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Quick Facts
The
Lost Foam Casting process is a cavity-less casting method,
using a polystyrene foam pattern imbedded in traditional green sand. The
polystyrene foam pattern left in the sand is decomposed by the molten metal.
The molten metal replaces the foam pattern, precisely duplicating all of the
features of the pattern. Like investment casting, a pattern must be
produced for every casting made.
The Process
First a foam pattern and
gating system are made using an injection molding press. Secondly, the
foam pattern and gating system are assembled into a
cluster. Then the cluster is coated with a
 permeable
refractory coating. The next step is to invest the dry coated cluster in
loose unbonded sand that is vibrated in and around the foam cluster. The
final step in the casting process is to pour the molten metal directly into the
foam cluster, decomposing the foam in the system and replacing it with metal.
The balance of the casting cleaning operations (cut-off, grind, shot blast, etc.)
are similar to other casting processes.
Lost Foam Casting Advantages
The lost foam casting process produces near net shaped parts
that often require little or no machining. Complex coring is
representative of many lost foam parts, however there are occasions where
simpler parts, with closed tolerance requirements, make good candidates.
The lost foam casting process allows design engineers to combine many parts into
one cast part. While lost foam castings are generally more expensive than
castings made by other processes, they make up for the higher cost through
reduction in the finished part cost.
Lost Foam Casting Disadvantages
Perhaps the greatest disadvantage of the lost foam process is the cost of the
tooling, which may prevent parts produced in lower volumes to take advantage of
the unique process capabilities.
Alloys
Nearly all ferrous and non-ferrous alloys may be cast using the
lost foam casting process.
Tooling
Sand mold tooling is generally made using wood, plastic or
aluminum materials.
Design and Technical
Information
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