Method of making a mold

Abstract

An improved method is utilized to make a mold for a cast product having a plurality of spaced apart surfaces. Although the method could be used for forming molds for different products, the method is advantageously used to form a mold for a cast product having a plurality of airfoils disposed in a circular array. To form the mold, a plurality of airfoil pattern segments are placed in a circular array with surfaces of the segments abutting at joints which are free of material interconnecting the segments. A coating of liquid ceramic mold material is applied over the airfoil pattern segments. Since the joints between the airfoil pattern segments are free of interconnecting material, the liquid ceramic mold material can flow into the joints. After the ceramic mold material has been dried and the airfoil pattern segments disposed of, the ceramic mold material which entered the joints between the airfoil pattern segments forms a plurality of relatively thin projections from the main wall of the mold. These thin projections are broken away before the product is cast in the mold. During the application of the ceramic coating to the airfoil pattern segments, the relatively flexible wax airfoil pattern segments are advantageously supported by a relatively rigid annular pattern member which is disposed outwardly of the airfoil segments.