 Investment
Casting Process
Conventional Shell Casting
Investment casting, or the "lost wax" process
has been in use since the construction of the first pyramid. The Egyptians
and Chinese used the process in their early history to make statues and
jewelry. The investment casting method was largely ignored as an industrial
process for the fabrication of parts until the demand for rapidly finished
parts during World War II created the need for "near net-shape" components
that could readily be put into their final form. At this time new inorganic
high temperature ceramic mold binders were developed to industrialize
the process applications to include high strength and corrosion resistant
materials such as low to high carbon alloy steel, tool steel, stainless
steel, and nickel and cobalt base alloys. Aluminum and brass alloys are
available also.
It is a process capable of producing intricate shapes weighing
from a small fraction of an ounce up to forty pounds or more. Some examples
would be: dental appliances, jewelry, components for the automotive industry,
military weaponry, jet engines, aircraft structural parts, machinery
components, and many others.
In general, an injection molded wax pattern
is used for each part produced which is then encased in multiple layers
of ceramic material. The wax pattern is then removed from the ceramic
shell mold. The mold is fired in an oven and then molten metal is poured
into the cavities left by the evacuated wax pattern. Upon cooling, the
resulting precision castings are cleaned and subjected to further processing
such as heat treatment. At this point, many parts are in their final form
and are ready for use while others may require a small amount of further
processing such as machining before reaching their final form.
Because
we build our ceramic molds exclusively by hand, we specialize in producing
complex detail, which is not always possible for foundries that utilize
robots. Our cosmetics are as good as any foundry can offer, better than
most. Chicago Vacuum produces castings with an exceptionally smooth finish,
typical dimension accuracy of +/- .005” and the capabilities of holding
as close as +/-.003” when
required. Our production lead times are among the shortest in the industry,
and our quality system is based upon MIL-I-45208 with an ongoing objective
of becoming ISO-9002 compliant throughout our facility. We also have the capabilities
of furnishing secondary operations such as machining, non destructive testing,
plating, coating, heat treat, and assembly. We also subcontract the construction
of molding tools which are produced from 7075-T651 aircraft aluminum quality.
We also employ a unique Solid Mold Process.
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Process