| 摘要 |
Precision castings, such as brake calipers and 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 (12), 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 (10) with a captured core (12), the core (12) is melted from the casting in a liquid bath, in an air or gas furnace, or during 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 (10) that is extremely smooth and meets stringent tolerance requirements and because the melt-away core (12) can be formed with protrusions that prevent mechanical removal of the core (12) from the casting and that form undercuts, threads, bores, etc. in the casting.
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