Lucifer Furnaces supplied several convection ovens to a manufacturer of small medical parts in the southern United States. The units, which heat to 1200°F, are insulated with 4.5" of multilayered firebrick and 2" insulating cold face block with overlapped seams for reduced thermal loss. Temperature uniformity is achieved with recirculating airflow.
Onboard controls include a Honeywell UDC3500 digital time proportioning temperature controller with four 20-segment setpoint programs. A high limit controller from Honeywell is used to prevent temperature excursions.
The side-wall heating element banks consist of coil-wound resistance wire in ceramic holders to ease replacement. A horizontal-swing door with adjustable latch provides a firm brick-to-brick seal, according to Lucifer. A safety switch powers off both fan and heating elements when the door is opened to protect the user.