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Most people have wrong bearing installation problems, do you have any?

Posted on 2020-05-20 15:03 ET

Whether the bearing is installed correctly is related to the bearing's service life, so everyone must pay attention to it. This article will introduce the five steps of the correct installation of the bearing in detail.


    First, use specialized tools for bearing installation and disassembly.


    Advanced installation tools can avoid bearing damage caused by machines and improper operation during installation. For example, when installing the bearing, the staff used the copper rod knock-in method, which is likely to cause uneven axial force on the bearing, causing the cage to deform, the rolling element is damaged, the clearance becomes more substantial, and the copper rod is knocked during the process. The copper powder flies into the bearing cage, which may cause bearing failure.


    2. Check the bearings before installation


    For old bearings, check the balls (pillars) for burrs, scratches, and cracks. Whether the radial clearance and axial clearance of the old bearing are qualified, generally only the radial clearance is measured. For new bearings, first, check if the bearing model is correct. Refer to Table 1 for radial clearance standards of rolling bearings. For example, Model 6318 deep groove ball bearing, the inner diameter of the bearing is 90mm, the radial clearance range is 0.016 ~ 0.046mm, and the maximum wear of the bearing can also be found to be 0.25mm.

    3. Check the matching dimensions of the bearing and the rotor shaft


    When assembling the motor, it is also necessary to carefully check the comparable size of the bearing and the rotor shaft when the bearing is installed (Table 2), and the relative size of the outer bearing ring and the end cover hole.

    4. Control the number of bearings and oil in the bearing chamber.

    Too much oil in the bearing and the box will cause the bearing rolling body to slip, causing the rolling mass to change from rolling friction to sliding friction, and damage the bearing rolling body. Due to the excessive amount of bearing oil, the free space in the bearing box is small. The operating temperature of the bearing will be As it rises, the grease's hysteresis decreases, the lubricating film of the rolling element becomes thinner, and the lubrication conditions are poor, which can easily cause abnormal noise of the bearing, the surface slips, and shortens the life of the bearing. Generally, there is a bearing oil chamber on the side of the motor end cover (except for motors designed as double sealed bearings). According to the engine's speed, the amount of oil that can be injected into the bearing chamber can be implemented according to the following standards: When the motor speed is less than 1500r / min, the amount of oil in the bearing chamber 2/3 of the volume. When the rate is between 1500 ~ 3000r / min, it is 1/2 of the bulk of the bearing chamber. When the speed is more excellent than 3000r / min, it should be less than or equal to 1/3 of the bearing volume. In the actual work process, for bearings running at high temperatures and high speeds, bearings with sealing surfaces should be used as little as possible to increase the amount of oil stored in the motor oil cover, and a grease nipple is installed to improve the operating life of motor bearings.

    Five, pay attention to ensure that the insulation is intact.


    For bearings with an insulating design on the outer ring, care must be taken to ensure that the insulation is intact. If the bearing insulation is damaged during installation, the fragile bearing oil film will be broken down by the shaft voltage. After the oil film breaks down, not only will the rolling element's lubrication conditions be wrong, but also the electric sparks generated will cause electrical corrosion on the bearing rolling body, causing the rolling body The matte surface accelerates bearing wear.

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