Hydrodynamic bearings rely on a continuous oil film to separate the moving surfaces. Inadequate flow, unsuitable oil conditions or loss of film thickness can produce metal-to-metal contact, rapid heat generation and a wipe of the soft bearing lining.
What the Damage Looks Like
- Smooth directional smearing or displacement of whitemetal
- Polished contact followed by scoring, tearing or melted alloy
- Heat discolouration around the loaded or oil-exit region
- Wiped material accumulated at an edge or oil groove
Likely Contributing Factors
- Interrupted oil supply, low flow or low supply pressure
- Blocked feeds, restricted grooves, dirty filters or filter bypass
- Excessive oil inlet temperature or unsuitable viscosity
- Start-up, coast-down or turning without adequate lubrication
- Overload, loss of clearance, misalignment or excessive shaft movement
Diagnosis and Response
Move From Damage to Root Cause
What to Inspect
- Review pump, header, filter and alarm or trip records
- Confirm oil grade, inlet temperature, pressure and flow at the bearing
- Inspect galleries, grooves, jets and drain paths for restriction
- Check start-up, shutdown, post-lubrication and jacking-oil sequences
- Inspect the shaft, bearing clearance, alignment and evidence of overload
Corrective Actions to Consider
- Restore and verify oil delivery through the complete circuit
- Clean contaminated galleries and replace or assess filters
- Correct oil viscosity, inlet temperature and cooling performance
- Verify protective trips, backup supply and lubrication sequences
- Resolve clearance, alignment or load conditions that reduced film thickness
Repair or Replace?
Minor superficial contact may be assessable, but smeared or heat-damaged lining normally requires re-lining. The shaft or thrust collar must also be inspected because a repaired bearing will remain at risk if the mating surface is scored, distorted or thermally damaged.
Diagnosis Note
Wiping describes the damage appearance, not always the initiating event. Oil starvation, overload, misalignment and high temperature can produce similar or combined evidence, so the lubrication system and machine data must be reviewed before assigning root cause.
Need an Engineering Assessment?
Send photographs, operating data and failure history for an initial review by Oiltech Bearings.