On a roller conveyor, the bearings are the most numerous wear parts. A line with 400 rollers has 800 bearings, and one seized bearing can stop a product, mark a belt or overload the drive.
Key takeaways
- Listen, touch and measure; do not wait for a failure.
- Temperature rise is the most reliable early warning.
- Contamination is the main cause of bearing failure.
- Replace the roller, not just the bearing, if the shaft is worn.
Routine checks
Walk the conveyor monthly and listen for a dry or grinding sound. Touch the bearing housings with a thermal probe or an infrared thermometer; a bearing that is 10 °C hotter than its neighbours is suspect. Check for play by lifting the roller; a roller that moves vertically has a worn bearing or a worn shaft.
On a long conveyor, mark the rollers with a number so that a problem can be located and recorded.
Lubrication
Sealed bearings do not need lubrication, but the seal can be damaged. Open bearings need grease at the interval specified by the manufacturer, usually every 500–1,000 hours. Do not over-grease; excess grease can push out the seal and attract dirt.
In a washdown area, use a sealed stainless bearing or a polymer bearing. A standard bearing will fail quickly if water enters.
| Symptom | Likely cause | Action |
|---|---|---|
| Grinding noise | Dry or contaminated bearing | Replace |
| Housing hot | Overload or lack of lubrication | Check load, replace |
| Vertical play | Worn bearing or shaft | Replace roller |
| Current rise | Seized bearing | Find and replace |
| Rust | Water ingress | Replace with sealed stainless |
Replacement criteria
Replace the bearing when it is noisy, hot, rough or has play. If the roller shaft is worn at the bearing seat, replace the roller; a new bearing on a worn shaft will fail again. Check the roller for straightness; a bent roller will load the bearing and the belt.
Replace bearings in sets if the conveyor has been in service for a long time. A mix of new and worn bearings can change the roller height and affect the product.
Contamination control
Keep the conveyor clean. Dust, product residue and water are the main causes of bearing failure. In a dusty area, use a sealed bearing and wipe the roller ends during cleaning. In a washdown area, use a stainless sealed bearing and avoid high-pressure jets directed at the seal.
Do not use a steam cleaner on a standard bearing. The steam penetrates the seal and condenses inside.
Spare parts
Keep a stock of the most common roller and bearing sizes. The lead time for a special roller can be weeks; a stock of standard rollers can keep the line running. Record the roller specification (diameter, length, shaft, bearing) on the maintenance sheet.
Frequently asked questions
How long do roller bearings last?
It depends on load, speed and contamination. In a clean, light-duty conveyor, 5–10 years is possible. In a washdown or dusty area, 1–3 years is more typical.
Can I replace a bearing without removing the roller?
On some designs, yes, if the bearing is a press-fit in a removable housing. On most conveyor rollers, the roller must be removed.
Why do bearings fail on one side of the conveyor?
Usually because the conveyor is not level or the product is loaded to one side. Check the frame level and the load position.
For the complete maintenance schedule, see our daily inspection guide.
