Patent attributes
A method is provided for removing a fugitive pattern, such as wax or other meltable pattern material, residing inside of a refractory mold by discharging condensable vapor such as steam inside the mold to contact and melt the pattern while an exterior of the mold is subjected to a non-condensing gas atmosphere such as air outside of the mold wherein the condensable vapor inside the mold and the atmosphere outside of the mold are at substantially the same pressure. Condensable vapor is condensed inside the mold where the vapor has contacted the pattern while the exterior of the mold remains free of condenate. The condensed vapor and melted pattern material are drained out of the mold. The condensed vapor can be discharged initially inside a hollow sprue of a fugitive pattern assembly to melt the sprue and then inside the mold to melt the patterns of the pattern assembly. The method allows the removal of fugitive pattern materials from molds of any thickness and reduces the cracking of the mold during pattern removal.
