Bearing Failures Resolved Through Condition Monitoring

  • Company: HJ Enthoven & Sons
  • Industry: Process & Manufacturing
  • Services: Vibration Analysis, Oil Analysis, Cloud-based Reporting
  • Location: United Kingdom
  • Cost-Saving: £4,555

The Overview

We investigated multiple failures on a Drive End (DE) bearing on a Gypsum Plant Booster fan unit. Through further investigation, it was identified that potentially three different types of grease had been put into the bearing. All grease was removed and replaced with just one type, preventing unexpected bearing failures estimated at £4,555 per failure.

The Situation

After experiencing two failures in quick succession on a Drive End (DE) bearing, H J Enthoven & Sons contacted us to request an inspection on their Gypsum Plant Booster fan unit.

The Challenges

After the initial failure, maintenance staff at HJ Enthoven & Sons identified damage on the fan shaft and replaced the fan and DE bearing. Following this work, an increase in temperature on the same DE bearing was noted preceded by a second failure. The bearing was replaced along with the motor unit and coupling, but the root cause of the DE bearing failure couldn’t be identified.

The Solution

We used vibration and stresswave analysis to monitor the motor unit and fan bearings, in order to identify bearing issues/defects, insecurity, imbalance and/or misalignment. Overall, the running speed vibration amplitudes across the unit gave no concerns to indicate any fan imbalance or coupling misalignment.

The Results

The initial set of data collected showed concerning levels of stresswave activity for both fan bearings with prominent cage defect frequencies seen at the DE bearing.

Ours engineers suspected the cause of this was that initial packing grease had dispersed from the bearing following several hours of running. Additional grease was added to the unit, however this only temporarily reduced readings.

Figure 1: Solidification on non-drive end bearing

Oil around the joint between the bearing housing halves of the non-drive end NDE fan bearing was identified, which indicated a potential separation of oil and soap of the grease. Discussions with site engineers identified potentially three different types of grease had been put into the bearing.

At the recommendation of one of our reliability engineers, the bearing housings were opened and site engineers found solidification of the greases due to incompatible grease properties.

Figure 2: Our reliability engineer collecting vibration data

All grease was removed and replaced with just one type. Additional lubrication was added after approximately 12 hours of operation (as per manufacturers recommendations) as initial packing grease once again dispersed from the bearing following start up.

The bearing temperature has remained stable and no issues with fan operation have been reported.