What is an oil-free bearing

What is an oil-free bearing?

Oil-free bearing is a kind of novel lubrication bearing which has both the characteristics of metal bearing and oil-free lubrication bearing, the load is borne by the metal matrix, and the specially formulated solid lubricating material plays the role of lubrication. It has high bearing capacity, impact resistance, high temperature resistance, self-lubricating ability, etc. It is especially suitable for heavy load, low speed, reciprocating or oscillating occasions where it is difficult to lubricate and form oil film, and it is not afraid of water and other acid corrosion and scouring.

Bearing is a component that fixes and reduces the coefficient of friction of the load in the mechanical transmission process. Its main function is to support the mechanical rotating body and to reduce the friction coefficient of mechanical load in the transmission process of the equipment. According to the different frictional properties of the moving elements, bearings can be divided into two categories: rolling bearings and sliding bearings.
Most of the bearings in order to ensure that the bearings work smoothly and reliably, most of the added lubricating oil for lubrication, the purpose is to reduce the internal friction and wear of the bearings, to prevent burning sticky: extend the fatigue life of the bearings; discharge friction heat, or heat from the outside; at the same time, the oil film also has a certain vibration absorption capacity. However, added lubricating oil one of the biggest disadvantages is the need for good sealing performance, otherwise it will produce leakage, and some special requirements equipment does not allow the leakage of lubricating oil, so people use other lubricating materials to replace the lubricating oil, invented the oil-free bearings, so that it not only has the advantages of bearings containing lubricating oil, while eliminating the environmental pollution caused by leakage.

Classification of oil-free bearings

Oil-free bearings mainly include gas-lubricated bearings, composite material-lubricated bearings, water-lubricated bearings, etc.

Gas-lubricated bearings

Gas-lubricated bearing is a sliding bearing with gas as lubricant. The most commonly used gas lubricant for air, according to the need can also be used nitrogen, argon, hydrogen, helium or carbon dioxide, etc.. Gas-lubricated bearings to form a bearing gas film mechanism and liquid lubrication bearing the same. Gas lubrication bearing use of gas transmission f diffusivity, viscosity and thermal conductivity, adsorption and compressibility. So that in the friction between the vice, in the fluid dynamic pressure effect, static pressure effect and extrusion effect, the formation of a complete gas film, with the function of supporting the load, reduce friction.
Gas lubrication bearing is generally divided into gas dynamic pressure bearing, gas static pressure bearing and gas extrusion bearing three types. The actual bearing lubrication state often to dynamic, static pressure, dynamic, extrusion, static, extrusion and dynamic, static, extrusion mixed lubrication state form exists. Gas-lubricated bearings to form a bearing gas film mechanism and liquid-lubricated bearings the same.

Water-lubricated bearings

Since the 1970s, there is a crisis of oil resources and in recent years, people pay attention to environmental protection, hydraulic transmission technology is facing a serious challenge, water-lubricated bearings began to gradually promote the application. Water-lubricated bearings with water as the lubrication and working medium, not only save a lot of oil, but also can avoid the pollution of the environment with oil as the lubrication medium of traditional bearings. At the same time, water has no pollution, a wide range of sources, safety and incombustibility and other advantages, is an ideal lubrication medium. And also can reduce friction, wear, vibration, noise, reactive energy consumption and other key issues of the friction vice. Therefore, the research of water-lubricated bearings has important theoretical research and application value for improving mechanical efficiency and protecting the environment, which has become a hot spot of concern for all countries.

Metal-based solid inlay oil-free bearings

In the metal matrix, inlaid with graphite and MoS2 composite solid lubricants, a high-performance solid lubrication products. It breaks through the limitations of general bearings relying on oil film lubrication. In the process of use, the solid lubricant rubs with the shaft through frictional heat, forming excellent conditions of oil and powder coexistence lubrication, not only preserving the protection of the shaft from wear, but also making the solid lubrication characteristics eternal.

Its hardness is twice as high as general copper sleeve, and its wear resistance is also twice as high. At present, it has been widely used in metallurgy even casting machine, train bracket, steel rolling equipment, mining machinery, ships, gas turbines and other high temperature, high load, low speed heavy load and other occasions.

Composite material lubrication bearing

Due to the requirements of special production processes, certain key equipment in industrial and mining enterprises operate under extremely harsh working conditions. Due to heavy equipment, high ambient temperature, dust or air containing acidic corrosive gases, etc.. Lubrication of equipment brings a lot of problems, friction and wear, most of them are still using the traditional oil, grease lubrication, and the fact that these industrial and mining conditions have exceeded the scope of oil, grease lubrication. Bearings and other frictional vice bite or bite dead easily. Cause serious parts wear and damage, often leading to equipment downtime.
Composite material lubrication bearing using composite material is a new type of anti-pressure solid lubrication material, by the metal substrate and embedded in the substrate hole or slot of the solid lubricant paste composition. In the friction process, the metal substrate bears most of the load. After friction, the solid lubricant in the hole or slot is transferred or counter-transferred to the friction surface, forming a well-lubricated, firmly attached and uniformly covered solid transfer film on the friction surface, which greatly reduces frictional wear. With the friction, the embedded solid lubricant is continuously provided to the friction surface, which ensures good lubrication to the friction side during long-term operation.

Multi-layer composite oil-free bearing

It is a rolled sliding bearing with steel plate as the substrate, sintered spherical bronze powder in the middle and a mixture of polytetrafluoroethylene (PTFE) and lead rolled on the surface. It has the characteristics of small friction coefficient, good wear resistance, corrosion resistance and oil-free lubrication.
The use of this product can reduce the cost, reduce the size of machinery, to avoid the phenomenon of gnawing shaft and reduce mechanical noise and other advantages. The products have been widely used in the sliding parts of various machines, such as printing machines, elevators, textile machines, tobacco machines, fitness machines, hydraulic trucks, micro motors, solenoid valves, automobiles, motorcycles and household machinery.

Others

Linear bearings, non-standard parts, teflon soft tape, FB bronze bearings, JF bimetal bearings, SF-1 oil-free lubricated bearings, SF-2 boundary lubricated bearings, FZ steel ball cage series, powder metallurgy oil-containing bearings, graphite inlaid self-lubricating bushings, TF graphite loose inlaid alloy bearings, alloy inlaid high wear-resistant bearing shingles.

Installation instructions for oil-free bearings

• 1. It should be determined whether the mating surface of the shaft core and shaft housing has bump and protrusion.
• 2. Whether there is dust or casting sand attached to the surface of the bearing shell.
• 3. Although it is a small bump, protrusion, etc., if there is to remove with oil grinding stone or fine sandpaper.
• 4. In order to avoid bruising when capacitating, the surface of the shaft and the shaft housing should be wiped with a small amount of lubricant. To install the bearing in the shaft center, force should be applied to the inner ring, and to install the bearing in the bearing housing, force should be applied to the outer ring. To apply force to the bearing, make sure to make the force vertical and evenly down, bias will definitely make the bearing injured. For this reason, absolutely try to avoid bias play.
• 5. The oil-free bearing retainer and sealing plate should not be used to exert force. The installation method of using hammer and sleeve is a common method, because it will damage the bearing, so do not hit it directly. The sleeve should be in the middle and the hammer should not be pounded in. The hammer should be struck gently. In the construction of machinery, when the inner and outer rings are tightly fitted, the pad should be used to make sure that the force can be pressed into the inner and outer rings at the same time. If only the inner ring is pressed in, the force will be between the ball and pressed into the outer ring, therefore, it will cause scars on the track surface. To install the bearing with large margin on the shaft, the method of heating the bearing to 80~90 degrees in clean oil to make the inner diameter expand to install is widely used.
• 6. The hardness of the bearing is reduced by overheating, therefore, it must not exceed 100 degrees. In this case, the bearing must be suspended by steel wire or placed on top of metal wire frame or support plate, never on the bottom of the groove. When the bearing reaches the desired temperature (below 100 degrees), it should be taken out of the groove immediately and set into the shaft quickly. The bearing will shrink as the temperature drops, and sometimes a gap will be created between the shoulder and the bearing end face, so a tool is needed to press the bearing toward the shaft.

Principle of oil-free bearing

Self-lubricating bearings due to the requirements of special production processes, in fact, these conditions have gone beyond the scope of oil and grease lubrication, industrial and mining enterprises, some key equipment in extremely harsh conditions of operation, so far, most domestic enterprises still use the traditional oil and grease lubrication, due to heavy equipment, high ambient temperature, dust or acidic corrosive gases CO, SO2, etc., the lubrication of equipment brings many problems and serious friction and wear. Self-lubricating bearings are prone to galling or galling of bearings and other frictional subsets, resulting in serious wear and damage to parts, often leading to equipment failure.
Self-lubricating bearings in order to produce continuous operation in the original design in addition to the installation of multiple devices, automotive manufacturing, cement production, petrochemical and other enterprises have proposed to provide special lubricating materials under complex working conditions. Therefore, the study of mosaic self-lubricating composites, but also requires the installation of a large number of maintenance personnel. Serious constraints on productivity growth, consumption of parts and energy, has become an important obstacle to limit the development of production. Self-lubricating bearings in the material formulation and preparation process to highlight its own characteristics, material performance has reached the international advanced level, for enterprises to solve the problem of lubrication under special conditions, and bring obvious economic and social benefits.
However, due to many reasons, Chinese enterprises have not passed. The composite material used in the inlay self-lubricating bearing is a new type of pressure-resistant solid lubricating material. The self-lubricating bearing includes the metal base material and the solid lubricating paste embedded in the hole or slot of the bottom material. During the friction process, the metal matrix takes most of the load.
After the self-lubricating bearing is rubbed, the solid lubricant in the hole or groove will be transferred or reversed to the friction surface, and a well-lubricated, firmly bonded and uniformly covered solid transfer film will be formed on the friction surface, greatly reducing frictional wear. As the friction proceeds, the embedded solid lubricant is continuously supplied to the friction surface to ensure the long-term good lubrication of the friction sub.

Production process of oil-free bearing

Due to the requirements of production process, certain key equipment in industrial and mining enterprises operate under extremely harsh working conditions. Due to heavy equipment, high ambient temperature, dust or air containing acidic corrosive gas CO, sulfur dioxide, etc., the lubrication of the equipment brings many problems, friction and wear, so far, most of the above domestic enterprises are still using the traditional oil, grease lubrication, and the fact that these working conditions have exceeded the scope of oil, grease lubrication, extremely easy to occur in the bearing and other frictional vice of the bite or bite, causing serious Parts wear and damage, often leading to equipment downtime. In order to produce continuous operation, in addition to the original design requires the installation of multiple equipment rotation repair, but also must be invested in a large number of maintenance personnel. Seriously limit the productivity improvement, spare parts and energy consumption, has become an important obstacle to the development of production. Automobile manufacturing, cement production, petrochemical and other enterprises are proposed to provide complex working conditions under the special lubrication material requirements. To this end, the inlay self-lubricating composite materials research, in the material formulation and preparation process to highlight their own characteristics, material performance has reached the international advanced level, for the enterprise to solve the problem of lubrication under special working conditions, and brought obvious economic and social benefits. But due to a variety of reasons more domestic enterprises have not yet adopted, the above situation still exists.
Inlaid self-lubricating composite material is a new type of anti-pressure solid lubricating material, consisting of a metal substrate and a solid lubricant paste embedded in the hole or slot of the substrate. In the friction process, the metal substrate bears most of the load. After friction, the solid lubricant in the hole or slot is transferred or counter-transferred to the friction surface, forming a well-lubricated, firmly attached and uniformly covered solid transfer film on the friction surface, which greatly reduces frictional wear. As the friction proceeds, the embedded solid lubricant is continuously provided on the friction surface, ensuring good lubrication in long-term operation.

The advantages of oil-free lubrication bearing

• 1. Oil-free lubrication or low oil lubrication bearings are suitable for places where oiling is not possible or difficult. They can be used without maintenance or with less maintenance.
• 2. Good wear resistance, low friction coefficient and long service life.
• 3. Under proper elasto-plastic conditions, the stress can be distributed over a wide contact surface, thus improving the load-bearing capacity of shaft parts.
• 4. The static friction coefficient and dynamic friction coefficient are similar, which can eliminate low-speed creep, thus ensuring mechanical performance and working accuracy.
• 5. It can reduce vibration, lower noise, prevent pollution and improve working conditions.
• 6. During operation, it can form transfer film to protect the grinding shaft and will not bite the grinding shaft.
• 7. Low hardness of grinding spindle can be used without tempering treatment, thus grinding spindles can be used and the difficulty of machining related parts is reduced.
• 8. Thin-walled structure, light weight, can reduce the size of the machine.
• 9. Various metals can be plated on the steel back, which can be used in corrosive media. Used in sliding parts of various machinery, such as printing machines, textile machines, tobacco machinery, micro motors, automobiles, motorcycles and agricultural and forestry machinery, etc.

The development direction of oil-free bearings

• (1) In order to expand the use of gas-lubricated bearings, to improve the bearing stiffness and bearing capacity as the main goal, in the future, will be to develop high stiffness gas-lubricated bearing direction.
• (2) In order to meet the needs of high-tech and cutting-edge technology, to the direction of high precision, high performance gas-lubricated bearings.
• (3) In the design and process, through the manufacturing process of gas-lubricated bearings, work reliability, practicality and other aspects of research, development and development can be mass production of bearings, and bearing performance to have a simple structure, easy to manufacture, in the relevant equipment work reliably.

The research on water-lubricated bearings involves mechanical design, tribology, materials science, surface engineering, fluid mechanics, lubrication and sealing and other disciplines. Is a comprehensive scientific research project, the current water-lubricated bearing research is mainly in the following areas.

• (1) Based on the establishment of various types of materials high and low friction vice water lubrication theory.
• (2) With self-lubricating properties and good affinity with water water-lubricated bearing materials research.
• (3) Research on the mechanism of water-lubricated tribology based on surface engineering.
• (4) The verification of the theory requires particularly high experimental testing means; for composite bearings, the working conditions of the bearings such as temperature, load nature, load type, etc. are very complicated and there are many sizes and specifications.

How to select and design suitable materials according to different situations is a complex problem. The development of high temperature, heavy load, low speed, lining and corrosive and other complex working conditions of self-lubricating bearing materials is the urgent need.

Application of oil-free bearings

Plus boundary lubrication bearing: acid poly methyl with aldehyde, with high wear resistance, bearing surface with a regular arrangement with oil storage pit assembly must be coated with lubricating grease, especially suitable for high load and low speed under the rotary motion, swing motion and often under the load, opening and closing and not easy to form fluid lubrication parts, in the boundary lubrication conditions, can be used for a long time without refueling maintenance, and the process of refueling can make At present, it is suitable for metallurgical machinery, mining machinery, water conservancy machinery, auto parts, construction machinery, agricultural machinery, etc.
Oil-free self-lubricating bearings: The product is made of steel plate as the substrate, the middle layer of sintered spherical bronze powder, the surface layer of rolled polytetrafluoroethylene [ptfe] and lead mixture. It has a small coefficient of friction, wear and corrosion resistance. Oil-free self-lubrication and long service life, the use of it can reduce costs, reduce noise, prevent sticky, slippery. It is widely used in the sliding parts of various machinery such as printing machines, textile machines, hydraulic trucks, tobacco machines, pharmaceutical machinery, fitness equipment, micro motors, automobiles, motorcycles, etc.
Metal-based inlay solid self-lubricating bearing: is a novel lubrication bearing with both metal bearing characteristics and self-lubricating bearing characteristics, by the metal matrix to bear the load, the special formula of solid lubricating materials to play a lubricating role. It has high bearing capacity, impact resistance, high temperature resistance, self-lubricating ability and other characteristics. Traditional oil-containing bearings: Due to the advantages of low noise and self-lubrication, oil-containing bearings have become the new favorites of computer CPU fan bearings and are in high demand in the market; in addition, as people’s requirements for noise become higher and higher, the application of oil-containing bearings in daily household appliances is also expanding.
The basic requirements of bearings for materials depend largely on the working performance of bearings. The suitability of the material chosen for manufacturing rolling bearings will have a great influence on their performance and life. In general, the main form of damage to rolling bearings is fatigue spalling under the action of alternating stress, as well as the loss of bearing accuracy due to frictional wear. In addition, there are cracks, indentations, rust and other reasons for the abnormal destruction of the bearing. Therefore, rolling bearings should have high resistance to plastic deformation, less frictional wear, good rotational accuracy, good dimensional accuracy and stability, and long contact fatigue life. And many of these properties are determined by the material and heat treatment process together.

Source: China Oil-free Bearing Manufacturer – Yaang Pipe Industry (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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