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How to clean bearings correctly?Maintenance and overhaul of bearings

How to clean bearings correctly?Maintenance and overhaul of bearings


Bearings are widely used in various fields of national economy and national defense.The machinery and working environment of bearings vary greatly, so special attention should be paid to the maintenance of bearings and improve the service life of bearings.Bearing is a kind of precision parts, with high precision size, if improperly installed, will lose due precision and performance, serious will also cause bearing failure.Therefore, the bearing installation site and installation tools must be clean to prevent various particles into the bearing interior.Installation and disassembly of bearings should not be directly hammered, should be applied with uniform pressure, shaft and bearing fit interference is large, bearing should be heated immediately after installation.

Bearing failure usually causes production interruption, and the reasons for bearing failure in advance are mainly as follows:

1. Exceeding the limit operating temperature (below -30℃ or above 200℃)

2. Exposure to aggressive chemicals

3. Grease deteriorates quickly and needs to be lubricated frequently

4. Flammability of lubricant

5. Material compatibility

6. Dust or other pollution

How to clean the bearing?First of all, we need to remove the bearing and clean the bearing. The cleaning steps are as follows:

When the bearing is removed for inspection, first let the inspection personnel detect and take photos to record the appearance of the bearing.Then, confirm the amount of remaining lubricant and sample the lubricant, and finally clean the bearing.

Bearing cleaning is divided into rough washing and fine washing, and metal mesh frame can be placed at the bottom of the container in use.

Coarse washing, in the oil with a brush to remove grease or adhesion.It is best not to let the bearing rotate, so if the bearing rotates at this time, the impurities cleaned down may damage the bearing;Do not pile them up in the basket of parts for cleaning, they should be put up on a plane, this is to prevent in the cleaning process, the cleaning agent in the large residue will not gather in the groove of the bearing inner ring.

Use a separate cleaning tank for final cleaning to prevent contamination by other bearings being cleaned. The cleaning agent should be agitated during the cleaning process.

Pay attention not to steam cleaning of the conical surface. Oxygen and a lot of heat in the steam will make the bearing surface corroded and produce early defects.

After a rough wash, pour off the oil from the rough wash and then clean it.In fine washing, slowly turn the bearing in oil, pay attention to prevent foreign material damage to the shaft bearing.

The cleaning agent usually used is neutral water-free diesel oil or kerosene, and sometimes warm lye is used according to the need.No matter what kind of cleaning agent is needed to clean the residue, the need to keep clean through frequent filtration.Use the cleaning agent recommended by the manufacturer.

After cleaning, the bearing is coated with anti-rust oil or anti-rust grease immediately.The rust prevention period of bearings is half a year.The anti-rust period of general bearings is one year, and the anti-rust period of bushings with higher use requirements is two years.Bearings cannot be used in rust prevention period due to various reasons.When the bearing rust prevention period is reached, the original rust inhibitor should be removed.

If the cleaned bearing is not lubricated within 4 hours, it should be covered with paper soaked in lubricating grease, wound with protective paper and stored in a dry environment.

Maintenance of bearings

In order to judge whether the removed bearing can be used again, it is necessary to check the state of raceway surface, rolling surface and mating surface, cage wear, increase of bearing clearance and whether there is damage and abnormality about the decrease of dimensional accuracy after the bearing is cleaned.For non-separated ball bearings, use one hand to support the inner ring horizontally and rotate the outer ring to confirm whether it is smooth.

Tapered roller bearings and other separated bearings can check the raceway surface of the rolling body and outer ring respectively.Large bearings can not be rotated by hand, pay attention to check the appearance of the rolling body, raceway, cage, side surface and so on. The higher the importance of bearings, the more carefully they must be checked.

Whether it can be reused is determined by considering the degree of bearing damage, mechanical properties, importance, operating conditions, and the period to the next maintenance.However, new bearings must be replaced if the cage is worn significantly, or the rivet is slack significantly, the inner diameter surface of the inner ring or the outer diameter surface of the outer ring is creep significantly, cracks or notches in the inner ring, outer ring, rolling body or any one of the cage are observed.

There are significant stuck injuries on the raceway surface, guard edge and rolling body, serious indentation and marks on the raceway surface and rolling body, and obvious damage to the sealing ring or dust cover of the bearing sealed with grease.Any one of the ring and rolling body is broken, and there is rust and injury on the raceway surface and rolling body, and the discoloration caused by heat is obvious.

Storage of bearings

The storeroom shall not leak rain, the storage position of bearings shall avoid direct sunlight, and the indoor air shall circulate, but not be invaded by dust.The warehouse should be equipped with ventilation equipment and temperature regulation equipment.The warehouse should be kept dry, the relative temperature is controlled below 80%, the indoor temperature is controlled at about 25 degrees, and there should be no big temperature change day and night.If the temperature is too low, the rust releasing agent is easy to crystallize and crack, leading to corrosion of some metal exposed. If the temperature is too high, the rust releasing agent is easy to lose (evaporate) or deteriorate. The large temperature difference between day and night is easy to cause moisture condensation on the bearing surface and cause corrosion.In winter, bearing storage position should not be close to heating.The ground in the warehouse should be hard not easy to dust the ground.Bearings shall not be stored in a warehouse with acid, alkali, salt and other corrosive materials, chemical raw materials, materials with high moisture content.Storage of bearings around the warehouse is not easy to harmful gas intrusion.

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