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What are the benefits of preloading for bearings 

What is bearing preloading?

Generally, rolling bearings have a certain clearance in the working state. However, in order to achieve a specific purpose, when the bearing is arranged, the bearing obtains a certain internal load through a certain adjustment method, and is used in a negative clearance state, and this use method is called preload.

 

What are the benefits of preloading for bearings?

For rolling bearings, proper preload can have the following benefits:

 

1. Improve the rotation accuracy. After the bearing is preloaded, the internal clearance is eliminated, and each rolling element bears a certain preload, and the ring is supported from all directions, which can improve the rotation accuracy, so that the shaft can be correctly positioned in the axial and radial directions, and improve the rotation accuracy of the shaft, such as the spindle bearing of the machine tool and the measuring instrument.

 

2. Improve stiffness. The contact between the rolling element and the raceway is elastic, and the rolling element can be regarded as a spring. Bearings with clearance are supported by only a few springs in the direction of the force. The preloaded bearings are spring-supported in all directions, and there is a certain amount of preload, and the number of rolls that can bear the load is more than when there is a game, so the stiffness can be improved. In ball bearings, the relationship between the contact deformation of the ball and the channel and the load is nonlinear, and the contact stiffness increases with the increase of the preload.

 

3. Improve the life of the bearing. After preloading, the number of loaded rolling elements increases, the load on each rolling element decreases, and the load can be distributed on each rolling element relatively evenly, so the life of the bearing can be improved.

 

4. Improve the damping of the bearing and reduce the noise. The preload establishes a stable oil film between the rolling element and the raceway, improves the damping between the rolling element and the raceway, and can improve the dynamic characteristics of the supporting structure and reduce the noise.

 

5. Improve the dynamic performance of angular contact ball bearings. In high-speed rotating angular contact ball bearings, proper preload can prevent the gyroscopic rotation of the steel ball, prevent or reduce the rotational slippage of the steel ball, and also control the spin slip of the steel ball.

 

6. Suppress vibration marks and friction wear. The outer spherical bearing is actually a variant of the deep groove ball bearing, which is characterized by the spherical surface of the outer diameter of its outer ring, which can be matched into the corresponding concave spherical surface of the bearing seat to play the role of alignment. The outer spherical bearing is mainly used to bear the combined radial and axial load based on the radial load, and it is generally not suitable to bear the axial load alone. It is used for chatter-free machining of machine tools with low roughness, or in mechanisms where friction and wear need to be controlled when starting and stopping frequently.

 

7. Control the slippage phenomenon of rolling element rotation and rotation. Mounted outer spherical bearings are also designed to be self-aligned, easy to install, and have a double structure of sealing device that can work in harsh environments. The bearing seat is generally cast and formed. Mounted bearings are high-precision components that combine grease-sealed deep groove ball bearings and housings of various shapes. The bearing assembly can be mounted directly to the main body of the mechanism with a few bolts, and it is easy to install and use, such as self-alignment function and grease replenishment. For example, it is used in radial thrust ball bearings used in high-frequency motors and cylindrical roller bearings on jet engines.

Compensate for wear and tear during operation. The increase in clearance due to wear on the bearing during operation can be compensated for by preloading.