IF FURNACES COULD TALK….
Molten metal is delivered from a melting furnace to holding furnaces in a die cast facility. A casting is made by drawing down the molten metal from the holding furnace.
A zinc die casting client has a unique situation. Their metal draw down is large from their immersion holding furnace. This causes thermal shock to the refractory and exposure of the electric elements to air. When the metal in the furnace is drawn down, the exposed electric elements are stressed causing premature failure as well as reduced recovery time of the metal temperature. Before you know it, there is solidified metal in the bottom of the zinc pot.
Note: Electric elements are not able to be “high fired” like gas burners in order to help recover extreme temperature changes.
Solution to the Problems
Onex upgraded the refractory to a mullite based, non-wetting, high strength material to address the thermal shock created by the heavy draw down of the metal level. Also, a state of the art insulation was used in the furnace floor to prevent heat from escaping through the metal shell and help maintain the molten metal temperature. In addition, Onex is proposing a more robust, immersion style element system. The tubes will be structurally strong to survive in an industrial environment and operate under frequent thermal cycling.
Finished Product – Just Like New