Method and system for drying casting molds
First Claim
1. A method for drying casting molds comprising:
- providing a wet casting mold comprised of a meltable pattern having a ceramic liquid slurry coating thereon;
encapsulating the casting mold in a desiccant material;
applying a first constant vacuum level to the desiccant and casting mold;
holding the first vacuum level for a first period of hold time;
applying a second constant vacuum level to the desiccant and casting mold higher than the first vacuum level, the second vacuum level being different than the first vacuum level; and
holding the second constant vacuum level for a second period of hold time longer than the first period of hold time to produce a hardened shell.
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Accused Products
Abstract
A system and method of drying casting molds for forming metal parts is provided. In one embodiment, the method includes providing a casting mold comprised of a meltable pattern coated with a ceramic slurry containing a liquid solvent and a binder, placing the casting mold in a chamber, encapsulating the casting mold in a desiccant material, sealing the chamber sufficient to pull a vacuum in the chamber, and applying a variable vacuum to the chamber to dry the mold. In one embodiment, the vacuum is controlled and gradually increased over time from atmospheric pressure to a predetermined maximum vacuum pressure. The vacuum is preferably applied at a rate such that the meltable pattern has a temperature that does not decrease more than about 5 degrees F. from atmospheric pressure to maximum vacuum pressure in one embodiment. In another embodiment, the retained moisture level of the desiccant may be controlled to minimize temperature swings of the meltable pattern during the vacuum application.
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Citations
22 Claims
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1. A method for drying casting molds comprising:
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providing a wet casting mold comprised of a meltable pattern having a ceramic liquid slurry coating thereon; encapsulating the casting mold in a desiccant material; applying a first constant vacuum level to the desiccant and casting mold; holding the first vacuum level for a first period of hold time; applying a second constant vacuum level to the desiccant and casting mold higher than the first vacuum level, the second vacuum level being different than the first vacuum level; and holding the second constant vacuum level for a second period of hold time longer than the first period of hold time to produce a hardened shell. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for drying casting molds comprising:
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providing a casting mold comprised of a meltable pattern coated with a ceramic slurry containing a liquid solvent and a binder; placing the casting mold in a chamber; encapsulating the casting mold in a desiccant material; sealing the chamber sufficient to pull a vacuum in the chamber; applying a variable vacuum to the chamber, the vacuum being controlled so that the vacuum gradually increases from atmospheric pressure to a maximum vacuum pressure such that the meltable pattern has a temperature that does not decrease more than 5 degrees F. from atmospheric pressure to maximum vacuum pressure. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method for forming and drying an investment casting mold comprising:
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providing a wax pattern of a metal part to be cast; applying a ceramic slurry coating to the pattern containing a liquid solvent to define a wet casting mold; encapsulating the casting mold with a desiccant material; applying a vacuum to the casting mold for a total vacuum time measured from atmospheric pressure to a maximum vacuum pressure, wherein the vacuum is applied at a rate such that approximately 24% of the total vacuum time is used to increase the vacuum by approximately 75% and such that the wax pattern has a temperature that does not decrease more than 5 degrees F. from atmospheric pressure to maximum vacuum pressure. - View Dependent Claims (16, 17)
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18. A method for forming and drying an investment casting mold comprising:
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providing a meltable wax pattern of a metal part to be cast; applying a ceramic slurry coating to the pattern containing a liquid solvent to form a wet casting mold; fluidizing a bed of unheated desiccant at ambient room temperature; immersing the casting mold in the bed of desiccant; drying the casting mold by applying a controlled variable vacuum to the casting mold over a period of time, the vacuum being controlled to gradually increase from atmospheric pressure to a maximum vacuum pressure such that the wax pattern maintains a temperature that does not decrease more than 5 degrees F. from the temperature of the pattern at atmospheric pressure. - View Dependent Claims (19, 20, 21, 22)
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Specification