Case
Case turns up in 2 fields: heat treating, mining. Here is what it means to the people in each one.
Case in heat treating
The hardened outer layer of a case-hardened part, as opposed to its softer, tougher core.
Surface zone whose chemistry or structure has been changed to make it harder than the interior, by carburizing, carbonitriding, nitriding, induction or flame hardening. The case carries wear and contact stress while the core supplies toughness. A carburized gear typically has a 58 to 62 HRC case over a core of 30 to 45 HRC, and the case depth is the controlling dimension.
"Case is right on at 60 HRC but the core's only 25, so check what steel they actually sent us."
Case in mining
A small geological fissure that leaks water into mine workings.
A narrow geological fissure or joint in the rock mass that acts as a conduit for groundwater to enter the mine workings. While small in aperture, these cracks can release highly pressurized water streams that flood headings and weaken the surrounding strata.
"We intersected a case on the hanging wall and it's pumping out fifty gallons a minute, so get the sump pumps rigged."