The depth of the hardened layer produced by carburizing, nitriding or induction hardening. Effective case depth is commonly measured from the surface to the point where hardness falls to 50 HRC, on a sectioned test coupon or sample. It is scaled to tooth size: too shallow and subsurface stresses crack the case or cause tooth interior fatigue, too deep and tips turn brittle and cycle time grows.
Effective case depth came in at 0.8 millimeters on a 6 module gear, that's light, quality wants a new coupon from the next load.
Also heard as
- effective case depth
- ECD
- case
Related terms
Carburizing
A heat treatment that diffuses carbon into the surface of low-carbon steel gears, then quenches for a hard case.
TIFF
Tooth interior fatigue fracture: a crack that starts deep inside a case-hardened tooth, not at its surface.
Spalling
Large, irregular flakes broken out of a tooth surface, usually where pits have grown and joined.
Induction hardening
Hardening gear teeth by heating them locally with an induction coil and quenching immediately.