Reasons for large axial vibration of the fan
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One of the fans manufactured by our company has a horizontal vibration of 3 mm/s, a vertical vibration of 2.5 mm/s, and an axial vibration of 9.5 mm/s. The fan rotates at 2900 rpm, uses a D-type drive, and the impeller diameter is 1060 mm; I’m not sure what the reason is.
Can it still operate with such a large vibration! It mainly checks the balance of the impeller. Also: With such large axial vibrations, if it is vibration of the entire unit, the fan’s supports need to be checked ； If it is only rotor vibration, check the fan bearings.
If there is a imbalance, the vibration is primarily manifested in the radial direction. In my opinion, it’s advisable to first check the alignment of the equipment, while also paying attention to the bearing temperature and observing how it compares to normal operating conditions. If the temperature rises significantly, it is recommended to inspect the bearings
This is the fresh air unit; this is the condition during the trial operation.
Your “D-type drive” is probably a belt drive; the high axial vibration is caused by poor alignment of the pulleys, so it’s necessary to check the parallelism of the two pulleys.
Can frequency spectrum analysis be used? There must be a corresponding reason for that
Spectral analysis was performed: 1X peak value, 2X 1/5 peak value, and 1/6 peak waves between 0.2~0.8X
Since the peak value at the first harmonic is high, it is necessary to check the alignment of the impeller’s flow channels or for any abnormalities in the inlet pressure and flow rate. I don’t know the application scenario of your fan. If the operating parameters and usage conditions can be detailed, it will make it easier for everyone to analyze!
It is in trial operation in the production workshop; no pipelines have been connected and it has not yet been delivered to the customer
It is recommended to check the axial clearance of the bearing! Don’t know the fan’s model and manufacturer?
Is it belt-driven? It is recommended to check alignment first
This is mainly related to manufacturing and assembly: one is the gap between the air inlet and the impeller (including radial and axial gaps)； Secondly, the selection of bearing type and the adjustment of clearance must be appropriate for the load ； Third, it is essential to ensure good lubrication and cooling ； Fourth, it is necessary to avoid the effects of additional forces and vibration sources. This post was last edited by xhyczz on 2009-2-27 14:35.]
The main problem might be the balance of the impeller; it should undergo dynamic and static balance tests. Additionally, during assembly, there could be issues with the bearings
Check the alignment of the bearings and coupling.
It is sufficient to mainly check the impeller balance issue.
Type D transmission is a coupling-driven system. There are many reasons for fan vibration; one should start by examining the overall aspects, such as the installation of the coupling, the levelness and stability of the fan foundation, the coaxiality of the motor shaft and the drive shaft, the assembly of the bearings on the drive shaft, the coaxiality and perpendicularity between the drive shaft and the impeller, the gap between the air inlet and the impeller, and most importantly, the static and dynamic balance tests of the impeller.
If it is a Roots blower, check the gap between the two impellers as well as the gap between the impellers and the wall panels. It’s hard to say about other fans.
The horizontal and vertical vibrations are not significant, while the axial movement is considerable (accompanied by screeching sounds). According to the spectrum analysis, the secondary values increase, and harmonics are present; side frequencies are generated on either side of these harmonics. It is preliminarily determined that the main cause is an increased bearing clearance, with wear at the shaft’s bearing locations being another possible factor
1 Check the shaft runout. 2 Verify whether the strength of the support base is sufficient. 3. Check the shaft end torque. 4. Check the shaft runout. Finally, perform no further dynamic balance checks