The Basics of the
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. (Hitchiner prefers to use its superior
countergravity casting technology.)
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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Last modified and validated 1-April-1998.
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