 to 6, with 000 being the softest and 6 being the firmest.
| NLGI Grade | Consistency Range |
|---|---|
| 000 | Very soft, fluid-like |
| 00 | Soft, semi-fluid |
| 1 | Semi-solid, buttery |
| 2 | Firm, grease-like |
| 3 | Stiff, clay-like |
| 4 | Very stiff, blocky |
| 5 | Extremely stiff, fiber-like |
| 6 | Solid, soap-like |
Benefits of NLGI Grade 2 Grease
NLGI Grade 2 grease is ideal for bearing lubrication due to its firm, grease-like consistency. It provides the following benefits:
- Excellent adherence to bearing surfaces, reducing friction and wear
- Resistance to water washout and contamination
- Suitable for a wide temperature range, from -20°C to 120°C (-4°F to 248°F)
- Compatible with most bearing materials, including steel, bronze, and plastic
Common applications for NLGI Grade 2 grease include:
- Automotive and industrial bearings
- Electric motors
- Pumps and compressors
- Farm equipment
Comparison of Grease Types
| NLGI Grade | Consistency | Temperature Range | Applications |
|---|---|---|---|
| 000 | Very soft | -10°C to 40°C (14°F to 104°F) | Open gears, low-speed bearings |
| 00 | Soft | -10°C to 60°C (14°F to 140°F) | Low-speed bearings, chassis lubrication |
| 1 | Semi-solid | -20°C to 80°C (-4°F to 176°F) | General-purpose bearings, electric motors |
| 2 | Firm | -20°C to 120°C (-4°F to 248°F) | Automotive and industrial bearings, pumps |
| 3 | Stiff | 0°C to 140°C (32°F to 284°F) | High-temperature bearings, rolling mills |
| 4 | Very stiff | 20°C to 160°C (68°F to 320°F) | Severe-duty bearings, oven conveyors |
| 5 | Extremely stiff | 40°C to 180°C (104°F to 356°F) | Extreme-temperature bearings, kiln cars |
| 6 | Solid | 60°C to 200°C (140°F to 392°F) | Very high-temperature bearings, metalworking |
Proper Application and Maintenance
To ensure optimal bearing performance, NLGI Grade 2 grease should be applied correctly and maintained regularly.
- Clean the bearing surface and remove any old grease.
- Apply a thin, even layer of NLGI Grade 2 grease to the bearing surface.
- Lubricate bearings regularly, according to the manufacturer’s recommendations.
- Monitor bearing temperature and noise levels to detect any potential problems.
- Replace grease when it becomes contaminated or loses its effectiveness.
Industry Standards and Specifications
Several industry standards and specifications recommend NLGI Grade 2 grease for bearings, including:
- ANSI/AGMA 9005-A01: Lubrication of Industrial Enclosed Gear Drives
- ISO 6743-9: Lubricants, Industrial Oils and Related Products (Class L) – Family H (Hydraulic Oils)
- DIN 51502: Lubricants and Related Products – Classification and Application of Lubricants
These standards provide guidance on proper grease selection, application, and maintenance to ensure optimal bearing performance and longevity.
Case Studies and Applications
NLGI Grade 2 grease has been successfully used in various bearing applications, including:
- A manufacturing plant reduced bearing failures by 50% by switching to NLGI Grade 2 grease for its electric motors.
- A mining company extended the lifespan of its conveyor belt bearings by 25% by using NLGI Grade 2 grease in a harsh and dusty environment.
- A food processing plant improved the efficiency of its pumps by using NLGI Grade 2 grease, which reduced friction and energy consumption.
Questions and Answers
What is the NLGI rating system?
The NLGI rating system is a scale used to classify the consistency of grease. It ranges from 000 (very fluid) to 6 (very stiff).
What are the benefits of NLGI Grade 2 grease?
NLGI Grade 2 grease has a consistency that is firm enough to stay in place but soft enough to be easily applied. This makes it ideal for use in bearings that operate at moderate speeds and temperatures.
How do I apply NLGI Grade 2 grease to bearings?
NLGI Grade 2 grease can be applied to bearings using a grease gun or a brush. Be sure to apply the grease evenly and avoid over-greasing.
