High motor bearing temperature
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Dear experts, recently our 75Kw motors have shown high temperatures in the bearings at the shaft ends. The problem persisted even after replacing the bearings and the motors themselves, and replacing the lithium-based grease with different batches and models also did not help. Reasons for high bearing temperature and how to solve it.
What is the ambient temperature? What is the temperature of the motor bearings? What is the threshold for high temperatures? This is too vague to determine accurately
What’s the temperature? What’s the ambient temperature?
At an ambient temperature of around 25 degrees, the temperature at the bearing location can reach 90 degrees.
This temperature is indeed too high. How about the vibration?
An appropriate gap should be left between the bearing cover and the outer ring of the bearing; otherwise, if the bearing expands axially too much due to heat, it may overheat. When this phenomenon occurs, the front or rear bearing cover can be turned a little, or a thin shim can be placed between the bearing cover and the end cover to create sufficient clearance between the outer bearing cover at one end and the outer ring of the bearing.
There are three aspects you need to check carefully: 1, the origin of the bearings; whether they are domestic or imported, they may be fake. It’s not the case now that authorized dealers have a higher chance of winning. 2. Check the clearance between the motor and the driven machine’s idler wheels; ensure that an incorrect clearance in these wheels does not cause excessive axial force on the bearings. 3. Check the motor structure; there should be enough clearance for expansion in the bearing caps on both sides, which are of the 6300 type.
For genuine SKF and FAG bearings, please contact us. We have a professional technical team available to assist you with your questions. Phone number: 15063361231
What is the runout at the motor rotor bearing? Is the bearing clearance appropriate? Axial clearance of rotor positioning bearing? Are the other gaps appropriate?
The last edit to this post was made by qq_Peace Leads to Greatness 712712 on 2023-5-18 at 07:57. Pay special attention to the following points: 1. The clearance of the bearing itself, and whether the clearance series specified in the bearing model is correct； 2. Are the alignment data for the motor and the working machine normal? ； 3. Check and confirm the magnetic center line of the motor; verify whether, after the motor is turned on, axial displacement of the shaft occurs due to issues with the magnetic center line, thereby causing the bearings to experience axial thrust ； 4. Check the runout of the motor shaft and the shaft of the working machine ； 5. Calculate the expansion amount of the bearings (the clearance required for dual bearings) and the expansion amount of the pump shaft (the clearance provided by a single bearing) by using the temperature rise, the thermal expansion coefficient of each metal component, and the length. Provide sufficient clearance to avoid insufficient compensation for the bearing clearance due to expansion, which could prevent the bearings from functioning properly as temperatures rise ； 6. Check the quality of the oil – whether it is of normal quality, and whether there are any impurities or phenomena such as emulsification.