Precautions When Installing Bearings

Correct installation steps for bearings

1. Use special tools for bearing installation and disassembly

Using advanced installation tools can avoid bearing damage caused by improper tools and operations during installation. For example, when installing bearings, workers used the tapping method of copper rods, which could easily cause uneven axial stress on the bearings, cause deformation of the cage, damage to the rolling elements, and increase in clearance. In addition, during the tapping process, the copper rods Copper powder flies into the bearing cage, which can easily cause bearing failure.

2. Inspect the bearings before installation

For old bearings, check whether there are burrs, scratches, or cracks on the ball (column) surface. 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 whether the bearing model is correct. For the radial clearance standards of rolling bearings, refer to Table 1. 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 amount of the bearing can also be found to be 0.25mm.

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

When assembling the motor, it is also necessary to carefully check the matching dimensions of the bearing and the rotor shaft when the bearing is installed, and the matching dimensions of the bearing outer ring and the end cover hole.

4. Control the amount of oil in the bearings and bearing chambers

Too much oil in the bearing and box will cause the bearing rolling elements to slip, causing the rolling friction to change from rolling friction to sliding friction, damaging the bearing rolling elements. Due to the excessive amount of oil in the bearing, the free space in the bearing box will be small, and the operating temperature of the bearing will increase. As the temperature rises, the density of the grease decreases, the lubricating oil film on the rolling elements becomes thinner, and the lubrication conditions are poor, which can easily cause bearing noise, surface slippage, and shorten the life of the bearing. Generally, there is a bearing oil chamber on the side of the motor end cover (except for motors designed with double-sealed bearings). According to the motor speed, the amount of oil that can be filled into the bearing chamber can refer to the following standards: When the motor speed is <1500r/min, the amount of oil added to the bearing chamber is 2/3 of the volume. When the rotation speed is between 1500 and 3000r/min, it is 1/2 of the bearing chamber volume. When the rotation speed is >3000r/min, it should be less than or equal to 1/3 of the bearing volume. In the actual working process, for bearings operating at high temperatures and high speeds, bearings with sealing surfaces should be used as little as possible, the amount of oil stored in the motor oil cap should be increased, and a grease nozzle should be installed to extend the operating life of the motor bearings.

5. Pay attention to ensure that the insulation is intact

For bearings with an insulation design on the outer ring, care must be taken to ensure that the insulation is intact. If the bearing insulation is destroyed during installation, the very thin bearing oil film will be broken down by the shaft voltage. After the oil film is broken down, not only will the lubrication conditions of the rolling elements be poor, but the sparks generated will also cause electric corrosion of the bearing rolling elements, causing the rolling elements to malfunction. The surface is not shiny and accelerates bearing wear.

Some matters that should be paid attention to when installing bearings

When installing bearings, the most important thing is to keep the bearings and related parts clean and to use installation tools and methods correctly. Therefore, it is important to observe the following precautions:

1. Clean the working area and use clean tools or auxiliary tools for work.
2. When installing, you should use auxiliary tools with good plasticity and not easy to fall off.
3. Confirm that all assembled parts are qualified.
4. The bearing cannot be unsealed until it is used.
5. Keep the bearings clean during operation.
6. Under normal circumstances, the anti-rust oil does not need to be washed away. It can be installed in its original state. If it is necessary to install lubricating grease, use gasoline to clean the grease on the bearing, and then blow it clean with an air gun.