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Manufacturing:
Metal Casting
Variation
of Green Sand Molding
Dry
Sand Molding
Dry sand molding is the
green sand practice modified by baking the
mold at 400-600F (204-316C). Some foundries
use dry sand molds to produce intricate
parts which are difficult to cast to exact
size and dimensions. Molds are generally
dried (or baked) in large mold drying or
with large mold heaters.
Castings of large or medium
size and of complex configuration such as
frames, engine cylinders, rolls, large gears
and housings are often made using the dry
sand technique. Both ferrous and nonferrous
metals are cast in this type of mold.
Advantages
- Dry sand molds are generally
stronger than green sand molds and therefore
can withstand much additional handling.
- Better dimension control
than if they were molded in green sand.
- The improved quality
of the sand mixture due to the removal
of moisture can result in a much smoother
finish on the castings than if made in
green sand molds. Where molds are properly
washed and sprayed with refractory coatings,
the casting finish is further improved.
Disadvantages
- This type of molding
is much more expensive than green sand
molding and is not a high-production process.
Correct baking (drying) times are essential.
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