Common Metal Bearing Material Characteristics And Applications
Bearing alloys, bronzes, aluminum-based alloys, and zinc-based alloys are all used as metal materials. Among them, bearing alloys, also known as white alloys, are mainly alloys of lead, tin, antimony or other metals, which can be used at low loads and high speeds. The reason is because of its characteristics, good wear resistance, high plasticity, good running performance, good thermal conductivity, good resistance to glue and good adhesion to oil. However, since it is more expensive, it must be poured on the bush of bronze, steel strip or cast iron to form a thinner coating.
(1) Bearing alloy (commonly known as babbitt or white alloy)
The bearing alloy is an alloy of tin, lead, antimony or copper. It is made of tin or lead as a matrix, and contains hard grains of antimony tin (Sb-Sn) and copper tin (Cu-Sn). Hard grains act as anti-wear and soft substrates increase the plasticity of the material. The bearing alloy has a low modulus of elasticity and a low elastic limit. Among all the bearing materials, it has the best embedding and friction compliance, and it is easy to wear with the journal and is not easy to bite with the journal. However, the strength of the bearing alloy is very low. It is not possible to make the bearing bush alone. It can only be attached to the bronze, steel or cast iron bearing bush for bearing lining. Bearing alloys are suitable for heavy-duty, medium-high-speed applications and are more expensive.
(2) Copper alloy
Copper alloys have higher strength, better friction reduction and wear resistance. Bronze is better than brass and is the most commonly used material. There are several types of bronze, such as tin bronze, lead bronze and aluminum bronze. Among them, tin bronze has the best friction reducing effect and is widely used. However, tin bronze is harder than bearing alloys, and has poor running-in and insertability, and is suitable for heavy-duty and medium-speed applications. Lead bronze has strong anti-adhesion ability and is suitable for high speed and heavy duty bearings. Aluminum bronze has high strength and hardness and poor adhesion resistance, and is suitable for low speed and heavy duty bearings.
(3) Aluminum-based alloy
Aluminum-based bearing alloys have good corrosion resistance and high fatigue strength, and the friction performance is also good. These qualities have made aluminum-based alloys replace the more expensive bearing alloys and bronzes in some areas. Aluminum-based alloys can be made into single-metal parts (such as bushings, bearings, etc.) or bi-metal parts. The bi-metal bushings are lined with aluminum-based alloys and lined with steel.
(4) Gray cast iron and wear-resistant cast iron
Ordinary gray iron or wear-resistant gray cast iron with alloy composition such as nickel, chromium or titanium, or ductile iron can be used as the bearing material. After the sheet or spheroidal graphite in this kind of material is covered on the surface of the material, a layer of lubricating graphite can be formed, so that it has certain friction reducing and wear resistance. In addition, graphite can adsorb hydrocarbons, which helps to improve the boundary lubrication performance. Therefore, when using gray cast iron as the bearing material, lubricating oil should be added. Because of its brittleness and poor running-in properties, it is only suitable for applications with light load and low speed and no impact load.
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