Multi-layer Bearings | PTFE & POM Bushes

Self-lubricating bearings are essential components in various industries, as they offer low maintenance and high performance. There are three primary types of self-lubricating bearings: multi-layer composite bearings, boundary lubricated bearings, and wrapped bronze bushings. Here is how you can distinguish between these three types of self-lubricating bearings:

1. Multi-layer Composite Bearings: These bearings consist of a multi-layered structure, typically with a steel or bronze backing, a porous intermediate layer, and a low-friction sliding layer. The intermediate layer is often made of a porous sintered material, such as bronze, that is impregnated with lubricant. The sliding layer, usually made of a PTFE-based material or other low-friction polymers, provides a smooth surface for the bearing to operate. These bearings are known for their high load-carrying capacity, low wear rate, and long service life.

Key features to identify multi-layer composite bearings:

• Steel or bronze backing layer
• Porous intermediate layer impregnated with lubricant
• Low-friction sliding layer on the bearing surface

2. Boundary Lubricated Bearings: Boundary lubricated bearings rely on a thin film of lubricant to separate the bearing surfaces during operation. The lubricant can be a solid or liquid, but it is typically applied only during assembly or maintenance intervals. These bearings may also have surface treatments, such as grooves or cavities, to help retain lubricant and reduce friction. They are typically used in applications where periodic maintenance is acceptable and environmental conditions are not severe.

Key features to identify boundary lubricated bearings:

• Thin film of lubricant between bearing surfaces
• Surface treatments to retain lubricant
• Periodic maintenance required

3. Wrapped Bronze Bushings: Wrapped bronze bushings are a type of self-lubricating bearing made of a single piece of bronze that is formed into a cylindrical shape. The bearing surface has pockets or grooves that are filled with solid lubricant, such as graphite or PTFE. As the bearing operates, the solid lubricant is released onto the contact surfaces, reducing friction and wear. These bearings are known for their high load capacity, resistance to corrosion, and adaptability to various temperatures and environmental conditions.

Key features to identify wrapped bronze bushings:

• Single-piece bronze construction
• Pockets or grooves filled with solid lubricant on the bearing surface
• High load capacity and resistance to corrosion

In summary, to distinguish between self-lubricated multi-layer composite bearings, boundary lubricated bearings, and wrapped bronze bushings, look for differences in their structure, lubrication method, and maintenance requirements. Multi-layer composite bearings have a layered structure with a lubricant-impregnated intermediate layer, while boundary lubricated bearings rely on a thin film of lubricant and wrapped bronze bushings are made of a single bronze piece with solid lubricant-filled pockets or grooves.

Multi-layer bearings are versatile and come in various combinations of sliding surfaces. One such combination is a 3-layer bearing, which consists of a copper-plated steel backing, a layer of POM (polyoxymethylene) or PTFE (polytetrafluoroethylene) with additives, and a tin layer. These bearings can be maintenance-free or require lubrication, depending on the application.

POM composite bushings and PTFE composite bushings can be machined to achieve the desired bore size, but they are generally ready for installation upon delivery. These bearings offer a wide range of benefits, such as low friction, wear resistance, and adaptability to different operating conditions.

Polyacetal multi-layer bearings, also known as POM composite plain bearings, have a bronze steel metal backing and are suitable for various lubrication conditions and temperature ranges. These bearings can operate at different temperature ranges, depending on the specific formulation of the POM or PTFE material.

Metal polymer composite bearings are three-layer self-lubricating bearings that can be custom-made to meet specific requirements. They typically have the following structure:

1. POM or PTFE with additives as the sliding layer
2. Tin or bronze powder as the intermediate layer
3. Sheet steel backing with a tin layer for additional corrosion protection

Chinese manufacturers of plain bearings offer a wide range of metal polymer bearings, which incorporate PTFE or POM as the sliding layer. These bearings are known for their excellent anti-friction and anti-wear properties.

Composite bearing structures can be classified into two categories: PTFE/POM-based bearings and thermoplastic bearings. Their operating performance is as follows:

1. PTFE/POM-based Self-Lubricating Metal-Polymer Bearings:

• Low friction
• High wear resistance
• Good chemical resistance
• Wide temperature range
• Suitable for dry, marginally lubricated, or fully lubricated conditions

2. Thermoplastic Tape-based Metal-Polymer Bearings:

• Excellent wear resistance
• High load-carrying capacity
• Good resistance to chemicals
• Adaptable to various temperature ranges

In summary, multi-layer bearings, particularly PTFE/POM-based and thermoplastic tape-based metal-polymer bearings, offer a versatile solution for various applications. They are known for their low friction, wear resistance, and adaptability to different operating conditions, making them an ideal choice for many industries.

Welcome to Plain Bearing Solutions, your friendly composite plain bearing specialists! As a highly experienced and flexible Chinese manufacturer of composite plain bearings, we provide a wide range of solutions to meet your unique requirements.

Composite dry plain bearings are designed for radial loads and require minimal radial space. These bearings facilitate reciprocating or rotational motion and are ideal for maintenance-free applications or where lubricants may be scarce.

DU and DX composite material bearings have a structure consisting of plastic, bronze, and steel backing. DU bearings are self-lubricating and can operate at temperatures between -200°C and 280°C with stress levels up to 250N/mm² without lubrication. DX bearings are pre-lubricated and can function at temperatures between -40°C and 130°C with stress levels up to 140N/mm² after initial lubrication.

The composite bearing structure includes a bearing housing containing a pre-lubricated DX bushing. Once it has been treated with SB lubricating grease, it can be used for an extended period without needing additional grease.

PTFE composite plain bearings are suitable for oil-free operation and offer several advantages:

• Static friction coefficient close, preventing “crawling” phenomenon
• Wide operating temperature range: -195°C to +270°C
• Good wear resistance, low friction coefficient, and long service life
• Excellent corrosion resistance in various corrosive media (including liquid and gas)
• High mechanical strength, capable of withstanding stable and dynamic loads
• Ability to reduce vibration and noise, improving the working environment

POM composite plain bearings are ideal for room temperature, low-speed, and medium-load applications. They can replace traditional copper sleeves, reducing costs and extending service life. In specific circumstances, they can reduce the frequency of lubrication and simplify replacement procedures, such as in rolling mills. These bearings have been widely utilized in various industries, including automobile chassis, forging machines, gold mining machinery, construction machinery, hydropower, and steel rolling.

To choose the correct composite bearing size, consider the following factors:

1. Load capacity: Determine the bearing’s load capacity based on the application’s requirements. Take into account static, dynamic, and shock loads, as well as any potential load variations during operation.
2. Shaft diameter: Measure the shaft diameter for which the bearing will be used, ensuring that the bearing’s inner diameter corresponds to the shaft size. It is essential to maintain proper clearance between the shaft and the bearing to avoid excessive friction or premature wear.
3. Bearing length: Consider the bearing length based on the required support for the shaft and the nature of the applied load. Longer bearings may provide better load distribution, but they can also increase the risk of edge loading and misalignment.
4. Operating temperature: Evaluate the operating temperature range of the application and choose a bearing material that can withstand the expected temperature fluctuations without compromising performance or service life.
5. Lubrication: Assess the lubrication requirements of the application. Some composite bearings are self-lubricating, while others may require periodic lubrication. Ensure that the chosen bearing is compatible with the lubrication method and frequency.
6. Environmental factors: Take into account any environmental factors, such as exposure to moisture, dust, or corrosive chemicals, which may affect the bearing’s performance or lifespan. Select a bearing material that offers the necessary corrosion resistance or protection for the specific environment.
7. Installation: Consider the ease of installation and maintenance for the chosen bearing size. Make sure that the bearing can be easily installed and replaced when necessary, and that it is compatible with the available installation tools and techniques.

By carefully considering these factors, you can select the appropriate composite bearing size for your application, ensuring reliable performance, reduced maintenance, and a longer service life.