Rectangle shape, the casing of this serial of resistance furnace is made up of excellent steel plates and soldered in hems.The work room is made up with flame-proofing materials manufactured into bulk encasing hearth with inlaid heating elements. Between the hearth and casing are the fire resistant and thermal insulation materials.Under the furnace mouth, there is safety switch interlocking with the furnace door, which will automatically cut off the power supply when furnace door opened to ensure safety.