Importance

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Abstract

The present invention provides an improved method of forming a metal article having a plurality of airfoils which extend outwardly from a hub. The metal airfoils are formed separately from the hub. In forming a mold to cast the article, blade portions of the metal airfoils are coated with wax. The metal airfoils are then placed in a circular array and are covered with a coating of liquid ceramic mold material. This wet coating of ceramic mold material is dried to form an annular mold wall section having a plurality of recesses in which the blades of the metal airfoils are disposed. The wax coating over the metal airfoil blades is subsequently removed from the recesses to provide space between the blades and the side walls of the recesses. The annular mold wall section in which the blade containing recesses are formed is then connected with top and bottom mold sections to further define a mold cavity having a configuration corresponding to the hub portion of the article. Before casting, the mold is preheated to a relatively high temperature with the blade portions of the airfoils in their associated recesses. As the mold is preheated, the metal airfoils expand to completely fill the recesses in which the blade portions of the airfoils are disposed. Molten metal is then poured into the mold cavity and cooled to form a hub which interconnects the roots of the airfoils.

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First Claim