A structured bearing maintenance programme reduces unplanned downtime by up to 70%. The goal is not to maximise how long a bearing runs, it is to ensure bearings are replaced before failure, at a time of your choosing. Here is a practical checklist for plant maintenance teams.
Daily Checks (Running Equipment)
- Listen for unusual noise, grinding, squealing, knocking
- Feel housing temperature by hand (back of hand, safe method). Anything that's too hot to touch comfortably (>60°C) needs investigation
- Look for grease leaking from housing seals
- Check for unusual vibration on shafts and frames
Weekly Checks
- Record bearing housing temperature with IR thermometer, compare to baseline
- Check grease nipples are clear (not blocked with hardened grease)
- Inspect for oil/grease contamination on belts and pulleys near bearing positions
- Check coupling alignment on direct-drive machines
Monthly Checks
- Relubricate bearings as per schedule (interval based on speed, size, temperature)
- Check oil level in oil-bath housings
- Vibration check with portable vibration meter if available
- Review temperature trend data for upward drift (early warning of failure)
Quarterly Checks
- Full lubrication change (oil-bath systems)
- Inspect seals for wear or damage
- Check belt tension and alignment (a loose belt overloads the bearing)
- Verify shaft alignment on coupled drives
- Inspect bearing housing for cracks, loose bolts
Annual / Major Shutdown
- Disassemble and inspect all critical drive bearings
- Measure internal clearance, if worn beyond limits, replace
- Replace bearings that have exceeded design life (L10 hours)
- Inspect shaft and housing fit surfaces for fretting, wear
- Update maintenance records with bearing designation, installation date, operating hours
Temperature Monitoring, Your Best Tool
| Temperature Reading | Status | Action |
|---|---|---|
| Ambient + 0, 30°C | Normal | Continue monitoring |
| Ambient + 30, 50°C | Elevated, investigate | Check lubrication, belt tension, alignment |
| Ambient + 50°C or above | Alarm | Stop machine, inspect bearing immediately |
| Any sudden temperature rise | Critical | Stop immediately regardless of absolute value |
Vibration Monitoring Basics
A simple handheld vibration meter (accelerometer) provides early warning of bearing defects. Baseline readings on a healthy machine give you the reference. Rising vibration amplitude, even before noise is audible, indicates developing bearing damage:
- Overall vibration increasing: check for imbalance, misalignment
- High-frequency spike: inner/outer race defect beginning
- Irregular broadband noise: contamination, lubrication starvation
When to Replace Rather Than Relubricate
Never "top up" a bearing that is already failing with more grease. Adding grease to a damaged bearing delays failure by days but does not fix the problem, and the eventual sudden failure will be more damaging to the machine.
Maintenance Records
For each critical bearing position, maintain a card or digital record with: bearing designation, manufacturer, date installed, running hours, relubrication dates, temperature readings, any abnormal observations. This data enables you to predict replacement dates and spot trends before they become failures.