| What is
an "investment casting"?
Investment
casting is a process in which a wax cluster is
covered in a ceramic slurry. Once hardened the wax
is melted out of the ceramic shell. The shell is
then headed to 1800°F and molten metal is poured
in. After cooling the ceramic shell is then
vibrated and blasted off the metal products. Then
the products are cut, cleaned, and prepared for
shipping.
What
alloys can be poured as an investment casting?
As a
general rule all ferrous and non-ferrous materials
can be investment cast. Carbon, tool and alloy
steel along with the 300,400, 15-5PH and 1 7-4PH
stainless steels are most commonly poured.
What
size range of parts can investment casting
produce?
Investment
castings can range in size from a fraction of an
ounce to over 1000 pounds. Most investment casting
foundries cast parts up to 20 pounds. RLM casts
parts up to 280 pounds.
What are
the dimensional tolerances expected from an "as
cast" part?
Typically,
a linear tolerance of +/- .005 in/in is standard
for investment casting.
What
kind of quality can I expect in the surface
finish?
Because the
ceramic shell is built around a smooth wax
pattern, the finish achieved by investment casting
is excellent. A 125 micro-finish is standard and
even finer finishes can be achieved.
Isn't
investment casting expensive?
It is true
that investment castings are usually more
expensive than forged parts or those produced by
other casting methods. Investment casting,
however, makes up for this added cost by reducing
the amount of machining.
What
about the integrity of investment casting?
Investment
castings are used widely in applications that
require parts to be x-rayed and meet definite
soundness criteria. The integrity of an investment
casting can be far superior to parts produced by
other methods.
What are
the lead times I can expect when ordering
investment casting?
Typically,
6 weeks for commercial grade and 8 weeks for
ordnance. Deliveries can be negotiated and changed
for customers with special requirements. |