Plain bearings – find manufacturers and suppliers

Plain bearings are bearing types in which the bearing surface of the moving part slides directly on the bearing surface of the stationary part - in contrast to rolling bearings, in which balls or rollers act as an intermediate body.

They are one of the oldest and simplest bearing types and are used in a variety of machines, devices and systems to support rotating, oscillating or linear movements.

The following is an overview of the basic principle and design, the mode of operation, the materials of plain bearings, their areas of application, the materials and their advantages and disadvantages:

Basic principle and structure of plain bearings:

A plain bearing consists of a bearing shell or bushing and a shaft, axle or shaft that is supported in it.
There is often a lubricating film between the contact surfaces, which reduces friction and minimizes wear.
Depending on the design, the bearing can consist of a single material or be manufactured as a composite bearing with a carrier layer and a low-friction sliding layer.

How plain bearings work:

Movement in the plain bearing is achieved by the direct sliding of two surfaces against each other.
Friction is significantly reduced by lubrication:

1. Hydrodynamic lubrication: A lubricating film carries the entire load, direct contact is avoided
2. Hydrostatic lubrication: A lubricant is actively supplied under pressure.
3. Self-lubricating plain bearings: The lubricant is stored in porous structures or special polymer layers and released during operation.

Materials of plain bearings:

The choice of material depends on load, speed, environment and lubrication conditions. Common materials are:

1. Metals such as bronze, brass, aluminum alloys or sintered metal bushings.
2. Plastics such as PTFE, POM or UHMW-PE.
3. Ceramics for special, highly wear-resistant applications.
4. Composite materials in which a carrier layer, e.g. steel, is combined with a sliding layer.

Areas of application for plain bearings:

1. Mechanical engineering:
Bearing of shafts, levers or guides in machine tools, presses and conveyor systems.

2. Automotive engineering:
Suspensions, pedal bearings, joints, engine and gearbox applications.

3. Electric motors and fans:
Quiet, low-vibration bearings at moderate speeds.

4. Hydraulics and pneumatics:
Guidance of pistons or rods.

5. Household appliances:
Robust, cost-effective bearing supports for rotating parts.

6. Marine and offshore technology:
Bearings in water-bearing systems, often self-lubricating.

Properties of plain bearings:

• Plain bearings are characterized by a simple design, high load capacity and often a very compact design.
• Compared to rolling bearings, they can be particularly resistant to shock and vibration.
• However, the coefficient of friction depends heavily on the lubrication, the surface quality and the load.

Advantages of plain bearings:

The advantages include:

• Robust design
• Low sensitivity to shocks,
• Suitability for high loads at low speed
• Small size and often low cost.

Disadvantages of plain bearings:

The following properties can be disadvantageous:

• A higher coefficient of friction than rolling bearings.
• Increased lubrication requirement and lower efficiency at high speeds.
• An optimized lubrication method is required for many applications.

Plain bearings are proven, versatile bearing solutions that are primarily used where high loads, harsh environments or simple designs are required. Due to their adaptability to different materials and lubrication methods, they can be used efficiently in both low-cost mass applications and highly specialized industrial plants. The correct design in terms of material, lubrication and construction is crucial to minimize wear and ensure a long service life.

Here is an overview of the most important points to consider when purchasing plain bearings.

When purchasing plain bearings, it is crucial to consider not only the price and dimensions, but also a variety of technical, operational and environmental factors. The right choice ensures a long service life, reliable operation and minimal maintenance costs.

• Before making a selection, it must be clear which loads will act on the plain bearing: radial, axial or combined forces.
• Equally important is the type of movement - whether it is rotating, oscillating or linear.
• The load level in combination with the speed results in the so-called pv value (product of pressure and speed), which is decisive for the choice of material.
• The material of the bearing must match the load, speed and lubrication concept.
• Bronze or brass bearings are often suitable for high loads, plastic bearings for low-maintenance and corrosion-resistant applications, sintered bearings for self-lubrication.
• Composite materials can combine the advantages of several materials, e.g. steel as the carrier and PTFE as the sliding layer.
• The lubrication strategy directly influences the service life:
• Permanent or self-lubrication for maintenance-free applications.
• Regular lubrication for highly loaded or high-speed systems.
• Dry bearings for environments in which lubricants are not desirable.
• It should be clarified at the time of purchase whether the bearing must be equipped with lubrication grooves, holes or lubricant reservoirs.
• Dust, dirt, moisture, chemicals or extreme temperatures can have a significant impact on bearing performance.
• In corrosive environments, stainless steel or a corrosion-resistant plastic is recommended.
• At high temperatures, materials with appropriate heat resistance must be used; at low temperatures, materials that do not become brittle.
• The bearing bore and the bearing seat must be precisely matched to the shaft in order to ensure optimum lubrication film build-up and even load distribution.
• Too tight a fit increases friction and wear, too loose a fit causes play and vibrations.
• In addition to the purchase costs, the total costs over the life cycle are also important: replacement intervals, lubrication costs, downtime costs.
• A longer-lasting, higher-quality bearing can pay for itself through less downtime and lower maintenance costs, despite its higher price.
• Bearings should be manufactured in accordance with relevant standards such as ISO and DIN to ensure dimensional accuracy and interchangeability. Quality certificates, material tests and manufacturer information on load capacity, pv value and service life are important decision-making aids.
• Easy-to-install bearings with clear alignment and integrated installation aids save time and reduce the risk of installation errors.
• Where access is difficult, it may be advisable to choose pre-assembled or split bearing solutions.

Purchasing plain bearings requires a holistic approach that takes into account technical performance data, material properties, lubrication concept, environmental conditions and economic factors. Careful selection ensures smooth operation, extends the service life of the system and minimizes downtimes. Particularly in demanding environments, investing in high-quality materials and precision-manufactured bearings pays off many times over.

Bearings can be purchased from various suppliers. You will find comprehensive information on manufacturers and suppliers of Plain bearings around the world on Exportpages.