A finishing step, usually chemically accelerated vibratory finishing, that removes the peaks left by grinding and brings tooth surfaces to a roughness of about 0.1 micrometer Ra or lower without changing the profile. Smoother surfaces raise the lambda ratio, so the oil film separates the teeth better, reducing micropitting, wear, friction losses and running temperature. It is common on wind turbine, aerospace and racing gears.
Planet gears get superfinishing after grind, that's what fixed the micropitting on the last design.
Also heard as
- isotropic superfinishing
- ISF
- REM finishing
Related terms
Micropitting
Very fine surface fatigue pits, too small to see one by one, that give tooth flanks a dull gray look.
Lambda ratio
Oil film thickness divided by combined surface roughness, showing how well the lubricant separates the teeth.
Gear grinding
Finishing hardened gear teeth with abrasive wheels to correct heat treat distortion and reach high accuracy.