COUNTERGRAVITY CASTING USING PARTICULATE SUPPORTED THIN WALLED INVESTMENT SHELL MOLD

摘要

An expendable pattern of an article to becast comprises a meltable material that expands uponheating (e.g., a wax pattern). The pattern isinvested with particulate mold material to form athin, layered shell having a wall thickness notexceeding about .12 inch. The thin shell wallthickness unexpectedly reduces damage and distortionto the shell during removal of the pattern therefromby steam autoclaving. After firing, the thin gaspermeable shell mold is surrounded by a refractoryparticulate support media in a vacuum housing. Thevacuum housing is then evacuated to evacuate the moldcavity defined by the thin shell and concurrently apressure is applied to the support media so as tocompress the support media about the thin shell tosupport the shell against casting stresses when moltenmetal is countergravity cast into the evacuated moldcavity.