In vacuum applications, such as equipment used in deep space, great care must be taken when choosing the bearing lubricant. In these conditions, greases can vaporise to unacceptable levels. This problem is commonly known as ‘outgassing’.
Special low volatility, perfluorinated greases with very low outgassing rates are designed to perform well under these conditions, meaning bearing lubrication isn’t depleted prematurely.
Similarly, you could use dry lubricants such as molybdenum disulphide or tungsten disulphide as a useful alternative as well as stainless steel bearings or ceramic bearings with no lubricant at all. Because these are burnished onto the bearing balls and raceways or applied by sputtering, the problems of outgassing are eliminated as solids can’t evaporate.
Got a question about using bearings in a vacuum — call us on +44 (0) 1993 842 555.