No. 939 is a 2000°F gas-heated box furnace from Grieve used for preheating metals prior to forging. Workspace dimensions measure 72 inches wide x 36 inches deep x 48 inches high. Two modulating 700,000-BTU natural gas burners with a floor-mounted combustion air blower heat the unit. This furnace features 7-inch insulated walls made with 5 inches of 2300°F ceramic fiber and 2 inches of 1700°F ceramic fiber. The 7-inch floor is comprised of 4.5 inches of 2300°F firebrick and 2.5 inches of 1900°F block insulation. A firebrick plate hearth is supported by firebrick piers, and the unit has a manually operated vertical lift door. No. 939 also includes a digital indicating temperature controller, manual reset excess temperature controller with separate contactors and a fused disconnect switch.
Check out the October 2020 issue of FORGE, featuring our cover story on "Fever Screening and Forging Quality". Other features include "Forging with Hybrid Steel", "FutureForge in Scotland: The Goldilocks Effect", and much more.