There are many reasons for the high heating temperature of bearings, and we have compiled several common problems for everyone.

Poor lubrication

Lubrication has a significant impact on the service life, friction, wear, vibration, etc. of bearings, and good lubrication is a necessary condition to ensure the normal operation of bearings. According to statistics, about 40% of bearing damage is related to poor lubrication.

The main effects of lubrication on bearings include:

1) Prevent metal corrosion

2) Prevent foreign objects from invading and provide a sealing effect

3) Remove frictional heat to prevent excessive bearing temperature rise

4) Reduce friction and wear, extend bearing life

The factors that usually cause poor lubrication of bearings include:

1) Insufficient lubricating oil (grease)

2) The lubricating oil pipe is blocked by foreign objects, etc

3) There is a problem with the quality of lubricating oil (grease)

4) Failure to add lubricating oil (grease) on time

5) The lubricating oil (grease) contains impurities

Bearing wear

The bearing continues to operate in a worn state, but due to increased friction and heat, the temperature of the bearing increases.

Improper installation

Improper installation is another important cause of bearing heating. Because the correct installation of bearings has a direct impact on their lifespan and host accuracy, it is required that the centerline of the shaft and bearing hole must coincide during installation.

If the bearing is not installed correctly, has low accuracy, and has deflection, torque will be generated during rotation, causing the bearing to heat or wear. In addition, bearings will also generate vibration, increase noise, and increase temperature rise.

Insufficient cooling

Insufficient cooling is usually manifested as blocked pipelines, improper selection of coolers, and poor cooling effectiveness.

Severe scaling of the cooler and frequent alarms due to high bearing temperature are common in many production sites. A more effective solution is to acid wash and descale the cooler before summer each year.

High vibration

Some rotors may experience unbalanced centrifugal force during operation due to corrosion from the medium, wear from solid impurities, or bending of the shaft, which can cause bearing heating, vibration, and severe wear of the raceway, leading to damage.

Delayed inspection and replacement

If severe fatigue peeling, oxidation rust, worn pits, cracks, or excessive noise are found in bearings that cannot be adjusted, if they are not replaced in a timely manner, it can cause heating, abnormal noise, vibration, and other conditions of the bearings, thereby affecting normal production.

Poor bearing quality

Rolling bearing parts work in the form of point contact or line contact under high alternating contact stress for a long time. The accuracy, lifespan, and reliability of the host machine largely depend on the bearings. Therefore, in the procurement and acceptance process of bearings, it is necessary to pay attention to inspection and use qualified and high-quality products from legitimate manufacturers.

Improper selection of bearings

When selecting bearings, attention should be paid to the maximum speed and load capacity of the bearing. They should not be used at excessive speed or load, as it will only shorten the service life of the bearing and not be worth the loss.

When the bearing temperature is high, the following aspects should be addressed first:

When the amount of oil added is improper, or there is too much or too little lubricating grease;

The bearing box should be regularly oiled according to the requirements of the work. After adding oil to the bearing, there may also be situations of high temperature, mainly due to excessive oil filling.

When the grease added does not meet the requirements or is contaminated;

Improper selection of lubricating grease makes it difficult to form a uniform lubricating oil film, which cannot reduce internal friction and wear of bearings. Insufficient lubrication leads to an increase in bearing temperature.

When different types of grease are mixed, chemical reactions may occur, causing the grease to deteriorate, clump, and reduce lubrication effectiveness.

Contamination of the grease can also increase the temperature of the bearing. During the process of adding grease, dust falls into the bearing, causing grease pollution, leading to deterioration of the grease inside the bearing box, damaging the bearing lubrication, and increasing the temperature.

Therefore, appropriate grease should be selected. During maintenance, the bearing box and bearings should be cleaned, and the refueling pipeline should be checked and unblocked. Different types of grease should not be mixed; If replacing other models of grease, the original grease should be cleaned first; During operation and maintenance, grease should be added regularly, and the grease should be properly stored for moisture-proof and dust-proof measures.

When there is insufficient cooling;

Check whether the pipeline is blocked, and whether the inlet oil temperature and return water temperature exceed the standard.

If the selection of the cooler is inappropriate, the cooling effect is poor, and it cannot meet the usage requirements, it should be replaced in a timely manner or a new cooler should be installed in parallel. The axial flow induced draft fan should also be checked for insulation and sealing of the core cylinder.

When there are no issues with the above aspects;

Bearing quality

Firstly, check if the lubricating grease has any deterioration, clumping, impurities or other adverse conditions, which is an important basis for determining the cause of bearing damage.

Secondly, check the bearings for damage and wear; Check the surface smoothness of the inner and outer rings, rolling elements, and cages of the bearings, as well as whether there are defects such as cracks, rust, peeling, pits, overheating and discoloration. Measure whether the bearing clearance exceeds the standard; Check the shaft sleeve for wear, pits, and peeling. If so, replace the bearing with a new one.

Matching of bearings

The fit between the inner diameter of the bearing and the shaft, as well as the outer diameter and the shell, is very important during bearing installation. When the fit is too loose, relative sliding occurs on the mating surface, which is called creep.

Once creep occurs, it will wear the mating surface, damage the shaft or casing, and the wear powder will invade the interior of the bearing, causing heating, vibration, and damage.

When the interference is too large, it will cause the outer diameter of the outer ring to decrease or the inner diameter of the inner ring to increase, reducing the internal clearance of the bearing.

To select a suitable bearing for its intended use, various factors such as the nature, size, temperature conditions, and rotation of the inner and outer rings of the bearing should be considered.

Adjustment of bearing clearance

If the bearing clearance is too small, due to the excessive shear friction loss of grease in the clearance, it can also cause the bearing to heat up. At the same time, if the clearance is too small, the amount of oil will decrease, and there is no time to take away the heat generated by friction, which will further increase the temperature rise of the bearing.