1.1 Additive Manufacturing of Ceramics for Direct Digital Investment Casting
Turbine airfoils with extremely complex internal cooling passages are produced through investment casting. The exterior airfoil shapes are defined by injection-molded wax patterns that are removed or “lost” after shelling. The internal cooling passages are defined by injection-molded ceramic cores that are removed or “lost” after casting. The core and wax molding operations require sophisticated tooling, leading to excessive initial and maintenance costs, very slow fabrication cycles, and low casting yields. Despite the maturity of current investment casting practices in the aerospace industry, a major challenge exists in the affordable, high-yield, production of cooled, single crystal nickel-superalloy airfoils for turbine engines. While many improvements in the performance of designs have been made, no significant improvements have been made to lower the cost of manufacturing turbine airfoils.