Grease Lubrication for Precision Bearings

Proper lubrication is one of the most critical factors in achieving maximum bearing performance and service life. Choosing the right grease, understanding the quantity of grease needed, and ensuring speed and temperature compatibility are all essential to preventing premature bearing failure, but this is where our engineering expertise is here to help. The following guidelines highlight several key considerations when selecting and applying grease for precision bearings.

Hand with blue gloves inserting grease into metal bearing

Selecting The Right Bearing Grese Type

Temperature Range

The temperature range of your application is a significant data point in choosing the correct bearing grease. High temperature greases can be very sticky and difficult to work with, let alone costly. Therefore, if the application is only going to see ambient temperatures, it is much more optimal to go with a standard grease rather than something special and expensive when it is not needed.

Note: While high temperature greases are expensive, having a standard grease in an application with higher temperatures can cause bearing failure. Grease life drops in half for every 10°C temperature increase. Additionally, the viscosity goes down, and the lubrication can lose the oil film layer which would cause metal to metal contact and rapidly decrease the life of the bearing.

There are thousands of types of bearing greases for all sorts of special applications (food-grade, vacuum applications, low temps, high temps, etc.). If a specific application requires a specialized grease, GMN has the supplier relationships and expertise to procure the right solution as needed. Our team is here to help you find the right solution for your application. Contact us to get started.

Grease Speedability and n*dm

Another key factor in bearing grease selection is the speedability (or speed capability) of the grease vs. the RPM or RPM range of the application. Bearing grease manufacturers publish a factor called n*d_m. This is the RPM of the application times the diameter of the center of the balls. This factor prevents grease shear, or separation, from being too high of speed for that particular grease.

Staying below this rating for any type of grease is crucial to achieving long application life. Operating above the specified n*d_m factor of the grease will lead to shear/separation. As the base oil is expelled from the bearing, only the thickener remains, causing lubrication failure and significantly shortening bearing service life.

Explore more about types of bearing lubricants.

Bearing Grease Fill Percentage

The quantity of grease can greatly affect the running performance of any bearing. For precision ball bearings a grease fill of 20-30% would be considered standard. GMN Bearing USA uses 25% as standard. Most manufacturers have a tolerance of +/-5% on this fill and it is measured by percent of open space within the bearing.

The most accurate way to add grease to a bearing is with a precise scale converting the open space percentage to weight via the grease’s density. This information can be found in our Precision Ball Bearing Catalog, and our team of bearing experts are always available for your technical questions.

GMN’s Expertise

It is strongly recommended that GMN greases bearings for you prior to delivery. There are multiple reasons for this, as listed below, but the guiding principle is the same; preventing bearing failure.

Cleanliness: Contamination in a bearing during the lubrication process can greatly reduce overall bearing and application life. GMN has special equipment and training to ensure the utmost cleanliness during the greasing process.
Accurate Grease Amount: Lubrication must be precise to prevent bearing failure. If there is too little or too much grease, the bearing may run hot and prematurely fail.
Proper Application Technique: It’s crucial for grease to be applied in the correct location within the bearing using proper greasing tools. These tools aid in injecting the grease into the right spots, and when the bearing initially spins, the grease migrates to the proper location(s) within the bearing itself.

These are practices that have been learned and perfected over many years here at GMN Bearing USA and are done successfully on a daily basis by technical experts.

Talk to an Engineer

Every application has unique lubrication requirements, and choosing the right grease can make a significant difference in bearing life and performance. GMN engineers are experts at identifying the best bearing lubrication for a range of specific needs.

Contact us today to discuss your application requirements!