Writer: Eric Bearing Limited
High bearing temperature is a common and harmful fault of rotating equipment, which will reduce the service life of the bearing and increase the maintenance cost. When the temperature rises rapidly and the temperature exceeds the standard, it is easy to cause unplanned shutdown or reduced load operation of the unit. Economic benefits have a great impact. Therefore, it is the guarantee of continuous and safe operation of the equipment to quickly determine the cause of the failure and take appropriate measures to solve it. Eric Bearing Limited lists the causes and solutions for the high temperature of TIMKEN bearings based on experience.
1. Common causes of high temperature of TIMKEN bearings
(1) Poor lubrication
If the lubrication is insufficient or over-lubricated, the quality of the lubricating oil does not meet the requirements, deteriorates or contains debris;
(2) Insufficient cooling
If the pipeline is blocked, the cooler is not suitable, and the cooling effect is poor;
(3) Abnormal bearing
If the bearing is damaged, the assembly process of the bearing is poor, and the gap adjustment of each part of the bearing box does not meet the requirements;
(4) Large vibration
If the coupling alignment process does not meet the requirements, the rotor has dynamic and static imbalance, the foundation rigidity is poor, the foot is virtual, rotating stall and surge.
2. The solution of TIMKEN bearing temperature is too high
When the bearing temperature is high, the problem should be solved from the following aspects:
(1) The amount of oil added is not appropriate, and the lubricating grease is too little or too much
The bearing box should be oiled regularly in accordance with the requirements of the work. TIMKEN bearings sometimes experience high temperature after refueling, mainly due to excessive refueling. At this time, the phenomenon is that the temperature continues to rise, and after reaching a certain point (usually about 10°C~15°C higher than the normal operating temperature), it will remain unchanged, and then gradually drop.
(2) The grease added to TIMKEN bearings does not meet the requirements or is contaminated
The selection of lubricating grease is improper, it is not easy to form a uniform lubricating film, and it cannot reduce the friction and wear inside the bearing. The lubrication is insufficient and the bearing temperature rises. When different types of grease are mixed, a chemical reaction may occur, causing the grease to deteriorate, agglomerate, and reduce the lubricating effect. Contaminated grease will also increase the temperature of the bearing. Dust will fall into the grease during the process of adding grease, causing grease pollution, resulting in the deterioration of grease in the bearing box, destroying the lubrication of the bearing, and increasing the temperature.
Therefore, appropriate grease should be selected, the bearing box and bearings should be cleaned during maintenance, and the fueling pipeline should be checked and dredged. Different types of greases are not allowed to be mixed. If you change other types of grease, you should clean up the original grease; operation and maintenance Add grease regularly, and the grease should be properly kept for moisture and dust prevention measures.
(3) Insufficient cooling
Check whether the pipeline is blocked, whether the inlet oil temperature and return water temperature exceed the standard. If the cooler is not properly selected and the cooling effect is poor, and cannot meet the requirements of use, it should be replaced in time or a new cooler should be installed in parallel. The axial flow induced draft fan should also check the insulation and sealing of the core tube. TIMKEN LL714649/LL714610 bearings online , pls click here :
(4) After confirming that there is no such problem, check the alignment of the coupling and the bearing
The alignment of the coupling must conform to the process standard. The thermal expansion of the equipment during operation should also be considered when aligning axial-flow induced draft fans and fluid couplings. Due to thermal expansion on the impeller side of the induced draft fan, the bearing box rises; the temperature rises during the operation of the fluid coupling, the bearing box expands, and the TIMKEN bearing rises, so the motor should be higher when aligning, and the size of the reserve depends on the characteristics of the equipment It depends on the temperature parameters during operation.
3. The inspection of TIMKEN bearings mainly has the following points
(1) The quality of TIMKEN bearings
During the disassembly of the bearing box, firstly, check whether the lubricating grease has deteriorated, agglomerated, impurities, etc. This is an important basis for judging the cause of bearing damage.
Secondly, check the bearing for seizure and wear;
Check the surface finish of the bearing inner and outer rings, rolling elements, cage, and whether there are defects such as cracks, rust, peeling, pits, overheating and discoloration.
Measure whether the bearing clearance exceeds the standard;
Check whether the shaft sleeve is worn, pits, peeling, if there is any above, replace the new TIMKEN bearing.
(2) The fit of TIMKEN bearings
When the TIMKEN bearing is installed, the inner diameter of the bearing and the shaft, outer diameter and the shell are very important. When the fit is too loose, relative sliding of the mating surface will be called creep. Once the creep occurs, it will wear the mating surface and damage the shaft or housing, and the wear powder will invade the inside of the bearing, causing heat, 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 TIMKEN bearing. In order to choose a suitable fit for the application, various factors such as the nature, size, temperature condition, and rotation of the inner ring and outer ring must be considered.
(3) Adjustment of the fit clearance of each part of TIMKEN bearing
TIMKEN bearing clearance is too small, due to the excessive shear friction loss of grease in the clearance, it will also cause bearing heating. At the same time, the clearance is too small, the oil volume will be reduced, too late to take away the heat generated by friction, which will further increase the temperature of the bearing Rise. However, excessive clearance will change the dynamic characteristics of the bearing and cause unstable operation of the rotor. Therefore, it is necessary to select the verified TIMKEN bearing clearance for different equipment and use conditions.