tempering-machine

from The Century Dictionary.

• noun A heating-machine having reels which support trays on which needles and other small steel articles are placed to be tempered, or a furnace with a spiral conveyer or a tumbling-barrel. The aim is to expose the steel pens, scrows, buttons, saw-teeth, or other objects to the action of heat and the mechanical action of hot sand or other cleaning material in some form of agitator.