Hey there, We recently replaced the bearings on a closed coupled 5.5 kW motor that had been running smoothly with a maximum vibration of 3.2 mm/sec. However, after the change, the vibration levels have spiked to 50 mm/sec in the axial direction, 45 mm/sec vertically, and 28 mm/sec horizontally. This sudden increase in vibration is concerning. The dominant peaks in the spectrum analysis are at 1x and 2x in the axial, horizontal, and vertical directions. Can anyone provide insight into why these vibrations have escalated so drastically? Your expertise in solving this issue would be greatly appreciated.
Is the motor connected to a fan on the same shaft or a pump with a close coupling? - Walt
In fact, this is a blower where the motor is directly connected to the fan impeller, operating at a speed of 2920 RPM.
Vidhya, did you notice any sudden differences in performance after replacing the bearings? When replacing the inboard bearing, is it necessary to remove the blower impeller or any other components? While this may not be relevant to your situation, abrupt changes can sometimes be due to imbalance, such as a piece of metal breaking off. It is important to consider the possibility that the 'new' bearings could be counterfeit.
Narayan, the blower impeller has been removed to replace the inboard bearing. After replacing the bearings, I checked the static balance of the blower and it was satisfactory. However, there seems to be fluctuating vibration levels, sometimes reaching 50 and other times dropping to 13. I will investigate the possibility of spurious bearings, but the trend persists even after changing the motor and taking new readings.
Including a cross-sectional drawing can enhance understanding of the details for readers. It seems that the readings spiked right after the bearing change, ruling out metal fragments as a potential cause based on static balance results with changes from 50 to 13. Possible reasons could include improper impeller mounting and faulty bearings, but without necessary data, we can only speculate. According to your notes, the blower continues to operate at excessively high vibration levels. At 2950 rpm, it would be advisable to halt operations and conduct a thorough inspection of the assembly.
From what you've described, it sounds like there could be a few different issues at play. The problem could potentially stem from a misalignment between the motor and the pump, incorrect installation of the bearing, or a bearing defect right out of the box. A faulty installation of the coupling could also be causing an imbalance. I suggest a thorough check on the alignment and reinstallation process of the bearings. For a more accurate diagnosis, it would be quite helpful if you could provide more information about the type of coupling and the tasks the motor is usually responsible for.
Hey there, sorry to hear about the sudden spike in vibration levels after replacing the bearings on the motor. The significant increase in vibration could be due to various factors such as misalignment, improper bearing installation, unbalanced rotor, or resonance issues. I recommend checking for these potential causes and ensuring proper installation and alignment to help mitigate the vibration problem. Good luck with resolving the issue!
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Answer: - The sudden increase in vibration levels post bearing replacement could be due to various reasons such as improper bearing installation, misalignment, unbalanced rotor, or other mechanical issues that need to be addressed.
Answer: - The dominant peaks at 1x and 2x in the spectrum analysis of the motor vibrations could indicate issues related to rotor unbalance, misalignment, bearing defects, or resonance within the system.
Answer: - To address the escalated vibrations, thorough diagnostics and analysis are required. Potential solutions may include checking for proper alignment, ensuring balanced rotor, inspecting bearings, and investigating any resonance issues within the system.
Answer: - Troubleshooting steps may involve conducting a detailed inspection of the motor and its components, checking for proper installation of the replaced bearings, performing alignment checks, analyzing the spectrum for peaks, and taking corrective actions based on the findings to mitigate the vibration issue.
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