STEP 5: FURNACE – The ceramic shell molds must be fired to a range of 1600°F to 2000°F to burn out the last traces of pattern material, strengthen the shell mold, and preheat the mold to receive molten metal. This critical step ensures consistency in finish and accuracy in filling the most complex molds.
Kovatch Castings‘ two-row self-recuperative/pulse burner type pusher furnace made by Air and Energy, Inc. is designed to minimize natural gas consumption while insuring that the shell molds are the exact temperature required for pouring metal into specific molds.
The 3-zone furnace maintains incremental temperature to heat the shells to a pre-programmed optimal temperature for pouring with pinpoint accuracy.
Because the furnace is a self-recuperative, the incoming combustion air is heated to very high levels, improving furnace operating efficiency and minimizing natural gas consumption. The computer-controlled pulse burners fire independently of each other, in either shorter, or longer, controlled bursts. This function creates precise temperature control, making it possible to heat shells and hold a consistant temperature.
By controlling the shell temperature, we are also able to promote uniform, consistent cooling of the poured metal in the shell forms as required on a part-by-part basis.
Each shell mold temperature is verified throughout the entire heating process through the furnace. An infrared pyrometer measures the actual temperature of the mold just prior to exit, assuring a repeatable process.