Gravity casting is among the oldest known processes for fabricating metals and metal alloys. It involves the pouring of molten metal from a
crucible
A crucible is a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures. While crucibles were historically usually made from clay, they can be made from any material that withstands te ...
into a mold under only the force of gravity, without the use of pressurized gases, vacuums, or
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parall ...
. Small-scale molds used for this form of casting have most commonly been made of sand,
tufa
Tufa is a variety of limestone formed when carbonate minerals precipitate out of water in unheated rivers or lakes. Geothermally heated hot springs sometimes produce similar (but less porous) carbonate deposits, which are known as travertin ...
stone, and
cuttlebone
Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all members of the family Sepiidae, commonly known as cuttlefish, within the cephalopods. In other cephalopod families it is calle ...
as well as charcoal and plaster
as these materials are generally easy to shape (unlike iron or steel), do not break down when suddenly exposed to high temperatures (unlike glass, wood, or plastic), do not deform easily (unlike silicone) and are widely available.
References
Casting (manufacturing)
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