According to the main criteria of bearing working capacity, the material of the bearing should have certain bearing capacity, embedding, thermal conductivity, low friction coefficient, smooth surface, anti-wear, anti-fatigue and corrosion resistance. No single material can fully satisfy all the requirements, which is why the compromise method is often used in most designs. The following is a brief introduction to the performance and application of several bearing materials:
Bearing alloys (babbitt) are widely used. They are usually available in two types: tin-based bearing alloys and lead-based bearing alloys, which have the characteristics of fast running and easy to smooth the surface. They are usually attached to the bearing pad of the steel as a bearing liner. Babbitt bearings have good adaptability and are self-adjusting for smaller misaligned or defective shafts. Since the proper amount of dust or foreign matter entering the lubricant can be absorbed by the soft material to prevent the gluing failure of the shaft, the embedding property makes them excellent bearing materials. The journal material can be mild steel, hard steel or cast iron.
Bronze bearings are suitable for low-speed and heavy-duty applications where the shaft and bearing are moderately neutral. They can be made from a variety of alloy compositions to achieve a variety of physical properties.
The bearing capacity of this kind of bearing is higher than that of the bearing alloy, and its adaptability is poor, so it is used in the case where the rigidity of the shaft is good and the neutrality is good.
Cast iron bearing materials are widely used in applications where the requirements are not critical. The hardness of the journal must be higher than the stiffness of the bearing. The working surface should be carefully run with a blend of graphite and oil. It is required that the journal and the bearing must be well centered.
The so-called "self-lubricating" or "porous" bearings can be made by first sintering the metal powder and then immersing it in oil. Bronze of various compositions is widely used on porous bearings with less iron. Due to the self-lubricating properties of porous bearings, it is mainly used in applications where it is difficult or impossible to obtain reliable lubrication when using general lubrication methods.
Pure carbon bearings can achieve satisfactory results in high temperature applications or when conventional lubrication methods cannot be used. Teflon is a very common plastic. The bearing made of it has a very low coefficient of friction and is used in the case of oil-free lubrication, it can work under low speed or intermittent swing and heavy load conditions. Experiments have shown that some combinations of materials work well together, while others do not. Excessive wear and tear will occur in combinations of materials that do not work well together.