Abstract: A permanent metal mold (12) has a casting cavity (18) within which variable thickness molten metal articles (20) are cast. Portions (26) of the casting cavity walls (16) are formed oversized and lined with sand (44) to conform with the external size and shape of certain thick (46) and thin (48) sections of the cast article (20). The thickness of the sand liner (44) is reversely correlated to the thick (46) and thin (48) sections of the article (20) to cause these sections (46, 48) to cool at different rates in order to achieve an approximately equalized cooling time of these sections (46, 48). Other portions (50, 52) of the casting cavity walls (16) are formed bare of the sand liner (44) and conform with the external size and shape of other corresponding sections (54, 56) of the cast article (20).

Abstract: A mold within which molten metal is sand cast, is provided with strategically located chill plates which shape and rapidly cool the molten metal at predetermined locations for hardening those locations relative to the hardness of the remainder of the casting. The mold is formed of a cope and drag frame type flask within which sand is compacted to form the sand cavity. Plates are arranged transversely of the casting cavity and are secured to portions of the flask frame for dissipating heat through the plates and out through the frame. The plates are fixed to portions of the flask and are arranged in opposing pairs which are aligned, coplanar, in abutting relationship. Each plate of each pair is provided with a notch, aligned with its opposite plate, for encircling the portion of the casting to be chill hardened. The pattern used for forming the cavity extends through the aligned notches and between the plates to form the composite sand and metal plate casting surface in the cavity.

Abstract: A method of casting a metal matrix composite involves countergravity filling a bottom-gated casting mold from an underlying, initially homogenous, two-phase melt of solid reinforcing particles in a molten metal while continuously inductively stirring the melt during countergravity filling of the mold to minimize subsequent clumping or agglomeration of the reinforcing particles therein during mold filling. After the casting mold is filled, the melt in the mold may be inductively stirred during solidification therein to minimize subsequent clumping or agglomeration of the reinforcing particles in the solidifying melt. A cast metal matrix composite having the reinforcing particles uniformly dispersed in a metal matrix and substantially free of objectionable clusters of the reinforcing particles in the metal matrix is thereby provided.

Abstract: Apparatus for the vacuum-assisted, countergravity casting of thin-walled metal parts includes a plurality of expendable casting molds supported on a top side of a reusable drag slab. Each casting mold includes a mold cavity and a mold ingate passage extending from the mold cavity into registry with a respective underlying slab ingate passage that extends between the top side and a bottom side of the drag slab and that optionally includes a molten metal filter therein. When the bottom side of the drag slab is immersed in an underlying molten metal pool with the mold cavities evacuated, the molten metal is drawn upwardly through each slab ingate passage and the molten metal filter therein and then through each mold ingate passage registered therewith into each mold cavity. The molten metal filter in each slab ingate passage removes inclusion-forming impurities from the molten metal as it is drawn upwardly into each mold cavity.

Abstract: Apparatus for the countergravity, shell-mold casting process comprising a gas-permeable shell mold sealed in the mouth of a vacuum chamber and a hollow, expendable, gas-permeable, thermally degradable, core disposed with the molding cavity for engulfment and retention by the metal being cast. The core defines a central evacuation cavity and an unobstructed vent for exhausting the evacuation cavity into the vacuum chamber such that the pressure in the evacuation cavity is substantially equal to that in the vacuum chamber during casting.