A powder or bonded film that separates surfaces where oil cannot survive or stay put: very high or low temperatures, vacuum, extreme loads, slow oscillation or dusty environments. Graphite and molybdenum disulfide work through layered crystals whose planes shear easily, graphite needing a little moisture and moly working best dry. PTFE slides on its own low surface energy. They are used as bonded dry-film coatings, anti-seize pastes and additives in greases for slow, shock-loaded joints.
Kiln car bearings are too hot for grease, we run a graphite solid lubricant on those.
Also heard as
- dry lubricant
- dry film lubricant
Related terms
Moly
Shop name for molybdenum disulfide, the black solid lubricant, or for any grease that contains it.
Boundary lubrication
Regime where surfaces touch through the oil and protection comes from chemical surface films, not fluid pressure.
EP
Extreme pressure: additives or oils that react with metal under heavy load to prevent welding and scuffing.
Grease
Semi-solid lubricant made of oil held in a thickener sponge, usually with additives.