The Lost Wax Method
The lost wax method of casting has roots that date back thousands
of years. The modern method used at PPCP involves the creation of
a wax pattern that will ultimately be replicated in cast steel.
A pattern (copy of the final part) is created in wax which is then
attached to a Styrofoam sprue or tree, as it is sometimes called.
The entire assembly is then dipped in successive layers of ceramic
slurry and stucco to create a shell mold. The slurry is composed
of zircon, fused silica, and alumina silicate flours ground to exact
specifications. The flours are combined with colloidal silica binder
and polymer (which acts as a glue) to create a "liquid ceramic."
The layers of liquid ceramic coated in sand materials create a shell
that will contain liquid steel until it has solidified.
Once the shell is completed and dried, the wax is melted out leaving
a hollow mold. This is the reason it is termed "lost wax,"
as the wax has been removed from the shell. The shell is then preheated
at 1800 degrees F and molten steel is poured into the shell. Once
the steel has solidified, the shell is removed and what remains
is steel castings that are a replica of the wax part.
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