Selecting a suitable grease

Performance and operating conditionsBearing type and arrangementBearing sizeLubricationOperating temperature and speedBearing specificationBearing executionSealing, mounting and dismounting

Selecting a suitable SKF grease

The assortment of SKF greases for rolling bearings provides adequate choice for most application requirements. These greases have been developed based on the latest knowledge of rolling bearing lubrication and their quality is continuously monitored.
Using LubeSelect and selection rules
SKF LubeSelect is an online tool that lists SKF greases that fulfil the demands of your specified operating conditions. The analysis performed by the tool is based on generalized selection rules that have been carefully developed by SKF lubrication experts.

The same selection rules are used in the SKF bearing grease selection chart [PDF], where the speed, temperature and load range are used as the primary operating parameters for selecting a suitable grease.

Temperature, speed, and load ranges for grease selection

The terms used to specify the ranges of temperature, speed and load, for grease lubricated bearings, are defined in table 1, table 2 and table 3.

Consistency, NLGI

Consistency is a measure of the stiffness of the grease. Classification of greases by consistency is in accordance with the National Lubricating Grease Institute (NLGI), ISO 2137. Greases with a metallic soap thickener and a consistency grade of 1, 2 or 3 (soft to stiff) on the NLGI scale are typically used for rolling bearings. The most commonly used greases have a consistency of grade 2.

Mechanical stability

During rotation of a bearing, the grease is mechanically worked and a change in consistency may result. This property is known as the mechanical stability of the grease and is measured in standardized tests, ASTM D217 and/or ASTM D1831. Greases that soften may leak from the bearing cavity. Those that stiffen may restrict bearing rotation or limit oil bleeding. The mechanical stability should not change drastically if operation is within the specified temperature range of the grease. 

Corrosion protection

In applications where water or condensation is present, the corrosion inhibiting properties of the grease are very important. The corrosion inhibiting ability is determined by the properties of the rust inhibitor additive and/or the thickener type. The performance is measured using the EMCOR test, ISO 11007. For applications where water or condensation is present, the rating should be 0-0.

The most important technical specifications for SKF greases are provided in Technical specifications for SKF greases [PDF].

The SKF traffic light concept for grease temperature performance
The temperature range over which a grease can be used depends mainly on the type of base oil, thickener and additives. The relevant temperature limits are schematically illustrated in diagram 1 in the form of a double traffic light, with additional details provided in diagram 2.
  • The low temperature limit (LTL) is determined by the low temperature frictional torque test according to ASTM D1478 or IP 186. The