We do metal machining for the auto parts we make. The parts we make get randomly checked a couple of times per shift for all of the necessary specifications down to a couple hundredths of a millimeter variance.

If a part checks out of spec, the production of those parts are shut down and an engineer comes out to do what is necessary to make good parts again.

While they are doing that, quality control goes to the parts that were made by the out of spec machine and checks them, from oldest produced since the last line check, to the newest produced, until they find where the bad parts started getting made. They are then quarantined and sorted and measured, throwing out all out of spec parts.

They are all virtually identically, only having slight differences of no more than 0.02mm