Bearing is an important and indispensable part in machinery, and its service life has received more and more attention.But in daily use, we can obviously observe that under the same working conditions, the actual life of bearings with the same type of appearance is very different.

When the bearing inner ring is forced into the journal, the light will make the raceway at the bottom of the ring track serious wear, heavy in the slide, the outer ring and the ball will have cracks or peeling.

 *  Reason

The clearance between the ball and the slide is too small, the torque increases, the friction increases, and the working temperature of the bearing is too high, which aggravates the wear and fatigue of the bearing and leads to its failure.

*  Prevent method

Restore the radial clearance of bearings to reduce the amount of interference.

*  There are two inspection methods for bearing assembly quality:

a.Visual method: when the bearing chamber of the motor end cover is installed with the bearing, and the end cover is rotated by hand, if the bearing rotates freely and flexibly, without vibration and rocking up and down, it is deemed qualified.

b.The plug gauge inspection method: the motor end cover equipped with bearings is assembled on the base stop port, and the radial clearance of the bearing is checked with a 0.03mm thick plug gauge. If the maximum clearance position is just above the middle (the motor is installed horizontally), it is assembled correctly and reliably, otherwise, it is poorly installed.Should be adjusted properly the end cover position, reassembly, until qualified.

The reason is the serious lack of grease or grease drying aging.Due to the friction heat generated by the motor in high speed operation, the bearing temperature is too high and the oxidation becomes discolored, which is shown as the ball, cage, inner ring and shaft journal of the bearing turn brown or blue.

*Prevention method:

According to the motor running time, environmental temperature, load status, grease quality and so on four factors, determine its oil filling and oil changing time.Under normal circumstances, the motor running 6000~10000h should be filled oil 1 times;The oil should be changed once during the operation of 10000~20000h, and the oil change amount is 1/2~2/3 of the bearing chamber volume, and high-quality lithium grease should be used.

If the installation is not on the right, not only there are beads on the bearing slide, and the ball wear marks are uneven, but also produce deflection, the radial clearance on both sides of the bearing will be unequal with the gauge, and the difference is large.

* Reason

It may be struck directly through the outer ring of the bearing with an iron hammer;The belt is pulled too tightly (between gears);Make the center line of the driving wheel and the passive wheel not parallel.When the deflection is greater than 1/1000, the bearing operating temperature will be too high, the slide path and the ball ball will be seriously worn, the rotating shaft will be bent and the end cover bolt pressing surface is not perpendicular to the bolt axis.

* Correct installation method

With a steel tube sleeve with smooth end face and almost equal thickness to the bearing inner ring, the bearing is pressed on the correct position of the clean journal.Pressure into the force should be uniform, not too fierce.Then check the allowable yaw value of shaft end radial direction according to the different speed of the motor.

When the motor core has a fault, the bearing will vibrate strongly.

* Reason

The core is deformed by heat;Motor bearing aging;The bending deformation of the rotating shaft is large.The bolt of end cover stop loosens due to vibration;A weak foundation causes the bearing to vibrate.

The iron core is ground small, and the surface of the silicon steel sheet and the gap opened are soaked with silicone varnish 1052;Replace the new bearing of the same type;Exit the rotor core to straighten the bending part of the rotating shaft;180° symmetric method is adopted.Tighten the end cover stop bolt;Reinforce the foundation and tighten the anchor bolts.

If the metal material fatigue, bearing raceway and irregular fragments off the ball surface are mixed in the grease, the working noise will increase, the ball is sliding, resulting in the increase of the radial clearance of the bearing, and the allowable radial yaw value of the shaft end increases by 2~3 times.

The determinants of bearing fatigue degree include: motor load, speed, air gap, type of end cover, toughness of material, grease quality and grease loading amount.

*Prevent method

According to the operation record of the motor, when the light load working current is more than 60% of the rated value and it runs to 2000-25000h, the medium load working current is 60% to 80% of the rated value and it runs to 15,000-2000h, and the heavy load working current is 80% to 100% of the rated value and it runs to 10,000-15000h,The normal fatigue of bearing materials should be considered, and the new bearing of the same type should be replaced.

At this time, red and brown spots appear on the surface of the raceway and ball, and the working noise increases compared with the sound of the new bearing.

* Reason

The assembly place is not clean, if there is water vapor, acid, alkali and toxic gas;Contamination of tools and hands;Poor quality lubricating fingers were used.

* Prevent method

The assembly of bearings must keep the environment, tools and hands clean;Clean the bearing thoroughly;Replace high quality lithium grease.

If you have any questions about the bearing,pls feel free to contact us.

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