Method of making a mold for metal casting
AssigneeGeneral Motors Corporation
InventorsMei Cai, June-Sang Siak, Richard Michael Schreck, Nicholas Edward Sargent
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Abstract
A mold for a prototype metal casting or the like may advantageously be made by forming a casting pattern of adhesively bonded aggregate particles using a binder containing a principle constituent that is soluble in supercritical carbon dioxide; forming a rigid shell mold about the pattern of materials that are unaffected by supercritical carbon dioxide; thereafter exposing the pattern and mold combination to supercritical carbon dioxide to remove the pattern binder adhesive and leave unbonded aggregate particles in the mold and removing the aggregate particles from the mold to leave a mold cavity that faithfully defines the pattern shape.
Claims7
A method of making a mold for casting a metal article comprising
- coating aggregate particles with a meltable binder film of a composition that is extractable in supercritical carbon dioxide fluid,
- shaping a volume of said particles into a casting pattern representing said article by temporarily melting said binder film on adjacent particles to adhesively join said particles in the shape of said pattern,
- forming a rigid mold around said pattern, said mold being formed of materials that are not soluble in supercritical carbon dioxide fluid,
- contacting said mold and pattern with carbon dioxide maintained at a supercritical temperature and pressure to selectively extract the binder film from the aggregate particles constituting said pattern and
- removing the unbonded aggregate particles from said mold to leave a casting cavity therein faithfully duplicating said pattern.
Dependencies are inferred from the claim text.