What is a composite bearing

Bearings that are composed of different components (metals, plastics, solid lubricating materials) are called composite bearings, which are themselves plain bearings, and composite bearings, also known as bushings, pads or sleeve bearings, are usually cylindrical and contain no moving parts.

 

Standard configurations include cylindrical bearings for radial loads, flange bearings for radial and light axial loads, spacers and turn-over gaskets for heavy axial loads, and sliding plates of various shapes. Custom designs are also available, including special shapes, features (sump, holes, notches, tabs, etc.) and sizes.

 

Composite bearings are used for sliding, rotating, oscillating or reciprocating motion. Plain applications are commonly used as plain bearings, bearing gaskets, and wear plates. Sliding surfaces are usually flat, but can also be cylindrical and always move in a straight line, not a rotational motion. Rotary applications involve cylindrical faces and one or two directions of travel. Oscillating and reciprocating motion applications involve flat or cylindrical surfaces traveling in both directions.

 

The composite bearing construction can be solid or a split butt (wrapped bearing) for easy installation. Matching the bearing to the application is critical. High loads require bearings with increased contact area and high load carrying capacity. Solid lubricant bearings are designed to operate at higher temperatures than lubricating oil and grease lubricated bearings. High-temperature applications require special lubrication measures to minimize heat build-up and friction.

 

Composite bearings are manufactured in different structures. The choice of product depends on the operating conditions and performance requirements.

 

The types of low-friction bearing materials

 

Metal composite bearings consist of a metal backing (usually steel or copper) on which a porous copper interlayer is sintered, impregnated with PTFE and additives to obtain a running surface with anti-friction and high wear bearing properties. These bearings can be operated dry or externally lubricated.

 

Composite bearings can also be made of engineering plastics, which have excellent wear resistance and low friction properties, and are widely used in dry friction and lubrication operating conditions. Injection molded, which can be designed into almost any shape and is made from a variety of resins mixed with reinforcing fibers and solid lubricants. These bearings have excellent dimensional stability, low coefficient of friction and good thermal conductivity.

 

Fiber-reinforced composite bearings are another form of composite bearings, which are composed of filament-wound, fiberglass-impregnated, epoxy wear-resistant low-friction bearing linings and various backings. This construction allows the bearing to withstand high static and dynamic loads, and the material's inherent inertness makes it ideal for use in corrosive environments.

 

Monometal, bimetal, and sintered copper composite bearings are designed for use in land and underwater industrial applications, where they move slowly under high loads. Lubricant-impregnated solid copper bearings provide maintenance-free performance in high-temperature applications, while mono- and bimetal-based bearings are designed for lubrication applications.

 

The difference between composite bearings and rolling and needle roller bearings

 

There are significant differences between composite and rolling bearings, so they are not interchangeable.

 

1. Rolling bearings, due to their complex multi-component design, precision structure and precise installation, are often much more expensive than composite bearings.

2. Rolling bearings are more suitable for applications that require precise shaft position and/or very low friction.

3. Composite bearings, due to their larger contact area and adaptability, can provide higher load bearing capacity and resistance to high impact loads and concentrated loads at the ends.

4. Composite bearings compensate for misalignment better than some rolling bearings to reduce the impact of concentrated load at the end.

5. The composite bearing adopts ultra-thin single-piece design, which can reduce the size of the shell, save space and weight to a large extent.

6. The composite bearing has stronger resistance to reciprocating motion, which can prolong the life of the bearing.

7. The composite bearing will not be damaged by the wear caused by the sliding of the rolling elements when running at high speed and too low load, and has excellent damping performance.

8. Compared with rolling bearings, composite bearings have no moving parts inside, so they run more quietly and have almost no limit on speed under a properly lubricated system.

9. The installation of composite bearings is simple, only the machining shell is required, and it will hardly cause damage to the accessories compared with rolling bearings.

10. Compared with standard rolling bearings, non-metallic composite bearings have stronger corrosion resistance.

11. The composite bearing can be run dry without the cost of additional lubricant system, lubricant and equipment downtime during maintenance.

12. The composite bearing can be operated dry under the condition of high temperature and contaminants.