Bearing selection 1. Selection of bearing model: The bearing model is generally selected by the user’s technical personnel based on the use conditions and load bearing of the supporting products. Business personnel mainly understand whether the actual load of the user is consistent with the selected bearing. If the bearing does not meet the usage requirements, the customer should be advised to change the model as soon as possible. However, unless there is a special product, there will generally be no problem in selecting the model. 2. Selection of bearing clearance: When purchasing a bearing, users generally only tell what model and grade it is, and rarely make requirements for the bearing’s clearance. Business personnel must ask clearly about the conditions of use of the bearing, the speed and temperature of the bearing. , fit tolerances are directly related to the selection of bearing clearance. Generally, motors with speeds below 3500 rpm mostly use CM clearance. For example, high-temperature and high-speed motors require relatively large clearance. After assembly, the bearing clearance will be reduced due to the enlargement of the inner hole and the shrinkage of the outer circle. The reduction in clearance = interference × 60% (except for the bearing chamber made of aluminum). For example, the clearance before assembly of the bearing is 0.01mm, and the interference during assembly is 0.01mm, then the clearance after assembly of the bearing is 0.004mm. In theory, the noise and service life of the bearing reach the optimal state when there is zero clearance. However, in actual operation, considering temperature rise and other issues, it is better for the bearing to have a clearance of 0.002mm-0.004mm after assembly. 3. Selection of grease: The selection of grease is generally based on the bearing’s rotation speed, temperature resistance, noise requirements and starting torque. It requires business personnel to have a good understanding of the performance of various greases. Selection of bearing seal type: Bearing lubrication can be divided into oil lubrication and grease lubrication. Oil-lubricated bearings generally use form bearings, while grease-lubricated bearings generally use dust caps or rubber seals for sealing. The dust cover is suitable for parts with high temperature or good use environment. The seals are divided into contact seals and non-contact seals. The contact seals have good dustproof performance but large starting torque. The non-contact seals have small starting torque but good sealing performance. Not as good as contact. Things to note when using bearings 1. Selection and control of tolerances of shaft and bearing chamber: after the bearing is pressed into the bearing, it should rotate flexibly without any sense of hindrance. If there is obvious rotational inflexibility, it means that the size of the shaft is too large and the tolerance needs to be reduced. If there is an obvious “sandy” feeling after the bearing is pressed into the shaft and turned by hand, it may be that the tolerance of the shaft is too large or the roundness of the shaft is not good. Therefore, when controlling the tolerances of the shaft and bearing chamber, the roundness must also be controlled. At present, many domestic manufacturers only control the tolerance and do not control the roundness. 2. Bearing assembly method: Because bearings are high-precision products, improper assembly can easily cause damage to the bearing grooves, leading to bearing damage. The bearing should have a special mold when assembling it, and cannot be knocked at will. When the shaft is pressed into the shaft, it can only bear force in a small circle, and when it is pressed in a large circle, it can only bear force in a large circle. It is required to use air pressure or hydraulic pressure during assembly. The upper and lower dies must be out of the horizontal state during press installation. If there is any tilt, the bearing channel will be damaged due to stress, causing the bearing to produce sound. 3. Prevention of foreign matter in assembly: When the bearing is installed on the rotor for dynamic balancing, it is easy for the iron filings generated during dynamic balancing to enter the inside of the bearing, so it is best to perform dynamic balancing before installing the bearing. In order to facilitate assembly, some manufacturers apply some oil or grease in the bearing chamber during assembly to achieve a lubricating effect. However, it is often difficult for the operator to control the amount well. If a large amount of oil or grease accumulates in the bearing chamber, it will easily cause trouble when the bearing rotates. It is easy to enter the inside of the bearing along the shaft. It is best not to apply oil or grease to the bearing chamber. If it must be applied, control it so that there is no accumulation in the bearing chamber. 4. Prevention of paint rust: The characteristic of paint rust is that it mostly occurs in sealed motors. The sound of the motor is very good when it is assembled, but after being placed in the warehouse for some time, the abnormal noise of the motor becomes louder and the bearings are removed. Severe rust. In the past, many manufacturers would think it was a bearing problem. After our continuous publicity, motor manufacturers have now realized that the main problem is the insulating paint. This problem is mainly because the acidic substances volatilized from the insulating paint form corrosive substances under certain temperatures and humidity, which corrode the bearing grooves and cause bearing damage. This problem can only be solved by choosing good insulating paint, ventilating it for a period of time after drying, and then assembling it. The life of the bearing is closely related to manufacturing, assembly and use. Every link must be done well to keep the bearing in the best operating condition and extend the service life of the bearing.  

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