Solid-lubricant bearings: what they are, benefits and applications

They prevent oil and grease leakage, offer resistance to contamination and chemical agents, and enable maintenance-free operation.

What is solid lubricant?

Along with oil and grease, solid lubricant is one of the solutions used to create a lubricating and protective film between moving surfaces.

Mainly composed of polymers, lubricating oil and additives, it appears as a solid plastic material at the macroscopic level, while under a microscope it reveals a microporous structure that, thanks to molecular forces, retains the lubricating oil within its pores.

During operation, factors such as acceleration, centrifugal force and rising temperatures promote the controlled release of oil from the micropores. The oil reaches the friction surfaces, ensuring proper lubrication. When operation stops, excess oil is reabsorbed by the polymer's porous structure.

This technology makes it possible to manufacture components and inserts in various shapes and sizes using dedicated moulds, including rods, rings, gears and sliders.

One of the main applications is BPO (Bearing Plastic Oil), a type of bearing incorporating solid lubricant.

These bearings are manufactured by injecting the polymer into the internal clearances of the bearing, where it solidifies and performs its lubricating function.

How do BPO bearings work?

In BPO bearings, the space normally left free between the rolling elements is filled with solid lubricant. Once solidified, it forms a body bonded to the cage and rotates together with it, progressively releasing the oil required for lubrication.

What are the advantages of solid-lubricant bearings?

Compared with bearings lubricated with oil or grease, BPO bearings offer several technical and performance benefits:

• Elimination of the risk of lubricant leakage, which is typical of oil- or grease-lubricated bearings.
• Improved performance at low temperatures, thanks to the solid lubricant polymer, which performs better than grease thickeners and allows BPO bearings to operate even at extremely low temperatures.
• High resistance to chemical agents, due to the greater chemical inertness of the polymer compared with the thickeners commonly used in greases.
• Reliable performance under demanding operating conditions, such as frequent starts and stops, bidirectional rotation, reciprocating movements (particularly small-amplitude, high-frequency oscillations), centrifugal forces and shock loads. These are all conditions in which conventionally lubricated bearings may be subject to premature wear.
• High resistance to contamination, further enhanced by the use of shields, which help protect the bearing against the ingress of solid or liquid contaminants.
• Improved corrosion resistance, as the solid lubricant creates an environment that discourages condensation from forming inside the bearing.
• Longer-lasting lubrication and maintenance-free operation, thanks to an oil content that is 2–4 times higher than that of bearings with standard lubricant.

Where are BPO bearings used?

Thanks to their specific characteristics, JFK Group solid-lubricant bearings are used across a wide range of industrial sectors and in particularly demanding operating conditions.

Industry	Application requirements
Food, beverage, tobacco and pharmaceuticals	Lubricant leakage is not permitted; cleaning and high-pressure washing; acidic or alkaline detergents and sterilizing agents
Textile and dyeing industry	Grease leakage from bearings is unacceptable; chemical agents in the environment
Lifts	Frequent start-stop cycles; difficult disassembly and maintenance; need to prevent lubricant leakage
Agricultural machinery	Exposure to dust, mud, rain and large temperature fluctuations
Mountain biking and cross-country cycling	Dust, water and mud; variations in speed and load
Automotive paint systems	Water and paint mixtures in the environment; need to reduce maintenance downtime
Robotics	Complex movements; frequent start-stop cycles
Oil drilling	Exposure to weather and large temperature fluctuations
Port lifting equipment	Frequent start-stop cycles; exposure to weather and temperature variations; complex maintenance and replacement
Medical equipment	Intermittent operation; strict hygiene and contamination prevention requirements

Do you have an application where conventional bearings fall short?

Find out whether BPO technology could be the right solution for your application.

Email us at info@jfk.group or contact our technical department.