What is Self-lubricating Bushing

Self-lubricating bushing, is a general name for a large category of products - the bushings that can achieve lubrication without adding extra lubricant, also the self-lubricating bearings include oil-impregnated bushings and composite bushings. The core principle is to automatically release the lubricant material through the lubricating element includes oil, solid lubricant of the material itself, or the structure design, such as the pore oil storage, to decrease the friction damage.

1.Oil-impregnated self-lubricating bearings

The most common products are powder metallurgy copper-based sleeves and iron-based sleeves. It is molded by pressing metal powder and high-temperature sintering, the internal will form countless pores, which will be impregnated by lubricant oil(machine oil, specialty lubricant oil, etc). When working, the rotation of the shaft generates frictional heat, the sleeves will have slightly expansion, so the oil will be came out from the pores and form the oil-film between the shaft and the sleeve; when stopping and cold out, the sleeve will be contraction, and the oil will be drawn back into the pores; repeating the processes. This oil-impregnated sleeves is cost-efficient, and suitable for the application with speed of ≤5m/s and load of ≤30MPa, example the motor rotor, conveyor belt rollers. The disadvantage is the oil film is easy to be damaged under the high speed or heavy load situation, and the life span will be decreased.

2. Solid self-lubricating bearings

This solid self-lubricating bearings achieve the lubricating through the solid lubricant material inside, such as graphite, PTFE, rather than the oil. The bearing is mainly consist by 2 material, the metal base is responsible for loading, and the lubricant impregnated in the holes, to add the lubricating film to continuously replenished to maintain lubrication effect.

Plugged self-lubricating bushings is made of metal as base, its mechanical strength depends on the properties of metal material. And the graphite acted as a solid lubricant material is plugged into the friction surface of metal base. The graphite material can be impregnated by oil, or itself also has lubricating performance. There are 2 methods to plug the graphite. One is the molten metal casting method, another one is to machining the holes on metal base firstly according to some lines, and then plug the graphite into the holes. The compression strength, bending strength, coefficient of expansion generally depend on the material of metal base. But the strength of graphite-plugged bushings is significantly increased, and can run under heavy loading. The plug method is superior to the casting method in terms of safety, pass rate, reliability, economy and process convenience.

Compare to the Oil-impregnated bearings, there are advantages of solid self-lubricating bushings:

1)Maintenance-free: No need for regular lubrication, reducing labor costs, especially suitable for difficult-to-maintain applications (such as high-altitude equipment and underwater components).

2)Adaptable to harsh environments: More durable than bearings that rely on external lubrication in environments lacking oil, dusty conditions, dampness, and corrosion.

3) Simple structure: Small size, can be directly made into a bushing form, saving installation space.

Semicorex offers high-quality graphite-plugged bushing or graphite plugs. If you have any inquiries or need additional details, please don't hesitate to get in touch with us.

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Email: sales@semicorex.com