Frosting
Frosting turns up in 2 fields: tribology, gears. Here is what it means to the people in each one.
Frosting in tribology
Shop name for the dull, satin-gray sheen of early micropitting on gear teeth or bearing races.
Inspection slang for a frost-like matte area on a hardened surface where micropitting has started. Under a magnifier the frosted band resolves into countless tiny pits. On gears it often appears first in the dedendum of the pinion or near the tip, and it is worth photographing and trending because it can either stabilize or grow into macropitting.
"Couple of teeth have frosting below the pitch line, no pits yet, take photos and we'll look again next stop."
Frosting in gears
Shop word for the dull, frosted gray patches on gear teeth that turn out to be micropitting.
The field name for the matte, satin or frosted look of micropitted tooth flanks, often in a band near the root or tip. Light frosting may stabilize after running in, but frosting that spreads or deepens removes profile and leads to macropitting. Inspectors photograph it with consistent lighting so the area can be compared between inspections.
"Frosting on the high-speed pinion has spread halfway up the flank since the last borescope, that's not stabilizing."