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1. Green Sand Process |
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In sand casting, the mold
is formed around a pattern by ramming sand, mixed with the proper bonding agent,
onto the pattern. Then the pattern is removed, leaving a cavity in the shape of
the casting to be made. Molten metal is poured into the mold, and after it has solidified
the mold is broken to remove the casting. In making molds and cores, various agents
can be used for bonding the sand. The agent most often used is a mixture of clay
and water.
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2. Dry Sand Process |
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large components are very difficult to cast to
exact size and dimensions. Hence, some foundries use dry sand molds to produce such
parts. Dry sand molding is the green sand process modified by baking the mold at
prescribed temperature. Engine blocks, large gears, big housings, construction parts,
are examples of dry sand process candidates. Ferrous and non-ferrous metals are
cast in this method.
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3. Co2 Process |
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A process for hardening molds or cores in which
carbon dioxide gas is blown through dry clay-free silica sand to precipitate silica
in the form of a gel from the sodium silicate binder. See Silica Sand. |
4. Shell Process |
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Process in which clay-free silica sand coated
with a thermosetting resin or mixed with resin is placed on a heated metal pattern
for a short period of time to form a partially hardened shell. The bulk of the sand
mixture inside the resulting shell is removed for further use. The pattern and shell
are then heated further to harden or polymerize the resin-sand mix, and the shell
is removed from the pattern.
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5. Cold Box Process |
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A rapid coremaking process which does not require
application of heat to cure the cores. Hardening of the cores is accomplished by
chemical reaction rather than by conventional baking. A phenolic resin is added
to the sand used to make the core. This resin reacts chemically when exposed to
an accelerator, typically an active organic gas, and hardens very quickly, forming
an organic bond in the core sand.
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6. Molasses Process |
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A solution of water and molasses sprayed on sand
molds to strengthen mold surface and yield a fine finish layer. |
7. No Bake Process |
Molds/cores produced with a resin bonded air
setting sand. Also known as the air set process because molds are left to harden
under normal atmospheric conditions.
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