Lubricating of mechanisms for vacuum service

Abstract

Seizure of metal parts which occurs during sliding or rolling in a vacuum environment can be prevented by use of appropriate lubricants. Fluid lubricants, having low evaporation rates, dry solid film lubricants, soft, low shear strength metals, and composite materials are customarily used, but ion implanted metals and ceramics are available for extremely harsh environments. Bearings, bushings, gears, cams, guides and slides, solenoids, commutators, motor brushes, and sliprings can be lubricated to yield vacuum service lives comparable to those achieved in normal atmospheric pressure applications, or even longer due to the absence of O2 and H2O. The use of fluid and dry lubricants may require the incorporation of seals to prevent molecular or particulate contamination of test or production hardware within the vacuum system. The most important parameter to be considered in selecting the appropriate lubricant is the operating temperature, which drastically affects the evaporation and contamination rates. Fluid based lubricants are available having evaporation rates of 10−9 to 10−13 g cm−2 s−1 and metals, composites, and dry lubricants having 10−10–10−14 g cm−2 s−1 loss rates at room temperature.