Quality rolling element bearing greases function over a wide temperature range; offer thermoox idative stability and low volatility; and have base oils that retain the viscosity needed to provide an adequate lubricant film throughout a specified range of operating temperatures, speeds and loads. Using these general characteristics as the yardstick for selecting a lubricant will help ensure high performance and long life for rolling element bearing applications.

Enhancing grease performance

Greases are formulated by combining a base oil with 
a thickening agent. They lubricate rolling bearings by bleeding a small amount of oil out of the “reservoir” of the grease thickener and into the raceway. The oil provides the elastohydrodynamic lubricating film needed to reduce friction and wear. Greases can also serve as effective seals to protect bearings from contaminants and moisture. For greater loads, especially where vibration or shock loading is likely, special anti-wear additives can improve grease performance. Likewise, special thickeners and additive packages can augment a grease’s natural resistance to wash-out by water or salt-water spray. Thickeners can also be processed to reduce the noise-generating characteristics of a grease. Finally, other additives can tailor a grease to specific application needs: PTFE for low temperature torque, molybdenum disulfide for high loads, special additives to promote electrical conductivity, and specific chemistry for low vapor pressure applications.

Ultrafiltration services

Nye will ultrafilter any of its oils and greases, and recommends this service for precision bearing applications to extend bearing life. Standards of cleanliness are clearly defined by the US government for both oil and grease. MIL-STD-1246 includes five cleanliness levels for oil: 50, 25, 10, 5, and 1, where each number refers to the largest particle (in microns) allowed in an oil. There are three cleanliness levels for grease. Unfiltered grease can contain particles larger than 75 microns. Filtered or “clean grease” cannot have any particles larger than 75 microns, and there must be less than 1,000 particles per cubic centimeter between 24 and 74 microns in size (MIL-G-81322, Aircraft Grease). Ultrafiltered or “ultraclean grease” must not have any particles larger than 35 microns, nor may it have more than 1000 particles per cubic centimeter between 10 and 34 microns in size (MIL-G-81937, Ultraclean Instrument Grease). Nye offers ultrafiltration services in a Class 100 environment for our own oils or greases — and for those of other manufacturers, which continues to be a sizable portion of our operations.

Selecting the right lubricant for your application

Below is a partial list of Nye lubricants for rolling element bearings. Additional oils and greases are available to meet a wide range of application requirements. For technical specifications, evaluation samples, questions about any of our products, or to discuss a lubricant for your application — call us or send us an email to our branch office nearest to you.

Greases for Rolling Element Bearings