PROGNOST®-Predictor successfully detected misalignment in the input shaft bearing that progresses to imbalance within 15 minutes, allowing the extruder line to be successfully shutdown before additional damage occurred. The MAAG gearbox in service since 2013.

Pic 1: Gearbox showing oil residue on the side of the housing

 

Pic 2: PROGNOST®-Predictor trend before event

 

Pic 3: Trend just before shutdown

 

Immediate actions taken

  • Operations brought extruder to a safe state
  • Proper people were called to review all information and data to assist with a path forward
  • Vibration group checked the input shaft
  • It was determined that input shaft axial movement was out of tolerance
  • Machine was kept down until spare gearbox and motor could be installed

Root Cause

Pic 4: Input shaft bearing outer race spinning within the bearing housing

Contributing causes

  • Motor bearing fits were at the maximum acceptable limits
  • Motor was sent out and had the bearing fits re-machined to give longer life after the rebuild
  • The Motor bearings showed normal wear on the race and virtually no wear on the rollers
  • Gearbox has been running at max load

Recommended corrective actions

  • Check all bearing fits and record all measurements
  • Compare current measurements with measurements from the previous rebuild to help determine if the maximum allowable tolerances need to be changed to help reduce this type of failure
  • To ensure gearbox is rebuilt to OEM specifications

Total Cost 

$1,495,724.88 for Maintenance and Loss of Production