Catch Failure Before It Catches You
Bearing failures rarely happen without warning. The signs are there — you just need to know what to look for. Here are the five most common indicators that a bearing is approaching end of life.
1. Rising Vibration Levels
If you're running condition monitoring, a steadily rising vibration trend on a bearing position is the earliest and most reliable warning sign. Look for an increase in the high-frequency envelope ( SKF's SKF Enlight and similar tools excel here). A sudden step-change is more concerning than a gradual rise.
2. Grease Leaking Past the Seals
When grease starts escaping past the seals or caking around the housing, the seal has degraded. This means two things: the lubricant is being lost, and contaminants are getting in. Both accelerate wear.
3. Audible Changes
A healthy bearing runs quiet. Any new sound is worth investigating:
- High-pitched squeal — inadequate lubrication
- Gritty, irregular rumble — contamination or brinelling
- Sharp knock under load — cage damage or internal clearance loss
- Continuous whine — misalignment or preload issue
4. Temperature Spike
A bearing running more than 20°C above its baseline is in trouble. Above 80–90°C, the lubricant is breaking down and the steel is losing hardness. If you can't hold the housing for more than 2–3 seconds, shut down and investigate.
5. Discoloured or Burnt-Smelling Lubricant
When you withdraw a grease sample, it should be the same colour and consistency as when it went in. Dark, gritty or burnt-smelling grease has oxidised. Milky grease means water ingress. Either way, the lubricant has lost its protective film strength.
What to Do When You See These Signs
Don't wait. If you spot any of these warning signs, schedule an inspection. In most cases, a planned replacement during a maintenance window costs a fraction of an unplanned failure mid-shift.
