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Manufacturing:
Metal Casting
Variation
of Green Sand Molding
Skin
Dried Molding
Skin-dried
or air-dried molds are sometimes preferred
to green sand molds where assurance is desired
that the surface moisture and other gas-forming
materials are lowered. By skin drying the
face of the mold after special bonding materials
have been added to the sand molding mixture,
a firm mold face is produced similar to
that obtained in dry sand practice. Shakeout
of the mold is almost as good as that obtained
with green sand molding. Skin-dried molds
are commonly employed in making medium-heavy
and heavy castings.
Generally, the surface of
the mold is washed or sprayed with a refractory
mold coating. The most common method of
drying the refractory mold coating uses
hot air, gas or oil flame. Skin drying of
the mold can be accomplished with the aid
of torches, a bank of radiant heating lamps
or electrical heating elements directed
at the mold surface.
Advantages
- This process reduces
surface moisture and other gas-forming
materials from mold. It can commonly be
used in the production of medium-heavy
to heavy castings.
Disadvantages
- These molds are more
expensive to produce. Mold sections must
be completely dry and cool prior to assembly.
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