Generally speaking, the common bearing materials can be divided into three types: metal materials, porous metal materials and non-metallic materials, and the most common material in our daily life is metal material bearing steel. What are the bearing materials? Based on the understanding of bearing materials, China bearing network shares relevant contents, and provides common defects of bearing materials and corresponding reasons, hoping to help you.

Common bearing materials include:

1. Metal material

Bearing alloy, bronze, aluminum base alloy, zinc base alloy and so on are all become metal materials. Among them, the bearing alloy, also known as white alloy, is mainly the alloy of lead, tin, antimony or other metals. It can have low strength under the conditions of heavy load and high speed. The reason is that it has good wear resistance, high plasticity, good saturation performance, good thermal conductivity, good adhesion resistance and good adsorption with oil. However, due to its high price, it must be poured on the bearing bush of bronze, steel strip or cast iron to form a thin coating.

(1) Bearing alloy (commonly known as Babbitt alloy or white alloy)

Bearing alloy is an alloy of tin, lead, antimony and copper. It takes tin or lead as the matrix and contains hard grains of antimony tin (sb SN) and copper tin (Cu SN). The hard grain plays an anti-wear role, while the soft matrix increases the plasticity of the material. The elastic modulus and elastic limit of bearing alloy are very low. Among all bearing materials, its Embeddedness and friction compliance are the best. It is easy to run in with the journal and is not easy to bite with the journal. However, the strength of the bearing alloy is very low, and the bearing bush cannot be made alone. It can only be attached to the bronze, steel or cast iron bearing bush as the bearing lining. Bearing alloy is suitable for heavy load, medium and high speed occasions, and the price is expensive.

(2) Copper alloy

Copper alloy has high strength, good antifriction and wear resistance. Bronze has better properties than brass and is the most commonly used material. Bronze includes tin bronze, lead bronze and aluminum bronze. Among them, tin bronze has the best antifriction and is widely used. However, tin bronze has higher hardness than bearing alloy and poor running in and embedment. It is suitable for heavy load and medium speed occasions. Lead bronze has strong adhesion resistance and is suitable for high-speed and heavy-duty bearings. Aluminum bronze has high strength and hardness and poor adhesion resistance. It is suitable for low-speed and heavy-duty bearings.

(3) Aluminum base alloy

Aluminum base bearing alloy has good corrosion resistance, high fatigue strength and good friction performance. These qualities make aluminum base alloys replace the more expensive bearing alloys and bronze in some fields. Aluminum base alloy can be made into single metal parts (such as shaft sleeve, bearing, etc.) or bimetallic parts. The bimetallic bearing bush takes aluminum base alloy as the bearing lining and steel as the backing.  

(4) Gray cast iron and wear-resistant cast iron

Ordinary gray iron or wear-resistant gray cast iron with nickel, chromium, titanium and other alloy components, or nodular cast iron, can be used as bearing materials. After the flake or spherical graphite in this kind of material is covered on the material surface, it can form a graphite layer for lubrication, so it has certain antifriction and wear resistance. In addition, graphite can absorb hydrocarbons and help improve the boundary lubrication performance. Therefore, when gray cast iron is used as bearing material, lubricating oil should be added. Due to the brittleness and poor running in performance of cast iron, it is only suitable for occasions with light load, low speed and no impact load.

2. Non metallic materials

The most widely used non-metallic materials are various plastics (polymer materials), such as phenolic resin, nylon, polytetrafluoroethylene, etc. The characteristics of polymer are: it does not react with many chemicals and has strong corrosion resistance; It has certain self lubrication, can work without lubrication, and has certain lubrication ability under high temperature conditions; Good embeddedness; The antifriction and wear resistance are relatively good.

When selecting polymer as bearing material, we must pay attention to the following problems: because the heat conduction capacity of polymer is only a few percent of that of steel, the dissipation of friction heat must be considered, which strictly limits the working speed and pressure value of polymer bearing. Because the linear expansion coefficient of polymer is much larger than that of steel, the gap between polymer bearing and steel journal should be larger than that of metal bearing. In addition, the strength and yield limit of polymer materials are low, so they can bear limited loads during assembly and work. Because polymer materials will creep at room temperature, it is not suitable to make bearings with strict clearance requirements.

Carbon graphite can be used as bearing material in bad environment. The more graphite content, the softer the material and the smaller the friction coefficient. Metal, polytetrafluoroethylene or molybdenum disulfide components can be added to carbon graphite materials, and liquid lubricants can also be impregnated. Carbon graphite bearing has self lubrication. Its self lubrication and antifriction depend on the amount of water vapor adsorbed. Carbon graphite has affinity with lubricants containing hydrocarbons, and the addition of lubricants helps to improve its boundary lubrication performance. In addition, it can also be used as water lubricated bearing material.

Rubber is mainly used where water is used as lubricant and the environment is dirty.

Wood has porous structure, and fillers can be used to improve its properties. Filled polymer can improve the dimensional stability of wood, reduce moisture absorption and improve strength. The bearing can be made of wood under extremely dusty working conditions.

3. Porous metal material

This is a bearing material made of different metal powders by pressing and sintering. This material is of porous structure, with pores accounting for about 10% ~ 35% of the volume. Before use, soak the bearing bush in hot oil for several hours to fill the pores with lubricating oil. Therefore, the bearing made of this material is usually called oil bearing. It is self-lubricating. During operation, due to the suction effect of journal rotation and the expansion effect of oil when the bearing is heated, the oil enters the friction surface for lubrication; When it is not working, the oil will be sucked back into the bearing due to capillary action, so it can work well even without lubricating oil for a long time. If oil is supplied regularly, the use effect is better. However, due to its small toughness, it should be used for stable without impact load and medium and low speed. Commonly used are porous iron and porous bronze. Porous iron is often used to make shaft sleeve of pulverizer, oil pump bushing of machine tool, camshaft bushing of internal combustion engine, etc. Porous bronze is often used to make bearings for phonograph players, electric fans, textile machinery and automobile generators. There are factories specialized in manufacturing oil bearing in China, which can be selected according to the design manual when necessary.

Powder metallurgy material is porous metal, which is a kind of powder material. It has porous structure. If it is immersed in lubricating oil, the micropores will be filled with lubricating oil and become oil-bearing, which has self-lubricating performance. Porous metal materials have low toughness and are only suitable for stable non impact load and medium and small speed.