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Publication numberUS2822592 A
Publication typeGrant
Publication dateFeb 11, 1958
Filing dateFeb 24, 1954
Priority dateFeb 24, 1954
Publication numberUS 2822592 A, US 2822592A, US-A-2822592, US2822592 A, US2822592A
InventorsWendt Douglas C
Original AssigneeWendt Douglas C
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for making investment molds and castings
US 2822592 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Feb. 11, 1958 D, c. WENDT4 2,822,592


Application February 24, 1954, Serial No. 412,269

1 Claim. (Cl. 22-200) This invention relates generally to the art of making castings and particularly to dental castings and includes a method for making investment molds and castings.

The main object of this invention is to devise a method of and apparatus for making accurate castings of maximum density and free from voids or irregularities not present in the original pattern.

The second object is to devise an apparatus which will fit into the ordinary run of dental equipment and one which can utilize air pressures usually available in dental laboratories.

I accomplish these and other objects in the manner set forth in the following specification as illustrated in the accompanying drawing, in which Fig. 1 is a vertical section through the device.

Fig. 2 is a horizontal section taken along the line 2-2 in Fig. 1.

Fig. 3 is a perspective in section of the mold after wax has been removed by heat.

Fig. 4 is a perspective view of the removable bottom of the mold.

Referring in detail to the drawing, there is shown a base having a threaded top 11 upon which may be mounted a pressure casing 12. The casing 12 is provided with an inlet air valve 13 to which air is supplied through the hose 14 from the laboratory compressor. Either the base 10 or the casing 12 may be stationary and the other element movable. The casing 12 is also provided with a pressure gauge 15 and an exhaust valve 16. Movably placed on the base 10 is a sprue base 17. The sprue base 17 has formed therein a groove in which is seated the investment ring 18.

The wax pattern 19 is normally placed on a sprue 20 made of metal, wax, or plastic and the sprue 20 placed in the sprue base 17. The ring 18, which is lined with asbestos 21, is now placed on the base 17 and freshly mixed casting investment 22 is poured into the ring 18 to completely envelop the pattern 19. The investment 22 is allowed to set and then placed in an oven after the sprue 2 F., depending upon the technique, and allowed to remain there until all the wax is removed and a clean, red hot sprue hole is observed. From here on the casting procedure is as is now customary.

In order to overcome voids and irregularities in the casting, as well as mold distortion, I place the investment ring 18, mounted on the sprue base, and with the pattern 19 in place and the ring filled with soft investment, within the chamber 23 formed by the base 10, and a pressure of forty-five pounds gradually applied to the chamber 23. This pressure is maintained until a trial piece of the soft investment is set. The exhaust valve 16 is opened, the chamber 23 opened, and the ring 18 is ready for the firing.

The resulting casting will be found to be an exact duplicate of the original pattern without voids or distortion of any kind. Due to the pressure employed any air pockets entrapped within the material will be compressed to a point where they disappear or are made so small as to be unobjectionable.

I claim:

In the known method of making dental castings wherein a wax pattern is surrounded with a soft investment material, the investment material thereafter permitted to harden, the wax pattern drained from the interior of the hardened investment material by heating and the cavity left by the wax pattern filled with a molten metal to therebyform a metal dental casting, the improvements which comprise: a. while the investment material surrounding the wax pattern is still in a soft condition, gradually applying an air pressure of approximately 45 pounds per square inch gage directly upon all exposed surfaces of said soft investment material, b. maintaining said air pressure of approximately 45 pounds per square inch gage on said soft investment material while the hardening of the investment material is taking place, c. preventing the circulation of air completely through said investment material while it is in the process of hardening, and a. decreasing the pressure from approximately 45 pounds per square inch gage to atmospheric pressure after said in vestment material has hardened.

References Cited in the file of this patent UNITED STATES PATENTS 593,267 Adams Nov. 9, 1897 1,070,500 Mackenzie Aug. 19, 1913 1,535,017 Cline Apr. 21, 1925 1,834,101 LeMay Dec. 1, 1931 2,017,337 Berryman Oct. 15, 1935 2,507,867 Pomes May 16, 1950 2,606,347 Hildreth Aug. 12, 1952 2,632,215 Lee Mar. 24, 1953 2,652,609 Sudia Sept. 22, 1953 2,715,758 Taccone Aug. 23, 1955

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US593267 *Nov 9, 1897 Apparatus for forming sand molds
US1070500 *May 4, 1911Aug 19, 1913David Stuart MackenzieDental casting apparatus.
US1535017 *Dec 14, 1923Apr 21, 1925Jean ClineMethod for investing destructible patterns for inlay fillings
US1834101 *Mar 22, 1930Dec 1, 1931Aurora Metal Company IncCasting apparatus
US2017337 *Jul 2, 1932Oct 15, 1935Berryman Elmer HCasting furnace
US2507867 *Sep 2, 1947May 16, 1950Pomes Carlos EApparatus for investing under vacuum dental wax patterns or any other type of pattern
US2606347 *Nov 25, 1949Aug 12, 1952Ernest L HildrethInvesting machine
US2632215 *Sep 26, 1949Mar 24, 1953 Package means for sand molds
US2652609 *Jan 17, 1950Sep 22, 1953Westinghouse Electric CorpMethod of making molds
US2715758 *Apr 3, 1952Aug 23, 1955Taccone Pneumatic Foundry EquiMachine for packing sand in a mold box
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3165799 *Oct 17, 1961Jan 19, 1965Prec Metalsmiths IncProcess and slurry formulation for making precision casting shells
US3404723 *Feb 25, 1966Oct 8, 1968Bernard F. McnickleMethod for producing dental molds or molding material
US3610317 *Apr 11, 1969Oct 5, 1971James W BenfieldCrucible former
US4834091 *Apr 10, 1987May 30, 1989Ott Douglas EIntrauterine fallopian tube ostial plug and surgical process
EP0004844A2 *Dec 4, 1978Oct 31, 1979Yamato KogureApparatus for manufacturing plastic products
EP0004844A3 *Dec 4, 1978Nov 14, 1979Yamato KogureMethod and apparatus for manufacturing plastic products
U.S. Classification164/35
International ClassificationA61C13/20
Cooperative ClassificationA61C13/20
European ClassificationA61C13/20