Abstract: Precision castings requiring a fine finish and having complex internal geometries can be produced by casting a semi-solid thixotropic metal alloy within or about a melt-away metal component in the form of a core and/or a die insert that has a lower melting point than the solid-to-semi-solid transition temperature of the thixotropic alloy The thixotropic alloy may be cast, e.g., by thixocasting, rheocasting, sub liquidus casting. Then, after the alloy solidifies to form a casting with a captured melt-away component, the component is melted from the casting, preferably using a liquid bath. Process robustness, speed, and versatility can be enhanced by coating the component with a thin, uniform, abrasion-resistant, and thermally resistant coating that prevents excessive heat from being transferred to the component from the alloy and that prevents the component from alloying with the casting.

Abstract: Precision castings requiring a fine finish and having complex internal geometries can be produced by casting a semi-solid thixotropic metal alloy within or about a melt-away metal component in the form of a core and/or a die insert that has a lower melting point than the solid-to-semi-solid transition temperature of the thixotropic alloy The thixotropic alloy may be cast, e.g., by thixocasting, rheocasting, sub liquidus casting. Then, after the alloy solidifies to form a casting with a captured melt-away component, the component is melted from the casting, preferably using a liquid bath. Process robustness, speed, and versatility can be enhanced by coating the component with a thin, uniform, abrasion-resistant, and thermally resistant coating that prevents excessive heat from being transferred to the component from the alloy and that prevents the component from alloying with the casting.

Abstract: Precision castings, such as brake calipers and other parts requiring a fine finish and having complex internal geometries, can be produced by casting a shot of a semi-solid thixotropic metal alloy about a core, preferably a hot-chamber die-cast core, having a lower melting point than the solid-to-semi-solid transition temperature of the thixotropic alloy. Then, after the shot solidifies to form a casting with a captured core, the core is melted from the casting in a liquid bath, in an air furnace, or during other heat treatment of the part. The process dramatically reduces or even eliminates machining requirements for cast metal parts because the inner surface of the casting is of extremely low porosity and meets stringent tolerance requirements and because the melt-away core can be formed with protrusions that prevent mechanical removal of the core from the casting and that form undercuts, threads, bores, etc. in the casting.

Abstract: Precision castings such as brake calipers and other cast metal parts requiring a fine finish and having complex internal geometries can be produced by casting a shot of a semi-solid thixotropic metal alloy in a die having one or more inserts that have a lower melting point than the solid-to-semi-solid transition temperature of the thixotropic alloy. A core of the same or similar material may also be placed in the die between the inserts. Then, after the shot solidifies to form a casting, the inserts and core (if present) are melted from the casting.