Press Fit
A type of joint held purely by mechanical interference, formed by slowly forcing two extremely tightly-fitting parts together with a press
Ball Bearing
A mechanical device for allowing two pieces to slide independently, separated by extremely round and hard metal balls
Hardness Tester or Hardness Checker
Device for characterizing the hardness of a metal part, typically by pushing on it until it gives slightly.
Turning between centers
An operation performed between two centers (hardened pointed holding devices) on a rotary machine tool called a lathe.
Nut
Any internally threaded shell used to turn rotary into linear motion or force.
Lock Nut
A nut specialized to grab the threads, frequently using deformable plastic, which such force that it cannot easily be un-fastened (e.g. to resist vibration)
Bonus from the steel mill:
Tuyere
A specialized refractory nozzle installed in the bottom of steelmaking vessels (blast furnaces, some metallurgical furnaces, etc.) to allow high-pressure gas to be forced into the hot metal bath to drive chemical reactions. Somehow not an obscure slur; pronounced tweer.
