The parts to be treated are introduced into the furnace and are moved forward by means of mechanical or hydraulic pushers.
The parts subject to this thrust must have a smooth surface and the resting plane (hearth) must be able to bear the pushing efforts, push the parts forward and slide along guides.
Since the surfaces must have a very low coefficient of friction they are usually made in special ceramic material.

If the parts to be treated cannot be pushed (e.g. small items) they are placed on trays capable of bearing the strain.
The parts are loaded and unloaded by a computerized system.