Investment
Casting Process
1. WAX INJECTION
Wax replicas of the desired castings are produced
by injection molding. These replicas are called patterns.
2. ASSEMBLY
The patterns are attached to a central wax stick,
called a sprue, to form a casting cluster or assembly.
3. 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.
4. DEWAX
Once the ceramic is dry, the wax is melted out, creating
a negative impression of the assembly within the shell.
5. CONVENTIONAL 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.
6. KNOCKOUT
When the metal has cooled and solidified, the ceramic
shell is broken off by vibration or water blasting.
7. CUT OFF
The parts are cut away from the central sprue using
a high speed friction saw.
8. FINISHED CASTINGS
After minor finishing operations, the metal castings--identical
to the original wax patterns--are ready for shipment
to the customer.
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