Moly
Moly turns up in 2 fields: tribology, thermal spray. Here is what it means to the people in each one.
Moly in tribology
Shop name for molybdenum disulfide, the black solid lubricant, or for any grease that contains it.
Clipped form of molybdenum disulfide (MoS2), a gray-black layered mineral used as a solid lubricant. Moly grease, typically lithium or lithium complex with about 3 to 5 percent MoS2, is the go-to for chassis points, pins, bushings and splines, where slow, shock-loaded sliding keeps the film in boundary. It is usually kept out of high-speed rolling bearings, where the solids add little and can pile up in the load zone.
"Hit the bucket pins with the moly, the regular red grease won't hold under that pounding."
Moly in thermal spray
Shop name for sprayed molybdenum, a scuff-resistant coating for piston rings, synchro rings and bond coats.
Clipped name for molybdenum coatings, flame-sprayed from wire or plasma-sprayed from powder. Moly bonds well to clean steel, holds oil in its fine porosity and resists scuffing, so it is the classic coating for piston rings, synchronizer rings and shift forks, as well as a bond coat. It oxidizes readily above about 400 °C in air, which limits hot service.
"Synchro rings go through moly on the wire gun, eight passes, then off to the lathe."