WILLIAM G THOMAS, MD
Medical Practice at Spring St, Gainesville, GA

4972897, Nov 27, 1990

Feb 2, 1990

7/473832

William R. Thomas - Gainesville GA

MDS Products Inc. - Anaheim CA

B22C 904

164 35

Apparatus useful in forming a mold from a wax pattern in an investment casting process, the invention provides a loop element having arm elements which spiral downwardly from and inwardly of the loop element to a base element. Sprue pins mount wax patterns to the loop element in a casting process known as the "lost wax" technique, the apparatus of the invention being particularly useful in the environment of a dental laboratory for formation of crowns and the like of high density. The loop element and arm elements of the apparatus leave channels in the investment material on "burn out" which quickly accelerate a casting material, such as a metal alloy, into the formed mold or molds with a reduction of turbulence which results in fewer defective castings. The channel geometry provided by the apparatus provides benefits due to a lack of right angles or sharp corners which restrict the flow of casting material into the mold or molds.