Why a checklist
A bearing rarely fails without warning. Temperature creeps up, a hum turns to a growl, grease appears where it should not, or vibration readings rise. A checklist gives operators and technicians a short, repeatable way to notice those changes. It also gives the plant a record to compare against, which is more useful than the memory of one person.
The lists below are general starting points based on common practice. Set intervals and limits for each machine according to the manufacturer manual, the bearing supplier data and your own history, and adjust after a few months of records.
Daily and shift checks (operators)
- Listen. Walk the line and notice new noises: grinding, rumbling, squealing, clicking. A change matters more than the absolute sound.
- Feel and look. Check for grease or oil leaks, discolouration around seals, and loose guards or covers. Use a temperature label or non-contact thermometer where available. Do not touch rotating parts or hot surfaces.
- Compare. Compare similar machines side by side. A bearing that is clearly hotter or louder than its twin deserves attention.
- Report. Log anything unusual with the machine ID and time, even if the machine keeps running.
Weekly and monthly checks (technicians)
| Check | Method | What to look for |
|---|---|---|
| Bearing temperature | Handheld probe or infrared thermometer, same point and load each time | Steady value; rising trend or a jump compared with the baseline |
| Vibration | Handheld meter or portable analyser | Rising overall level, new peaks at bearing frequencies |
| Noise | Listening rod, stethoscope or ultrasonic detector | Roughness, intermittent clicks, hiss from dry bearings |
| Lubrication | Grease or oil level, quantity added, grease condition at the relief path | Dark, dry or contaminated grease; low oil level |
| Seals and housings | Visual inspection | Worn lips, cracks, water ingress, loose bolts |
| Belts, chains and couplings | Tension and alignment check | Overtight belts load bearings; misalignment adds stress |
| Environment | Look at dust, water, heat sources | Build-up of dirt near seals, nearby steam or hot surfaces |
Temperature thresholds depend on the machine, so set alarm levels from your own baseline readings and the grease and bearing limits, for example a rise over normal that triggers inspection. A rapid, sudden rise usually means a problem now; a slow rise points to wear, grease ageing or contamination. Heat causes are listed in bearing overheating causes.
Lubrication tasks
- Keep a list of every lubrication point with the grease or oil type, quantity and interval. Methods for setting intervals are in bearing relubrication intervals.
- Use clean tools and clearly labelled grease guns, one per grease type.
- Wipe fittings before and after greasing. Dirt on the fitting goes straight into the bearing.
- Add the planned quantity with the machine running, if safe and allowed, so fresh grease distributes. Remove the drain plug if the design requires it.
- Record date, point and quantity. Check oil levels and change oil according to analysis or schedule.
Annual and shutdown checks
- Check shaft and housing alignment, soft foot, and coupling condition.
- Inspect housings, mounting bolts, locking collars, nuts and washers for looseness.
- Take grease or oil samples from critical points for analysis if the plant has the resources.
- Check for electrical current passing through motor bearings, particularly on drives with variable-speed controllers. Shaft grounding or insulated bearings may be needed; see electrical erosion in bearings.
- Review the year's records: temperature, vibration, grease use and replacements. Adjust intervals and alarm levels.
- Check spare parts stock and storage conditions, as described in bearing storage and shelf life.
When a bearing is replaced
Treat every removal as a chance to learn. Pull the bearing carefully (see how to remove a bearing), photograph it, keep the grease, and note hours in service. Inspect the shaft and housing seats and correct wear. Fit the new bearing with the right tools, fit tolerances and clearance (see how to install a bearing). After start-up, record temperature and vibration as the new baseline. Replacing a bearing without finding the cause of the failure is the surest way to see it again.
Setting baselines and alarm levels
Numbers only mean something against a reference. When a machine is new, or after a bearing change, take readings at the same points under the same load and speed: housing temperature, overall vibration velocity and, if you have the tool, an ultrasonic level. These become the baseline. Set a first alert at a modest rise above the baseline, and a second, higher level that calls for planned action. Standard severity charts for vibration, published for broad machine classes, can help in the beginning, but your own trend is the better judge over time.
Keep conditions comparable. A reading taken during a cold start, at partial load, or right after relubrication differs from one at steady state. Write the operating state on the log sheet. Where many similar machines exist, such as a row of fans or conveyor drives, compare them with each other and investigate the outliers first. This is a low-cost way to prioritise limited technician time.
Review the thresholds quarterly. If alarms trigger without findings, widen the limit slightly; if failures occur without prior alarms, tighten it or add another measurement type such as ultrasound for slow-speed bearings. The aim is a short list of real problems, not a long list of false alarms that people learn to ignore.
Records and spares planning
Keep one record per critical machine: bearing designations at each position, suffixes, lubricant, fits, replacement dates and any findings. That record shortens ordering time because the correct designation, with clearance and seal suffixes, is on hand. Hold spares for critical positions, rotate stock and check packaging.
For buyers who supply maintenance teams, a good practice is to agree on a standard list of bearings, greases and accessories per customer, so that orders are quick and consistent. The desk can quote such lists from the product catalogue, and the partner plants confirm the typical reference MOQ and lead time in writing for each program. Send your list through the quote form.
Safety reminder
Lock out and tag out machines before any hands-on work, wear suitable protection, and never reach into guarded areas. Measuring a running machine should be done with approved tools from a safe position. A checklist is a support for judgement, not a replacement for the plant safety procedures.