Matrix Riser Breaker Insert

Abstract

A casting system for molding metal. The casting system has a mold comprising a cavity in a predefined shape. A riser in flow communication with the mold wherein the riser provides molten metal to said cavity as the molten metal freezes. A riser breaker insert is between the mold and the riser wherein the riser breaker insert comprises voids. A molten metal supply is provided which is capable of filling the mold and the voids of said riser breaker insert and at least partially filling the riser.

Claimed is: 
     
         1 . A casting system for molding metal comprising:
 a mold comprising a cavity in a predefined shape;   a riser in flow communication with said mold wherein said riser provides molten metal to said cavity as said molten metal freezes;   a riser breaker insert between said mold and said riser wherein said riser breaker insert comprises voids;   a molten metal supply capable of filling said mold and said voids of said riser breaker insert and at least partially filling said riser.   
     
     
         2 . The casting system for molding metal of  claim 1  wherein said riser breaker insert comprises a ceramic. 
     
     
         3 . The casting system for molding metal of  claim 2  with a ceramic density of at least 30% of theoretical density. 
     
     
         4 . The casting system for molding metal of  claim 2  wherein said ceramic is selected from the group consisting of fired clay, mullite, alumina, zirconia-toughened alumina, zirconia-toughened mullite, silicon carbide, silica-bonded mullite, and silica-bonded silicon carbide. 
     
     
         5 . The casting system for molding metal of  claim 1  wherein said riser breaker insert comprises minor voids and major voids. 
     
     
         6 . The casting system for molding metal of  claim 1  wherein said riser breaker insert comprises solid filaments. 
     
     
         7 . The casting system for molding metal of  claim 6  wherein said solid filaments represent a bulk density of said riser breaker insert. 
     
     
         8 . The casting system for molding metal of  claim 7  wherein said bulk density is at least 10 vol % to no more than 50 vol %. 
     
     
         9 . The casting system for molding metal of  claim 6  wherein said solid filaments form structural rings. 
     
     
         10 . The casting system for molding metal of  claim 6  wherein said solid filaments comprise a serpentine pattern. 
     
     
         11 . The casting system for molding metal of  claim 1  wherein said riser breaker insert has a cross-sectional shape. 
     
     
         12 . The casting system for molding metal of  claim 11  wherein said cross-sectional shape is trapezoidal. 
     
     
         13 . A molded metal formed by the system of  claim 1 . 
     
     
         14 . The molded metal of  claim 13  comprising iron. 
     
     
         15 . The molded metal of  claim 14  wherein said iron comprises ductile iron. 
     
     
         16 . A ceramic riser breaker insert comprising:
 a matrix of solid ceramic filaments forming a gross shape with an inner boundary, an outer boundary and a bulk density of at least 10 vol % to no more than 50 vol % between said inner boundary and said outer boundary.   
     
     
         17 . The ceramic riser breaker insert of  claim 16  wherein said ceramic is selected from the group consisting of fired clay, mullite, alumina, zirconia-toughened alumina, zirconia-toughened mullite, silicon carbide, silica-bonded mullite, and silica-bonded silicon carbide. 
     
     
         18 . The ceramic riser breaker insert of  claim 16  wherein said riser breaker insert comprises minor voids and major voids. 
     
     
         19 . The ceramic riser breaker insert of  claim 16  wherein said riser breaker insert comprises solid filaments. 
     
     
         20 . The ceramic riser breaker insert of  claim 19  wherein said solid filaments represent a bulk density of said riser breaker insert. 
     
     
         21 . The ceramic riser breaker insert of  claim 20  wherein said bulk density is at least 20 vol % to no more than 40 vol %. 
     
     
         22 . The ceramic riser breaker insert of  claim 19  wherein said solid filaments form structural rings. 
     
     
         23 . The ceramic riser breaker insert of  claim 19  wherein said solid filaments comprise a serpentine pattern. 
     
     
         24 . The ceramic riser breaker insert of  claim 16  wherein said riser breaker insert has a cross-sectional shape. 
     
     
         25 . The ceramic riser breaker insert of  claim 24  wherein said cross-sectional shape is trapezoidal. 
     
     
         26 . The ceramic riser breaker insert of  claim 16  wherein said solid ceramic filaments have a ceramic density of at least 30% theoretical density. 
     
     
         27 . A method for casting metal comprising:
 positioning a mold comprising a cavity;   attaching a riser in flow communication with said mold;   inserting a riser breaker insert between said mold and said riser wherein said riser breaker insert comprises voids;   charging said mold with an excess of molten metal wherein said molten metal fills said mold, at least partially fills said riser and at least partially fills said voids in said riser breaker insert;   cooling said molten metal in said mold wherein upon said cooling said molten metal contracts;   allowing molten metal to pass from said riser through said voids of said riser breaker insert to maintain a full mold as said molten metal contracts thereby forming a blank comprising a cast, waste and said riser breaker in said blank between said cast and said waste; and   separating said cast from said waste at said riser breaker insert.   
     
     
         28 . The method for casting metal of  claim 27  wherein said riser breaker insert comprises a ceramic. 
     
     
         29 . The method for casting metal of  claim 28  wherein said solid ceramic filaments have a ceramic density of at least 30% theoretical density. 
     
     
         30 . The method for casting metal of  claim 28  wherein said ceramic is selected from the group consisting of fired clay, mullite, alumina, zirconia-toughened alumina, zirconia-toughened mullite, silicon carbide, silica-bonded mullite, and silica-bonded silicon carbide. 
     
     
         31 . The method for casting metal of  claim 27  wherein said riser breaker insert comprises minor voids and major voids. 
     
     
         32 . The method for casting metal of  claim 27  wherein said riser breaker insert comprises solid filaments. 
     
     
         33 . The method for casting metal of  claim 32  wherein said solid filaments represent a bulk density of said riser breaker insert. 
     
     
         34 . The method for casting metal of  claim 33  wherein said bulk density is at least 10 vol % to no more than 50 vol %. 
     
     
         35 . The method for casting metal of  claim 32  wherein said solid filaments form structural rings. 
     
     
         36 . The method for casting metal of  claim 32  wherein said solid filaments comprise a serpentine pattern. 
     
     
         37 . The method for casting metal of  claim 27  wherein said riser breaker insert has a cross-sectional shape. 
     
     
         38 . The method for casting metal of  claim 37  wherein said cross-sectional shape is trapezoidal. 
     
     
         39 . The method for casting metal of  claim 27  wherein said separating includes impact with a kinetic breaker. 
     
     
         40 . The method for casting metal of  claim 39  wherein said impact is in a plane comprising said riser breaker insert. 
     
     
         41 . A molded metal formed by the method for casting metal of  claim 27 . 
     
     
         42 . The molded metal of  claim 41  comprising iron. 
     
     
         43 . The molded metal of  claim 42  wherein said iron comprises ductile iron. 
     
     
         44 . A method of forming a ceramic riser breaker insert comprising:
 forming a ceramic precursor;   extruding said ceramic precursor into filaments to form an inner boundary, an outer boundary, top filaments spanning between said inner boundary and said outer boundary and bottom filaments spanning between said inner boundary and said outer boundary thereby forming a green riser breaker insert;   heating said green riser breaker insert to sinter said ceramic precursor thereby forming said ceramic riser breaker insert.   
     
     
         45 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said ceramic is selected from the group consisting of fired clay, mullite, alumina, zirconia-toughened alumina, zirconia-toughened mullite, silicon carbide, silica-bonded mullite, and silica-bonded silicon carbide. 
     
     
         46 . The method of forming a ceramic riser breaker insert of  claim 44  having a ceramic density of at least 30% theoretical density. 
     
     
         47 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said riser breaker insert comprises minor voids and major voids. 
     
     
         48 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said riser breaker insert has bulk density of at least 10 vol % to no more than 50 vol %. 
     
     
         49 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said filaments form structural rings. 
     
     
         50 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said filaments comprise a serpentine pattern. 
     
     
         51 . The method of forming a ceramic riser breaker insert of  claim 44  wherein said riser breaker insert has a cross-sectional shape. 
     
     
         52 . The method of forming a ceramic riser breaker insert of  claim 51  wherein said cross-sectional shape is trapezoidal.