Abstract: Vented mold having a molding cavity defined by a wall that is too thick for suitably laser-drilling small holes therethrough. The wall has a front-face confronting the molding cavity, and a back-face opposite the front-face. The backface is drilled to a depth less than the thickness of the wall to provide a well in the back-face that has a bottom which is a thin portion of the wall. The thin portion of the wall has a thickness suitable for laser-drilling, and is laser-drilled with a plurality of vent holes less than 0.36 mm. in diameter.

Abstract: Method of making a subcutaneous melt flow-channel in the surface of a fugitive foam pattern used in lost-foam casting process. After a refractory skin has been formed on the surface of a foam pattern, a strip of the skin is treated so as to cause the foam underlying the strip to recede from the strip and leave a groove in its stead. Suitable treatments include (1) heating the strip, or (2) applying a foam solvent thereto that soaks through the skin. In each case, the treatment is such as to cause the foam underlying the treated strip to soften and recede from the strip.