Abstract: An improved mold for casting single crystal metallic articles is disclosed and comprises a ceramic investment mold having a main article cavity and having embedded at its lower end below the article cavity and in communication therewith a preformed ceramic single crystal starter insert. The preformed starter insert generates a plurality of single metallic crystals in a growth cavity and then selects one crystal for further propagation through the article cavity. A method for making such a mold is also disclosed.

Abstract: The present invention describes a preformed, multi-part casting mold having a preformed gating system integral therewith for providing smooth, bottom feeding of molten metal to the mold cavity while simultaneously removing contaminants from the metal prior to entry into the cavity. The improved mold is especially useful in casting columnar grained or single crystal metal and alloy articles, such as gas turbine blades.

Abstract: In the manufacture of hollow cast articles such as turbine blades or vanes, the article is cast in opposed halves on opposite sides of a "strong back" or mid-section, to which wax patterns are attached for the preparation of a shell mold around the strong back and patterns. The article halves, after removal from the mold, are bonded together.

Abstract: In making columnar grained castings the shell mold is spaced from the chill plate by a ceramic ring on which the mold is positioned, the ring being made thicker and/or of a different ceramic from the mold to withstand the thermal stress developing while the mold is being heated for pouring, so that the mold, not being subjected to such stresses at the base, may be made thinner for producing better castings. In this way the best mold material for the purpose may be selected, as, for example, a material to have no reaction with the alloy and, by lowering the thermal gradient decrease the likelihood of mold failure.

Abstract: In the manufacture of hollow turbine blades or vanes especially those having a columnar crystalline growth in the alloy, the blade is cast in two opposed halves against a central mold element, the latter being rigid enough to avoid deformation during heating of the mold prior to pouring and during solidification. This central element has on opposite surfaces the configurations of the inner surfaces of the hollow blade. Cooperating with this inner element are outer elements having cooperating inner surface configurations of the convex and concave sides of the blade respectively. After the blade halves are cast simultaneously in the assembled mold and removed therefrom they are bonded together to form a complete blade.