Exploration of bearing raw materials, analysis of bearing materials, internal reference

We all know that there are many types of raw materials for related bearings, and different industries have different types of applications. The commonly used raw materials for bearings include three categories: metal composite materials, porous structured metal composite materials, and non-metallic materials.

Metal composite materials

Bearing alloys, brass, aluminum based alloys, zinc based alloys, etc. are all transformed into metal composite materials. Among them, bearing alloy, also known as white aluminum alloy, is the key aluminum alloy made of lead, tin, antimony or other metal materials. It can withstand light loads, high speeds, and other conditions with relatively low compressive strength. Due to its characteristics, it has good wear resistance, high plastic deformation, good running in characteristics, good heat transfer, strong adhesive resistance, and good adsorption capacity with oil. However, due to its high price, it is necessary to pour it onto the piston pins of brass, steel chains, or pig iron during application to produce a thinner coating. Commonly used for motor bearings, etc.

(1) Bearing alloy (collectively referred to as babbitt alloy or white aluminum alloy)

Bearing alloy is an aluminum alloy of tin, lead, antimony, and copper, which uses tin or lead as the PCB and contains hard crystals of antimony tin (Sb Sn) and copper tin (Cu Sn). Hard crystals have anti wear properties, while soft PCBs enhance the plastic deformation of raw materials. The elastic mold and ductility limit of bearing alloy are very low. Among all bearing raw materials, its insertion and friction compliance are the best. It is very easy to break in with the motor shaft during the running in period and is not easy to bite and stick with the motor shaft. However, the compressive strength of bearing alloys is very low, and piston pins cannot be made independently. They can only be attached to brass, steel, or pig iron piston pins as bearing liners. Bearing alloys are suitable for light loads, medium to high speeds, and are relatively expensive.

(2) Alloy copper

Alloy copper has high compressive strength, good anti friction and wear resistance. Copper is the most common raw material for improving the performance of brass. Brass can be classified into several types, including tin bronze, lead bronze, and aluminum bronze. Among them, tin bronze has the best anti friction properties and a wide range of applications. However, tin bronze has higher strength than bearing alloy, poor running in period and insertion ability, and is suitable for light loads and medium speed environments. Lead yellow copper has strong anti adhesion ability and is suitable for high-speed and light load bearings. Aluminum bronze has high compressive strength and resistance to adhesion, making it suitable for low-speed and light load bearings.

(3) Aluminum based alloy

Aluminum based bearing alloys have excellent corrosion resistance and high fatigue limits, as well as good friction characteristics. This quality has enabled aluminum based alloys to replace more expensive bearing alloys and brass in some industries. Aluminum based alloys can be made into single metal components (such as shaft sleeves, bearings, etc.), as well as bimetallic components. The bimetallic piston pin is lined with aluminum based alloys as the bearing liner and steel as the backing. (4) Steel castings and wear-resistant cast iron

Generally, gray iron or wear-resistant cast steel parts with nickel, chromium, titanium and other alloy components, or malleable cast iron, can be used as raw materials for bearings. The block or spherical high-purity graphite in this raw material, when covered on the surface of the raw material, can produce layers of high-purity graphite with moisturizing effects, thus possessing the necessary friction reduction and wear resistance. In addition, high-purity graphite can adsorb nitrogen oxides, which is beneficial for improving the limit wetting performance. Therefore, when selecting cast steel parts as bearing raw materials, lubricating grease needs to be added. Due to the brittleness of pig iron and its poor ability during the running in period, it is only suitable for low-speed gears with light loads and places without impact loads.

Non metallic materials

The most commonly used non-metallic materials are various plastics (high polymer raw materials), such as urea formaldehyde resin, polyester, PTFE, etc. The characteristics of polymers are that they do not react with many compounds and have strong corrosion resistance; Having the necessary self wetting ability, capable of working under non wetting standards, and possessing the necessary wetting ability under high temperature standards; Strong implantability; The friction reduction and wear resistance are both relatively good.

When selecting polymers as raw materials for bearings, it is important to pay attention to the following difficulties: because the thermal conductivity of polymers can only be a few percent of that of steel, it is necessary to consider the problem of dissipating frictional heat, which strictly limits the working speed ratio and working pressure value of polymer bearings. Due to the much larger expansion coefficient of polymers compared to steel, the gap between polymer bearings and steel motor shafts should be larger than that of metal bearings. In addition, the compressive strength and yield limit of high polymer raw materials are relatively low, so they have to bear insufficient loads during assembly line work. Because high polymer raw materials can experience stress relaxation under normal temperature conditions, they are not suitable for making bearings with strict clearance regulations.

Carbon high-purity graphite can be used as a bearing raw material in poor natural environments, where the higher the water content of high-purity graphite, the softer the raw material, and the lower the frictional resistance. Metal materials, PTFE or MoS2 multi-components can be added to carbon graphite materials, and liquid lubricants can also be pre immersed. Carbon high-purity graphite bearings have self-lubricating properties, and their self-lubricating and anti friction properties depend on the amount of water vapor they absorb. Carbon high-purity graphite and lubricants containing nitrogen oxides are infectious, and adding lubricants is beneficial for improving their boundary wetting performance. In addition, it can be used as a bearing raw material for hydration.

Vulcanized rubber is mainly used in places where water is used as a lubricant and the natural environment is relatively dirty.

Wood has a porous structure and can be improved with fillers to enhance its properties. Adding high polymer can improve the reliability of wood specifications, reduce moisture absorption, and enhance compressive strength. Bearings made of wood can work in dusty environments.

Porous structured metal composite materials

It is a bearing raw material made from different metal powders that have been suppressed and calcined. This type of raw material is porous, with a porosity of approximately 10% to 35% of the volume. Before application, the piston pin is pre immersed in rolling oil for several hours to fill the porosity with lubricating grease. Therefore, bearings made of this type of raw material are generally called oil bearings.

It has self wetting properties. During work, due to the suction effect of the motor shaft rotation and the swelling effect of the oil when the bearing is hot, the oil enters the friction surface and has a moisturizing effect; When not in operation, oil is sucked back into the bearing due to capillary action, so it can work very well even without lubricating grease for a very long time. If the fuel supply is interrupted on time, it is likely to lead to accidents, so the actual effect of the application is better. However, due to its small ductility, it is suitable for stable non impact loads and low to medium speed conditions. Common types include porous iron and porous brass. Porous structure iron is commonly used to make shaft sleeves for crushers, CNC lathes for gasoline pumps, and camshaft sleeves for gas turbine engines. many

Porous brass is commonly used to make bearings for record players, fans, textile equipment, and generators. In our country, there are professional processing plants that produce and manufacture oil containing bearings. When necessary, they can be adopted according to the design scheme guidelines.

Powder metallurgy materials are porous structured metallic materials, which are powdery raw materials with porous structures. If they are immersed in lubricating grease, the microporous plates will be filled with lubricating grease, becoming oil bearing materials with self-lubricating properties. Porous structured metal composite materials have low ductility and are only integrated into stable non impact loads and medium to low rate conditions.