Sliding bearings, also known as plain bearings or self-lubricating bushings, are fundamental components in mechanical systems where relative motion occurs between parts. With a simple design and reliable performance, sliding bearings provide low-friction support for shafts, pivots, and moving interfaces across a wide range of industries.

What Are Sliding Bearings?

Sliding bearings operate without rolling elements. Instead, a smooth bearing surface supports motion with minimal friction and wear. Thanks to their robust design, sliding bearings offer consistent performance in rotating, oscillating, and reciprocating motions even under heavy load or limited lubrication conditions.

Key Benefits of Sliding Bearings

Compared to rolling bearings, sliding bearings typically deliver:

High load-carrying capacity

Quiet, low-vibration operation

Resistance to shock loads and contamination

Simplified installation and maintenance

Their performance makes them ideal for industrial machinery, construction equipment, hydraulic systems, and more.

Core Sliding Bearing Solutions from Marginal Bearings

At Marginal Bearings, our sliding bearing products are engineered for durability, low friction, and dependable service in demanding applications:

•  Explore our Bimetallic Bushings range – optimized for heavy-load sliding motion:

• https://www.marginalbearings.com/bimetallic-bushings/

• Check out Carbon Steel Bushes for general-purpose sliding bearing applications:
  https://www.marginalbearings.com/carbon-steel-bushes/

• Choose Bronze Wrapped Bushings for enhanced load capacity and wear resistance:
  https://www.marginalbearings.com/bronze-wrapped-bushings/

• Browse Solid Bronze Turned Bushes for high-durability plain bearings:
  https://www.marginalbearings.com/solid-bronze-turned-bushes/

• These sliding bushes and plain bearing types support applications with heavy loads, oscillating motion, or limited lubrication environments.

Material Considerations for Sliding Bearings

Different bearing materials influence performance characteristics such as friction, wear-resistance, and load capacity. Typical materials include:

Metallic alloys (e.g., bimetal, bronze) for high-load and long-life applications

Self-lubricating composites with PTFE or polymer linings for maintenance-free motion
These materials help sliding bearings operate smoothly under diverse operating conditions.

Where Sliding Bearings Are Used

Sliding bearings are widely deployed in:

Industrial machinery and gear systems

Hydraulic cylinders and actuators

Construction and mining equipment

Material handling systems and pumps
Their capacity to function with low noise and robust load support makes them indispensable in many mechanical designs.

Why Choose Marginal Sliding Bearing Solutions

With a focus on quality and performance, Marginal Bearings has been manufacturing self-lubricating and plain sliding bearings since 2010. Our products are designed for reliability, corrosion resistance, and long service life in a variety of sectors—ensuring smooth, efficient motion for your machinery.

Ready to Find Your Sliding Bearing Solution?

Contact us to request a custom quotation or get technical support:
https://www.marginalbearings.com/contact-us 

More Introduction:

Abstract: This article mainly introduces the characteristics, materials, selection of lubricants for sliding bearings, as well as the failure modes and treatment methods of sliding bearings.

Keywords: sliding bearings; Material Science; failure

With the development of society, sliding bearings are becoming increasingly indispensable in modern mechanical equipment. Sliding bearings are becoming increasingly widely used in applications such as extremely high working speeds, large impacts and vibrations, limited radial space dimensions or the need for split installation, and working in water or corrosive media. At present, sliding bearings are widely used in rolling mills, steam turbines, internal combustion engines, railway locomotive level vehicles, metal cutting machine tools, aviation engine components, radar, satellite communication ground stations, astronomical telescopes, and various instruments. People are also paying more and more attention to sliding bearings.

1. Definition, classification, and characteristics of sliding bearings

Sliding bearings refer to bearings that operate under sliding friction. Sliding bearings work smoothly, reliably, and without noise. Under liquid lubrication conditions, the sliding surface is separated by lubricating oil without direct contact, which can greatly reduce friction loss and surface wear. The oil film also has a certain vibration absorption ability, but the starting friction resistance is relatively high. The part of the shaft supported by bearings is called the journal, and the parts that match the journal are called the bearing shells. The anti friction material layer cast on the inner surface of the bearing shell to improve its friction properties is called a bearing liner. The materials of bearing shells and bearing liners are collectively referred to as sliding bearing materials. The application of sliding bearings is generally under low-speed and heavy load conditions, or in operating parts where maintenance and lubrication are difficult. Sliding bearings can be divided into radial bearings and thrust bearings according to the different loads they bear, which respectively bear radial and axial loads; According to the different lubrication methods between their sliding surfaces, they can be divided into liquid lubricated bearings, partially liquid lubricated bearings, and self-lubricating bearings. Among them, liquid lubricated bearings are completely loaded by the oil film, while partially liquid lubricated bearings are in a state of boundary lubrication and mixed lubrication. Self lubricating bearings can work without adding lubricant during operation; According to the different bearing mechanisms of liquid lubrication, it can be divided into liquid dynamic pressure bearings and liquid static pressure bearings.

2. Bearing materials

The materials of bearing shells and bearing liners are collectively referred to as bearing materials. Bearing shells are key components in bearings, and their performance has a significant impact on the overall performance of the bearing. Sometimes, in order to save valuable alloy materials or due to structural needs, a layer of bearing alloy, namely the bearing liner mentioned above, is often cast or rolled on the inner surface of the bearing shell. The bearing material should have good friction compliance and embedment, good thermal conductivity, low coefficient of thermal expansion, wear resistance, corrosion resistance, strong anti bonding ability, sufficient mechanical strength and plasticity. The commonly used bearing materials can be divided into three categories: metallic materials (bearing alloys, copper alloys, etc.), porous metallic materials, and non-metallic materials such as engineering plastics, carbon graphite, etc. Among them, the bearing alloy has a low elastic modulus and elastic limit, but has good embeddedness, is easy to break in, and is not easy to bond; Copper alloy has good wear resistance and anti friction properties; Porous metal is a bearing material made by pressing and sintering different metal powders. It is porous and has self-lubricating properties; Non metallic materials are a rapidly developing type of material in recent years, with some particularly good properties. For example, polytetrafluoroethylene (PTFE) can work in strong acid environments and is not easily scratched on the surface of the mating partner.

3. Selection of lubricants for sliding bearings

The selection principle of lubricating grease: Lubricating grease has no cooling effect and is commonly used in bearings with low requirements, difficult to supply oil frequently, or low-speed heavy load and swinging motion. When the pressure is high and the sliding speed is low, the cone penetration of the lubricating grease should be greater. For high-speed bearings, choose lubricating grease with lower cone penetration and better mechanical stability for sliding bearings. It is particularly important to note that the viscosity of the base oil of the lubricating grease is lower. The drip point of lubricating grease should be about 20 ° C to 30 ° C higher than the working temperature to avoid the melting and loss of lubricating grease during operation. In the case of continuous operation at high temperatures, be careful not to exceed the allowable temperature range for the use of lubricating grease. In humid environments, moisture-proof calcium or aluminum based lubricating grease should be selected. Sodium based or composite calcium based lubricating grease should be selected at high temperatures. The principle of selecting lubricating oil: when the speed is high and the pressure is low, low viscosity lubricating oil should be selected, otherwise, slightly higher viscosity lubricating oil should be selected. The selection principle of solid lubricants: Solid lubricants can form a solid film to reduce frictional resistance, and are generally used in situations with special requirements, such as solid lubrication for harmonic gear reducers used in space robots.

4. Failure mode level treatment methods for sliding bearings

The main failure modes of sliding bearings include abrasive wear, scratching, bonding (biting), pulling, pitting, electrical corrosion, fatigue peeling, and corrosion. Common bearing fault handling methods: If the bearing is found to be overheated or stuck during movement, it should be stopped immediately for inspection, so that the rotor can continue to operate at low speed, or continue to supply oil for a period of time until the bearing shell cools down. Check whether the lubricating oil is sufficient and whether the rotor installation is aligned. The bearing shell with less damage due to sticking can be eliminated by scraping and grinding, and the bearing temperature rise should be strictly controlled. When abrasive wear occurs, check whether impurities are mixed in the oil. When scratches occur, check if it is due to impurities, foreign objects, and dirt mixed in the lubricating oil. When fatigue peeling occurs, check whether it is caused by vibration due to imbalance, or whether it is caused by shaft deflection, edge load, overload, etc. Pulling hair refers to the phenomenon where lubricating oil brings large particles of dirt into the bearing clearance and embeds them in the bearing bushing, causing hard scabs to form when the bearing comes into contact with the journal (or thrust plate). This can seriously scratch the surface of the shaft during operation. When pulling hair on bearings, attention should be paid to the cleanliness of the oil circuit, especially during maintenance, and metal shavings or dirt should be cleaned thoroughly. Cavitation refers to the formation of steam bubbles in the oil film due to unreasonable bearing structure (unreasonable oil stains on the bearing), shaft vibration, steam bubble rupture, and local vacuum on the surface of the bearing shell, causing small pieces to peel off and resulting in cavitation damage. Cavitation bearings can increase oil supply pressure, improve the shape of the bearing oil groove and oil groove, modify the edge or shape of the groove, improve the shape of the oil film streamline, reduce bearing clearance, reduce axis shaking, and replace with more suitable bearing material; Electric erosion refers to the formation of a certain voltage between the journal and the bearing due to poor insulation or grounding, or the generation of static electricity, which penetrates the oil film between the journal and the bearing and generates electric sparks, causing the bearing to become pockmarked. The insulation condition of the machine should be checked for electric corrosion bearings, especially paying attention to whether the wires of some protective devices (such as thermal resistors, thermocouples, etc.) are insulated properly. The grounding condition of the machine should be checked. If the damage after electric corrosion is not too serious, the shaft can be scraped and the shaft neck should be inspected. If there are electric corrosion pits on the shaft neck, the shaft neck should be polished to remove the pits.

5. Conclusion

Due to its unique advantages, sliding bearings have become an irreplaceable part of mechanical equipment. At present, people are paying more and more attention to the research of sliding bearings, which has led to some other forms of sliding bearings. For example, when the journal speed is extremely high, gas lubricated bearings can be used, which can greatly reduce the friction loss caused by liquid friction state. In addition, there are magnetic levitation bearings, and obviously, the prospects of sliding bearings are still bright.

2025 December 3rd Week Marginal Product Recommendation:

Material Specification Sheet–MG-6:

Material specification sheet – MG-6 is Ball and roller bearing steel according to EN ISO 683-17. Ball and roller bearing steel for balls and rollers of any dimension,rings and discs up to 30mm effective thickness.