casting 2012
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Casting
2
Casting since about 4000 BC…
Ancient Greece; bronzestatue casting circa 450 BC
Iron works in early Europe,e.g. cast iron cannons fromEngland circa 1543
Two Categories of Casting Processes1. Expendable mold processes - mold is
sacrificed to remove part
2. Permanent mold processes - mold is made of metal and can be used to make many castings
Casting Methods
• Sand CastingHigh Temperature Alloy, Complex Geometry, Rough Surface Finish
• Investment CastingHigh Temperature Alloy, Complex Geometry, Moderately Smooth Surface Finish
• Die CastingHigh Temperature Alloy, Moderate Geometry, Smooth Surface
Sand Casting
Uses sand to hold the desired shape to be
cast
Bonded with chemicals or clay with water or
oil
Many different types of sand casting
Sand Casting
Sand Casting Steps
cope: top half
drag: bottom half
core: for internal cavities
pattern: positive
funnel sprue runners gate cavity {risers, vents}
Investment CastingA refractory material (investment) is poured
around or built up on a pattern
The investment is hardened by drying or
heating
The pattern is removed by melting or
burning
Metal is poured into the resulting cavity
Investment Casting
(a )Wax pattern( injection
molding)
(b )Multiple patterns assembled to wax
sprue
(c )Shell built immerse into ceramic
slurry immerse into fine
sand( few layers)
(d ) dry ceramic melt out the wax fire ceramic (burn
wax)
(e ) ) (Pour molten metal gravity cool, solidify
[ Hollow casting : pouring excess metal before
solidification
(f ) Break ceramic shell ( vibration or water
blasting)
(g )Cut off parts( high-speed friction
saw) finishing (polish)
Investment Casting Steps
Die CastingHuge numbers of small, light castings can
be produced with great accuracy.
Little surface finishing is required.
Permanent mold (dies can be used over and
over)
Die Casting
Die CastingSteps
• Reference:
Metal Casting book
http://en.wikipedia.org
Casting
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