Plug mold assembly

Abstract

A method of forming a mold for use in casting is disclosed. The method includes as a first step forming a positive pattern having a surface the shape of a part to be cast. Next a negative partial pattern is formed having a casting surface complimentary to a selected portion of the surface of the positive pattern and also having a reference surface in a fixed spatial relationship with the casting surface. The casting surface of the negative partial pattern is placed in complimentary engagement with the selected portion of the surface of the positive pattern to form a pattern assembly. A first mold section having a surface complimentary to the reference surface and to the surface of the part is formed by dipping the assembly formed in the preceding step in a ceramic material. A second mold section of ceramic material is formed having a casting surface identical to the casting surface of the negative wax partial pattern and a reference surface identical to the negative partial pattern reference surface, the casting and reference surfaces bearing the same spatial relationship to each other as the identical surfaces of the wax partial pattern bear to each other. Finally, a core is attached to one of the mold sections and a complete mold is formed by placing the reference surface of the second mold section in abutting engagement with the complimentary surface of the first mold section.