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The investment casting process is a complex, multi-step process. The basic steps illustrated below have been highly optimized and automated at Hitchiner Manufacturing Co., Inc.
Wax injection
Wax replicas of the desired castings are produced by injection molding. these replicas are called patterns.
Assembly
The patterns are attached to a central wax stick, called a sprue, to form a casting cluster or assembly.
Shell building
The shell is built by immersing the assembly in a liquid ceramic slurry and then into a bed of extremely fine sand. up to eight layers may be applied in this manner.
Dewax
Once the ceramic is dry, the wax is melted out, creating a negative impression of the assembly within the shell.
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Conventional (gravity) casting*
In the conventional process, the shell is filled with molten metal by gravity pouring. as the metal cools, the parts and gates, sprue and pouring cup become one solid casting.
Knockout
When the metal has cooled and solidified, the ceramic shell is broken off by vibration or water blasting.
Cut-off
The parts are cut away from the central sprue using a high speed friction saw.
Finished castings
After minor finishing operations, the metal castings—identical to the original wax patterns—are complete.
* Hitchiner normally uses its exclusive countergravity processes to produce castings.
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