Bearing Lubrication Best Practices for Longer Service Life
Grease vs oil lubrication, re-lubrication intervals and common over-greasing mistakes.
Poor lubrication is among the most common reasons bearings wear out early. Using the right lubricant in the right amount at the right interval costs little and often decides how long a bearing lasts.
Grease or oil: how to choose
Grease is the usual choice for most electric motors, fans, pumps and general machinery. It stays in the bearing, helps keep out contamination and needs less equipment. Oil is chosen for high speeds, high temperatures, or where the bearing shares a lubricant system with gears, as in a gearbox.
Choosing a grease
Greases differ in base oil viscosity, thickener type and additives. The thickener types are not all compatible with each other, so mixing two different greases can soften or harden the mix. When you change grease type, clean out the old grease first or check compatibility with the supplier.
- Match the base oil viscosity to speed and load: lower viscosity for high speed, higher for heavy load and slow speed.
- Check the grease's temperature range against the bearing's operating temperature.
- Use a grease designed for wet or dusty conditions if the plant needs it.
How much grease
A bearing is not meant to be full of grease. Too much grease causes churning, which raises temperature and can push grease past the seal. A common rule is to fill the bearing and then about one third to one half of the free space in the housing, depending on speed. Follow the machine manufacturer's instruction where one exists.
Re-lubrication intervals
The right interval depends on speed, temperature, bearing size and environment. Hot, wet, dirty or high-speed bearings need re-greasing more often. Bearing manufacturers publish interval charts and calculators; use these for critical equipment rather than a single plant-wide schedule.
Common mistakes
Over-greasing, mixing incompatible greases, using one grease gun for several grades, and greasing without cleaning the nipple first are all common causes of contamination and early failure.
Key Takeaways
- Use the grease type specified for the machine and speed.
- Do not over-fill; excess grease raises temperature.
- Clean the grease nipple and use dedicated guns for each grade.
- Set intervals by operating conditions, not just by the calendar.
This article is general guidance. For a recommendation for your own application, contact our engineering team. View our bearing range →