Introduction
Double pour or linked pour is the pouring of molten metal from two or more furnaces in a single casting. This process is used to join two or more molten metals of different temperatures and chemical compositions, to homogenize and stabilize their uniform temperature distribution necessary for the production of a high quality casting. The quality control processes for a linked pour are critical, and should be carefully monitored throughout the procedure.
Background
The double pour process is generally used in castings that merge two different metallic materials. It is often employed in high-alloy materials such as high carbon and stainless steels, that are difficult to either melt or alloy together. Complex parts that require homogenized, uniform microstructures and uniform temperatures can also benefit from a double pour process. The process is used in industries such as aerospace, automotive, and construction where steel, aluminum, and other compounds are melted and cast together.
Equipment
The equipment used in a linked pour operation is dependent on the application and complexity of the part. Generally, two large furnaces with a double-ended holding ladle are used, with a connection or port in the ladle to join the two streams. In some cases, a third smaller furnace or pour ladle may be used as well.
Before beginning the linked pour, each furnace must be brought to the correct temperature for melting the specific metal. Once ready, each furnace is filled with the desired alloy, and the metal is melted. After sufficient homogenization, the molten metal is transferred from the furnace to the holding ladle, which acts as a buffer between the furnaces. Using the port in the ladle, the molten metal from the first furnace is then transferred to the second furnace, as well as to the holding ladle. This ensures a uniform temperature distribution and homogenization of the alloys.
Process
The linked pour process typically follows these steps.
1. Preheat the ladle and furnaces.
2. Fill each furnace with the desired metal alloy.
3. Heat each furnace until the metal is melted and homogenous.
4. Transfer the molten metal from the first furnace to the holding ladle.
5. Connect the ladle or furnaces together with the port.
6. Allow the metal from the first furnace to fill both the holding ladle, and the second furnace.
7. Once both furnaces are filled, open the port to allow for simultaneous pouring.
8. Monitor the level of molten metal in the furnaces throughout the procedure.
9. Maintain a consistent pouring speed to achieve homogenization and uniform temperatures.
10. After casting, allow the metal to slowly cool.
Safety
The linked pour process can be dangerous due to the high temperatures and exposure to molten metal. For safety reasons, it is recommended that all personnel in the vicinity of the process wear the appropriate safety equipment, and follow proper safety protocols.
Conclusion
Double pour or linked pour is the process of pouring molten metal from two or more furnaces in a single casting. This process is used to join two or more molten metals of different temperatures and chemical compositions, to homogenize and stabilize their uniform temperature distribution for the production of a high quality casting. The linked pour requires specialized equipment and must be carefully monitored throughout the procedure. Safety is also of utmost importance, as the exposure to high temperatures and molten metal can be dangerous.
