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WWST

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Reply with quote  #1 
I just installed a wireless monitoring system on a conveyor drive system   (100 sensors in 2 days, about 1000 more later..). Most of you probably wouldn't bother with a motor this small and so easy to take out, but they measure downtime in minutes here, and the consequences of downtime are holding up UPS/FEDEX trucks/planes or missing a shipment deadline.

The motor is 6 months old, runs on a VFD (like 100s or others in these warehouses) and has an audible whining sound. I thought it might be a noisy VFD Drive interacting with the frame of the motor and fan cover, I can dampen it a little with my hands. Fault frequencies for 6205 BPFO are pretty close in the high end.
TWF 31175.jpg

FFT/TWF looks more bearing BPFO than drive to me. Opinions? This sensor goes up to 2500 Hertz. We have a new wireless sensor in test that will be much higher (-3dB 11 kHz, resonance at 21 kHz)

31175 FFT BPFO.jpg  31175 motor gearbox.jpg

Walt Strong

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Reply with quote  #2 
The dominant frequency is in middle of audible range. Looks like two sets of sidebands around the dominant frequency near 1875 Hz. The low set might be shaft speed and the high set might be 2x line frequency. It would be a real shame and expense to shutdown with a false bearing fault diagnosis! Might look at spectra at other speeds.

Walt
Dave Reynolds

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Reply with quote  #3 
Suggest you compare similar motor/gbxs to each other. If you have a bunch of these motor/gbx assemblies that run similar speeds, set your units/scales the same on spectrum and waveform and paste into a document. Then compare this data to similar units within your facility. The G values in TWF are slightly high but you also have energy from a vfd and a gearbox in this data.....

Understand these are critical, but you can adjust the frequency of data collection on this unit to quickly collect a lot of data and you can then set very accurate statistical alarms for vibration and temperature

Once you find a "bad one" make sure to investigate the bearings/gbx to see if you should have waited to make repairs or should have repaired sooner

Dave Reynolds
Midlands Reliability & Consulting LLC
Walt Strong

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Reply with quote  #4 

Dave made a good point about comparing similar machines running at the same speed, if possible. I would also be concerned about whether vibrations are from the machine itself or something else, possibly the conveyor belt or chain drive or items on the conveyor. Instantaneous alarms can be a good thing, but that verifying a real problem is present also needs to be handled expeditiously to prevent false positives or false negatives that cause an expensive shutdown of production.

 

Walt

WWST

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Reply with quote  #5 
Motor went to the local repair shop this morning. Preliminary list of as found abnormalities:
  • drive end bearing loose in housing
  • fluting in load zone on both bearings
Happy customer wants another 3,000 wireless sensors at another facility.

Pictures to follow...
WWST

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Reply with quote  #6 
TEMP BEFORE AFTER.jpg  TWF after.jpg 
WWST

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Posts: 86
Reply with quote  #7 
Fluting in load zone. Bearing was a bit loose in the housing too. Frosting on the balls too (accidental porn?).

Attached Images
jpeg bearing fluting.jpg (92.12 KB, 13 views)
jpeg 5220.jpg (97.79 KB, 12 views)

Walt Strong

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Reply with quote  #8 
Bill,

Good job with fault detection. Fantastic product order!

Walt
WWST

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Reply with quote  #9 
Thanks Walt. If this entire project is approved, we will be the largest supplier of wireless vibration sensors in the world. What a ride!
Barry

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Reply with quote  #10 
So Bill are we to assume these faults were missed by other analysts or was this something new for your coustemer. IMHA you should have started this with a vendor warning (rusty may edit or delete this) because it was not for help but to market your products.
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Barry
WWST

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Reply with quote  #11 
Barry take a deep breath.
This is definitely something new for our customer they have been using a walk-around ultrasonic gun to try to find defects with little success. With the installation of Wireless with temperature and vibration in two channels they are finding many defects immediately, that were completely missed by ultrasonic walk around program.

This was meant as interesting and different for what most of us do in the world of vibration. Not very good marketing since I didn't talk about the specs of the product the name of the product or where to buy the product.

Sorry if you took offense for some reason. Just trying to add to the discussion of this forum.
Walt Strong

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Reply with quote  #12 
This Forum needs a good problem description, good discussion, and good feedback about findings and corrective actions. The OP and this thread provided an opportunity for us to discuss a real problem without the commercial/marketing aspects of a product or service. Seriously Barry why would you want to delete or edit this information?

Walt
Barry

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Reply with quote  #13 
Edit or delete my post Walt not anything that was posted by you guys.
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Barry
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