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LOST FOAM CASTING
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Lost foam casting (LFC) is a type of
investment casting process that uses foam patterns as a mold. The method takes advantage of the properties of foam to simply and inexpensively create castings that would be difficult to achieve using other casting techniques.
Weldments and complex casting assemblies can be
made using this near net shape casting process. Similar to lost wax
investment
casting, the process uses a single ceramic coat for process step reduction. This
is a value added casting method, which reduces finish machining and increases
foundry yield for overall project cost advantages. Lost foam casting allows for the casting of parts that would otherwise be difficult to achieve in metal casting.
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Tempo's dry molding process uses self contained molds sized
for part geometry only which are run in small molding machines.
This is in contrast with
conventional steamchest methods, where the molding machine
steam-chest determines the size and functions of your mold.
Without these mold constraints,
Tempo offers open-architecture mold design for complex part
geometries to be produced easily.
This means that single and double mold cavities can often
meet your production requirements with low overall mold investment.
Our molds are heated and cooled
using Tempo’s unique mold circulation system derived from our
molded cup technology. This
process yields a smooth, glossy surface finish, and semi-flexible
molded parts. It also
allows molding of thin wall sections in your part geometry, we are
currently in production on several jobs with wall sections under
2.5mm (.100”) thickness.
Self contained molds allow the use
of Tempo’s unique collapsible cores for molded undercuts on
one-piece patterns.
We have excellent mold makers using
modern and traditional mold making techniques which we draw upon to
meet rush mold delivery schedules for new and reworked molds.
We have numerous small molding machines
which means we can deliver rapid turnaround on rush production
orders.
A History of Lost Foam Casting
The lost foam casting process originated in 1958 when H.F. Shroyer was granted a patent for this cavityless 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 (lost wax process), a pattern must be produced for every casting made.
First a foam pattern and gating system are made using a 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, heat treat, straightening and blast) are straight forward and quite similar to other casting processes.
Metal Casting
The process and / or apparatus for shaping of fluid metallic material.
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