Selection And Function Of ZZ Bearings

Time：2020.08.12  Source：Roller Bearings Suppliers

一. Selection of ZZ bearings

1. Selection of ZZ bearing model: ZZ bearing model is generally selected by the user's technical personnel according to the use conditions and load bearing of the supporting product. The business personnel mainly understand whether the actual load of the user is consistent with the selected ZZ bearing. If the ZZ bearing does not meet the requirements for use, the customer should be advised to change the model as soon as possible, but unless there is no problem in selecting the model for a special product.

2. The choice of ZZ bearing clearance: When purchasing ZZ bearings, users generally only inform the type and grade of ZZ bearings. They rarely ask for the clearance of ZZ bearings. Business personnel must ask about the use conditions of ZZ bearings and ZZ The bearing speed, temperature and fit tolerance are directly related to the choice of ZZ bearing clearance. Generally, motors with speeds below 3,500 rpm mostly use CM clearance. For example, high-temperature and high-speed motors require relatively large clearances. After assembly, the clearance of ZZ bearing will be reduced due to the expansion of the inner hole and the shrinking of the outer circle. The reduction of the clearance = interference × 60% (except the ZZ bearing housing is aluminum). For example, the clearance before assembly of ZZ bearing is 0.01mm, and the interference during assembly is 0.01mm, then the clearance after assembly of ZZ bearing is 0.004mm. In theory, the noise and life of the ZZ bearing reach the best state when there is zero clearance. However, considering the temperature rise in actual operation, the clearance of the ZZ bearing after assembly is 0.002mm-0.004mm.

3. Grease selection: The selection of grease is generally based on the speed, temperature resistance, noise requirements and starting torque of the ZZ bearing. The business personnel are required to have a good understanding of the performance of various greases.

4. Selection of ZZ bearing seal type: The lubrication of ZZ bearing can be divided into oil lubrication and grease lubrication. Oil-lubricated ZZ bearings are generally selected in the form of ZZ bearings, and grease-lubricated ZZ bearings are generally sealed with dust caps or rubber seals. The dust cover is suitable for high temperature or good use environment. The seals are divided into contact seal and non-contact seal. Contact seal has good dustproof performance but large starting torque, and non-connected seal has small starting torque but sealing performance No contact is good.

ZZ bearings are currently professionally manufactured in industries such as ZZ bearings for automotive motors, ZZ bearings for home appliances, ZZ bearings for motorcycles, and ZZ bearings for health care motors, so that the noise and life of ZZ bearings reach the best condition.

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二. Matters needing attention when using ZZ bearings

1. Tolerance selection and control of shaft and ZZ bearing chamber: After ZZ bearing is pressed into ZZ bearing, it should rotate flexibly without blocking. If the rotation is obviously not flexible, it indicates that the size of the shaft is too large and the tolerance needs to be lowered. If the ZZ bearing is pressed into the shaft and turned by hand, there is an obvious "sand" feeling, it may be because the tolerance of the shaft is too large or the roundness of the shaft is not good. Therefore, when controlling the tolerance of the shaft and the ZZ bearing chamber, the roundness must be controlled. At present, many domestic manufacturers only control the tolerance, but not the roundness.

2. The assembly method of ZZ bearings: Because ZZ bearings are high-precision products, improper assembly can easily cause damage to the ZZ bearing raceway and cause damage to the ZZ bearing. ZZ bearings should have special molds when assembling them, and they cannot be knocked at will. When pressing into the shaft, only small circles can be forced, and large circles can only be forced. When assembling, it is required to use air pressure or hydraulic pressure. The upper and lower molds should be outside the horizontal state during press-fitting. If there is a tilt, the ZZ bearing channel will be damaged due to force, which will cause the ZZ bearing to produce noise.

3. Prevention of assembly foreign matter: When ZZ bearing is installed on the rotor for dynamic balancing, it is easy to enter the iron filings generated during dynamic balancing into the ZZ bearing. Therefore, it is best to perform dynamic balancing before installing the ZZ bearing. For the convenience of assembly, some manufacturers apply some oil or grease in the ZZ bearing chamber for lubrication effect during assembly, but it is often difficult for operators to control the amount. If the oil or grease accumulates in the ZZ bearing chamber a lot, the ZZ bearing It is easy to enter the ZZ bearing along the shaft when rotating. It is best not to apply oil or grease to the ZZ bearing room. If it is not possible to apply it, it must be controlled not to accumulate in the ZZ bearing room.

4. Prevention of lacquer rust: The characteristic of lacquer rust is that it mostly occurs in sealed motors. The sound of the motor is very good during assembly, but after some time in the warehouse, the abnormal noise of the motor becomes very large. Remove the ZZ bearing There is severe rust. In the past, many manufacturers thought it was the problem of ZZ bearings. After our continuous publicity, now the motor factory has realized that the problem is mainly the insulating paint. This problem is mainly because the acidic substance volatilized from the insulating paint forms corrosive substances under a certain temperature and humidity, which causes the ZZ bearing to be damaged after corroding the ZZ bearing channel. At present, the problem can only be to choose a good insulating paint, and ventilate for a period of time after drying and assembly.

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The life of ZZ bearings is closely related to manufacturing, assembly, and use. Every link must be done well in order to make the ZZ bearings in the best operating state, thereby extending the service life of the ZZ bearings.

ZZ Bearing (Shanghai) Co., Ltd provides high quality and competitive price bearings. Our products export to more than 30 countries and regions around the world, and have established long-term cooperative relations with our customers. Customers are very satisfied with our products. In the future, we also hope that more customers can cooperate and develop with us.