What are the types of plain bearings?

There are many types of bearings, but plain bearings are the most basic. A plain bearing is also called a sliding contact bearing or slide bearing, and is comprised of only a bearing surface and no rolling elements. In this type of bearing, a journal slides over a flat bearing surface. The simplest plain bearing is a shaft that rotates within a hole. Various other types of plain bearings are also available.

Self-lubricating plain bearings
Self-lubricating plain bearings are an effective way to reduce maintenance and labor costs. These bearings also extend the life of industrial equipment. Self-lubricating plain bearings are used almost everywhere from pivot points to slideways. They are also used in the drilling spindle of the Mars Curiosity rover. In addition to these uses, self-lubricating bearings are highly durable.

Self-lubricating plastic plain bearings have similar properties to metal-polymer-soluable bearings. They feature a thin polymer liner and a metal backing. The solid lubricant is displaced from the bearing to the shaft during movement. The main disadvantage of metal-polymer solutions is that they are prone to corrosion. Furthermore, they are not suitable for high-speed applications and oscillations.

Metal bushings
The primary difference between plain bearings with metal bushings and bronze bushings is the material of the bushings. Bronze is used because of its high strength. Brass is softer and deforms easily, but bronze is tough and holds its shape. Bronze bushings are shaped like sleeves, allowing them to help the bearing rotate efficiently. Bronze bushings are usually more expensive than plastic bushings, but they have many benefits including low maintenance, low friction, and self-lubrication. These components can be used in difficult to reach locations and without the risk of corrosion.

While metallic bushings offer higher mechanical strength and pv values, the choice of material should also be based on the framework conditions. In some cases, using polymer bushings is a more economical choice because they eliminate lubrication, making them an excellent choice for applications that require lower speed and dependability.

Polymer bushings
Metal-Polymer Bushings are a versatile option for industrial applications. They feature good wear and friction performance and are suitable for lubricated applications. The metal backing provides strength and stability while a porous bronze sintered layer improves dimensional stability and thermal conductivity. Polymers can also be treated with lubrication fillers to increase friction coefficient.

The selection of material for a plain bearing with polymer bushings should consider the amount of wear, friction, temperature, and running velocity. In addition, it is important to consider the range of materials available and determine if they are suitable for your application. Performance limits are usually based on optimum operating conditions and do not apply to all possible operating conditions. Specific material compatibility is important for each application.

Solid lubricants
A common type of plain bearing is a self-lubricating one, which can greatly reduce the cost of maintenance and labor. These types of bearings also improve the life of equipment. They are used virtually everywhere in industrial applications, from pivot points to slideways.

Standard grease is used in over 90% of bearing applications, but improper application can lead to premature bearing failures in up to 80% of cases. Solid lubrication eliminates the need for grease and provides a lifetime supply of oil. This allows maintenance technicians to focus on preventative work instead of re-lubricating. Solid lubricants for plain bearings can improve reliability by eliminating the need to change oil.

Applications
The various types of plain bearings are designed for specific purposes. Metal-polymer plain bearings, for example, are made up of a porous bronze inner structure with a polymer-resin lining. The polymer liner provides lubrication and low friction and wear while the bronze inner structure provides strength and mechanical integrity. Polymer-resin bearings are available in pre-lubricated and self-lubricating versions.

Plain bearings are generally made up of two parts, one fixed and one moving. The fixed part, or bush, bears the load, and the moving part, or sleeve, is in contact with the moving element. In order to minimize friction loss in the bearing, both surfaces are lubricated with a liquid or solid lubricant. The material used for lubrication is either graphite or Teflon. The moving and fixed surfaces have sliding friction, but the film of oil acts as a buffer.