A failure in which the lubricant film collapses under high load, speed and sliding, so the metal surfaces bond and tear, leaving rough, dull bands of radial streaks in the sliding direction. It concentrates at tips and roots, where sliding is highest, and can happen within minutes of overload or lube failure. Contributing factors are flash temperature, oil viscosity and additives, surface finish and missing tip relief.
Scuffing at the tips of every tooth, radial streaks, that's oil film breakdown, not fatigue, what did they fill it with?
Scuffing is a lubrication failure, so check oil type, temperature and the first hours of running before blaming the steel.
Also heard as
- scoring
Related terms
Flash temperature
The brief spike in surface temperature where teeth slide over each other under load, used to predict scuffing.
Hypoid gear
A spiral-bevel-like gear pair with the pinion axis offset from the gear axis, standard in vehicle drive axles.
Tip relief
A slight removal of material near the tooth tip so each tooth enters mesh smoothly under load.
Lambda ratio
Oil film thickness divided by combined surface roughness, showing how well the lubricant separates the teeth.