Self-lubricating metal bearings

Self-lubricating metal bearings are sliding bearings that have lubricant integrated into their structure, providing continuous lubrication without the need for an external supply. This design is ideal for high-load, high-temperature, or inaccessible applications where traditional lubrication is impractical or problematic.
Key Features and Benefits
Maintenance-Free Operation: These bearings eliminate or significantly reduce the need for periodic re-greasing, saving on maintenance costs and downtime.
Reliability in Harsh Environments: They perform reliably in extreme temperatures, underwater, in vacuum environments, and in dirty conditions where traditional lubricants might fail or attract contaminants.
High Load Capacity: The metal construction, often steel or bronze, provides the necessary structural strength and rigidity to support heavy loads.
Clean Operation: As they don't use external oil or grease, there is no risk of lubricant leakage, which is critical for hygiene-sensitive industries like food processing and medical devices.
Reduced System Complexity: They eliminate the need for costly external lubrication systems (pumps, filters, seals), simplifying machine design.
Types of Self-Lubricating Metal Bearings
Different types exist based on how the lubricant is integrated into the metal structure:
Sintered-Metal Bearings (Oil-Impregnated):
Description: These are made from porous metal powders (commonly bronze or iron) pressed and sintered to create a sponge-like structure with interconnected pores that are then impregnated with lubricating oil.
Mechanism: During operation, heat and pressure draw the oil to the surface, forming a lubricating film. When movement stops, capillary action reabsorbs the oil.
Use Cases: Suitable for moderate loads and speeds in small motors, household appliances, and automotive starters.
Graphite/Solid Lubricant Embedded Bearings (Oilless Bearings):
Description: Solid lubricants, such as graphite or molybdenum disulfide (MoS₂), are embedded into grooves or plugs within a solid metal matrix, typically cast bronze, brass, or iron.
Mechanism: The solid lubricant slowly transfers to the mating surface during movement, creating a stable, low-friction film that is effective at very high temperatures where oil would burn off.
Use Cases: Ideal for extreme temperatures (up to 400-600°C), heavy loads, low speeds, and applications involving radiation or underwater use, such as furnace doors, pumps, and heavy construction equipment.
Metal-Polymer Composite Bearings (Lined):
Description: These are multi-layer bearings with a steel or bronze backing, a porous sintered metal interlayer, and a thin, low-friction polymer sliding layer (e.g., PTFE or Acetal) with embedded solid lubricants.
Mechanism: A microscopic transfer film is formed on the shaft during initial use, providing continuous low friction.
Use Cases: Excellent for high loads, oscillating movements, and dirty environments, common in hydraulic pumps, suspension systems, and general industrial machinery.