Case depth
Case depth turns up in 2 fields: heat treating, gears. Here is what it means to the people in each one.
Case depth in heat treating
Thickness of a hardened surface layer, measured from the surface to a specified hardness or structure.
Depth of a case, measured on a sectioned sample by microhardness traverse, by etched appearance or by chemical analysis. Drawings call out either effective case depth, to a set hardness, or total case depth, to where hardness or carbon matches the core. Typical carburized gear cases are 0.5 to 1.5 mm, nitrided cases 0.1 to 0.6 mm and induction cases 1 to 6 mm.
"Customer wants case depth checked at the pitch line, not the tip, so section it through the tooth."
Case depth in gears
How deep the hardened surface layer of a gear tooth goes, usually measured to a set hardness such as 50 HRC.
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."