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What should I do if the bearing is hot?

Time:2020.01.27  Source:Roller Bearings Suppliers


Guide language: High bearing temperature is a common and harmful fault of rotating equipment, which will cut down the service life of the bearing, increase maintenance costs. When the temperature rises quickly, the temperature exceeds the limit, and it will lead to an unplanned unit shutdown or load reduction operation, which has a significant impact on economic benefits. Therefore, to quickly determine the cause of the fault and take appropriate measures to solve it is the guarantee of continuous safe operation of the equipment.

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Common causes of excessive bearing temperature:

1) Inadequate lubrication, such as insufficient or excessive lubrication, lubricating oil quality does not meet the requirements, deterioration or debris;

2) Inadequate cooling. If the pipeline is blocked, the cooler is not correctly selected, and the cooling effect is weak;

3) Abnormal bearing, such as bearing damage, inferior bearing assembly technology, taking box clearance adjustment does not meet the requirements;

4) Significant vibration, such as the coupling alignment process is imperfect and does not meet the criteria, rotor dynamic, and static imbalance, poor foundation rigidity, virtual foundation, rotating stall, and surge.

 

When the bearing temperature is high,  we should solve the problem  from the following aspects:

1) Improper amount of oil, too little or too much lubricating grease

The bearing box shall be lubricated regularly as required by the work. Bearing after refueling will sometimes appear high temperature, the main is too much refueling. At this point, the temperature continues to rise. After reaching a definite point (generally 10℃~15℃ higher than the average operating temperature), the temperature will remain unchanged and then gradually decrease.

2) Grease added to the bearing does not meet the requirements or is contaminated

The lubricating oil is not suitable to form a uniform lubricating film, which can not reduce the friction inner and wear of the bearing. When different types of oils and fats are mixed, chemical reactions may occur, resulting in deterioration and clumping of the oils and reducing the lubrication effect. Grease pollution will also increase the temperature of the bearing, which will fall into dust during the grease adding process, resulting in grease pollution, leading to the deterioration of oil inside the bearing box to damage the bearing lubrication and increase the temperature.

Therefore, the proper grease should be selected. During maintenance, the bearing box and bearing should be cleaned, and the oil line should be checked and dredge. Different types of grease can not be mixed.  Fat should be added regularly during operation and maintenance, and the fat should be kept appropriately for moisture-proof and dustproof measures.

3) Not enough cooling

Check whether the pipeline is blocked. Check whether the inlet temperature and return water temperature exceed the standard. If the cooler is not suitable for selection, weak cooling effect, can not meet the use of requirements, should be a timely replacement or parallel installation of a new cooler. The axial fan should also check the insulation and sealing of the core tube.

4) Check coupling alignment and bearing after confirming that there is no such problem

The search for the coupling is about to meet the technical standard. The thermal expansion of equipment in operation should also be considered in the timing of axial fans and hydraulic couplers. Due to the development of the impeller side of the induced fan, the bearing box rises; During the operation of the hydraulic coupler, the temperature increases, the bearing box expands, and the bearing increases. Therefore, the timing motor should be higher. The size of the reserved amount should be determined according to the characteristics of the equipment and the temperature parameters in operation.

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Bearing inspection mainly includes the following points:

1) Bearing quality

During the process of disassembling the bearing box, firstly, check whether the lubricating grease is rancid, caking, impurities, etc., which is an essential basis for judging the cause of bearing damage.Secondly, check whether the bearing is bitten and worn. Check the surface finish of the inner and outer ring of the bearing, the rolling body and the retainer, as well as the defects such as crack, rust, peeling, pitting, and overheat discoloration. And measure whether the clearance of the bearing exceeds the standard; Check whether there is wear, pit point, peeling if the situation should be replaced with new bearings.

2) Bearing coordination

It is essential to fit the inner diameter with the shaft, the outer diameter with the housing when the bearing is installed. If creep occurs, it will damage the wear surface, the pole or the house, and the wear powder will invade the inside of the bearing, causing heat, vibration, and damage. If the interference is too large, the outer diameter of the outer ring will become smaller, or the inner diameter of the inner circle will become more abundant, reducing the internal clearance of the bearing. To choose a suitable fit for the purpose, it is necessary to consider the properties of bearing load, size, temperature conditions, the rotation of the inner and outer rings of various diseases.

3) Adjust the matching clearance of carrying parts

If the Lagerluft is too small, the excessive loss of shear and friction of grease in the removal will also lead to the bearing heating. At the same time, if the consent is too small, the amount of oil will decrease, which will not take away the heat generated by friction and will further increase the temperature rise of the bearing. However, if the clearance is too large, it will change the dynamic characteristics of the bearing and the rotor operation will be unstable. Therefore, it is necessary to select and verify the bearing clearance for different equipment and service conditions.

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