Clay grease, most commonly known as Bentone grease, is a distinctive type of lubricant primarily developed using bentonite clay. It stands out in the world of industrial lubricants because of its unique high-temperature stability, earning it the designation of a non-melt lubricant.
This special grease type is engineered to perform exceptionally well in conditions where conventional, soap-based greases would typically melt and lose their lubricating properties.
Understanding Clay Grease Composition and Properties
Unlike most greases that use metallic soaps (like lithium, calcium, or aluminum) as thickeners, clay grease employs finely processed bentonite clay, a naturally occurring smectite clay. This clay acts as a gelling agent, forming a stable matrix that holds the base oil.
The key properties that define clay grease include:
- Non-Melting Property: A critical characteristic is that it has no known dropping point. This means it doesn't melt into a liquid state even under extreme heat, unlike soap-based greases that transition from a semi-solid to a liquid at their dropping point. This unique behavior is why it's called a non-melt lubricant.
- Exceptional Thermal Stability: The clay thickener maintains its structure and integrity at very high temperatures, preventing the grease from breaking down and ensuring continuous lubrication.
- Good Water Resistance: Clay greases generally offer good resistance to water washout and spray-off, making them suitable for damp or wet environments.
- Mechanical Stability: They typically maintain their consistency under shear and working conditions, resisting softening or hardening over time.
How Clay Grease Differs from Soap-Based Greases
The fundamental difference lies in their thickener system, which imparts distinct performance characteristics:
| Feature | Clay Grease (Bentone) | Soap-Based Grease (e.g., Lithium) |
|---|---|---|
| Thickener Type | Bentonite Clay | Metallic Soaps (Lithium, Calcium, Aluminum, etc.) |
| Dropping Point | None (Non-Melting); maintains structure at extreme temperatures | Specific Temperature; melts above this point |
| High-Temp Use | Excellent; ideal for continuous very high heat | Good; limited by the dropping point of the soap |
| Water Resistance | Good | Varies, often good (e.g., lithium complex offers excellent) |
| Typical Use | Ovens, kilns, foundry equipment, high-temp bearings | General purpose, automotive, industrial machinery |
Common Applications of Clay Grease
Due to its superior high-temperature performance, clay grease is invaluable in specialized industrial settings:
- High-Temperature Industrial Equipment: It is frequently used in equipment exposed to continuous and extreme heat, such as:
- Kilns and ovens in manufacturing plants (e.g., brick, cement, glass).
- Foundry equipment and steel mills.
- Asphalt plants.
- Bearings within high-temperature exhaust fans or drying systems.
- Bearings in Hot Environments: Any bearing application where conventional greases would melt and run out, leading to equipment failure, benefits from clay grease.
- Mining and Construction: Certain components in heavy machinery that generate significant heat can utilize clay grease for extended operational life.
- Specialty Applications: It's also found in niche areas requiring a lubricant that won't melt or drip, ensuring cleanliness and consistent performance.
Considerations for Using Clay Grease
While highly effective, there are a few points to consider when opting for clay grease:
- Compatibility: Mixing clay grease with other grease types is generally not recommended as it can degrade performance. Always consult product data sheets or perform compatibility tests.
- Pumpability: Some formulations might have different pumpability characteristics at very low temperatures compared to certain soap-based greases, though modern advancements have largely mitigated this.
- Cost: Clay greases can sometimes be more expensive than general-purpose lubricants, making them a specialized solution for demanding applications rather than a universal choice.
Clay grease offers a robust solution for lubrication challenges in extreme heat, making it an essential component in many heavy industries.
