Ball Mill - Loose Bearing Housing on a High Voltage Motor

AVOIDED CATASTROPHIC BREAKDOWN!
Last week our diagnostic team avoided a catastrophic breakdown for one of our clients, at a production critical machine.
In my almost 30 years of experience in the field of condition monitoring, I believe this is one of the most important failure we detected and acted upon. Failure was detected - and repaired - with no stop in production.

Attached is a summary of the case study. As in most case studies there is more information to the case, but this is a good summary.
When it comes to potential savings I generally hate to put numbers, but in this case the breakdown with a loose bearing housing on a high voltage motor, would be very catastrophic and potentially cause fire.

Summary:
All production critical machines are continuously monitored by the Vibguard vibration system.

Background:
• In Q2 2023 the factory was stopped for major maintenance.
• The motors for the ball mill was sent to workshop for overhaul due to winding conditions.
• Factory back in operation in June 2023.

Recommendation
- client was informed about the severity by phone Monday morning 11 sept.
- By studying the motor drawing, we suspect the bearing housing to be loose. Please inspect.
- Motor should be stopped to avoid breakdown

Client followed recommendation and went out to inspect the motor immediately.
Finding:
• All 4 bolts loose on the bearing housing. Pictures at next page.
Action:
• Tighten the loose bolts.
Result:
Motor status is back to acceptable, you can continue to operate the motor.

Savings:
If breakdown:
✓ Production downtime of ??-days.
✓ Repair of motor or new motor. ?

Saved by online monitoring:
✓ Tightening the bolts. (30 minutes by mechanic. No extra cost)

A mild estimation is minum 1 million NOK.
NOTE‘’’’’’’HUGHE POTENTIAL OF CATASTRPHICAL FAILURE’’’’:
If the bearing housing would come completely loose, the rotor of approx. 1 tonn would drop directly into the stator at a speed of 1500 RPM. These are High voltage motors (6000V) and this would be dramatic. In worst case this could cause fire.

Enjoy reading.

Btw; we could also be a part of your maintenance team. Just make contact and we discuss. This is our main service.

ball mill loose bearing housing