Motor Bearing Cage Defect
Despite a serious defect in the bearing cage, overall vibration values are not considered critical. However, analysis confirms the motor bearing needs to be replaced.
This case study is unique because although there is an obvious and serious defect in the bearing cage, the overall vibration values of the spectrum & demodulation are not considered critical.
The vibration spectrum overall value is good 1.368mm/sec RMS, but the cage bearing defect frequency with its harmonics appears with low amplitudes in the spectrum.
- MNDE bearing demodulation recorded clear cage defect frequency with its
harmonics with overall value about 1g's.
- Also as illustrated in the above trend the demod overall value increased from 0.2g's
to 1g's.
- The twf recorded high pk to pk reached 10.8g's.
- The twf have a clear pattern of the cage frequency as rotated from load zone to low load zone.
- Also as illustrated in the above trend the twf overall value increased from 0.425g's to 2.15g's.
The vibration spectrum overall value is good 1.105mm/sec RMS, but the cage bearing defect frequency with its harmonics appears with low amplitudes in the spectrum
Analysis
After linking all the above spectrums, twf, and patterns, we confirm that the motor bearing shall be changed.
Additional Images
