Detecting Wire Roll Bearing Defects in a Paper Machine

Wire Roll Drive Side Bearing Impacting from BPO (Ball Pass Outer Raceway) in the load zone, but also thrust region.

Paper Machine Wire Turning Roll on the Drive Side.  Readings are taken every month, or less frequently.  No noticeable increase in Demodulation over the course of the failure, with the majority of the peaks in demod at 1x and harmonics.  Though amplitude for the 420RPM Roll bearings is under 2gs in the time waveform, and less than .07gs in the FFT (Spectrum) the number of sidebands are significant and should be taken into consideration when determining severity.  In this case the roll bearing should be replaced within the next couple of weeks, and monitored every other day if not daily until the bearing is replaced.

Replacing the bearing will of course be at the discretion of the management and the distance before the next shut down.

Waterfall of the FFT over the last few months on the left shows the progression in bearing damage from Outer Raceway defects with sidebands at higher orders at 1xRPM indicating significant damage being excited constantly as well as modulating at 1xRPM as the shaft thrusts back and forth.

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The spectrum shows the harmonics with the 1x Sidebands

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The waveform here shows the energy increasing over the last few months, but mostly over the last month.  There are two modulations to notice, one is the modulation at 1xRPM and the other is the modulation at BPO (higher frequency closely spaced peaks).

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IMAGE 4 WRR008 Note that the Tending Side of the roll shows an increase at BPO as well.  So the question is, do we replace the entire roll, or just the drive side bearing?

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IMAGE 5 WRR009A look at the demodulated readings of this bearing give us our answer.  Even though the vibration at bearing fault frequencies are evident on the TS bearing, the demodulation shows very little energy, and no impacting.  This is good news as it means the TS (Tending Side) bearing is ok.  Demodulation readings are different as the vibration is all very high frequency and vibration at high frequencies does not travel very well.

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