Expendable core for casting processes

Abstract

A method is provided for forming a sand core which is suitable for use in casting processes, and in particular squeeze casting processes, to form internal features and intricate external features of a cast article. The core forming method involves the use of a single-component gelatin binder whose degradation at elevated temperatures is catalyzed by additions of a ferric compound. The gelating binder is a mixture of proteins derived from amino acids such as glycine, alanine, L-glutamic acid, L-aspartic acid, and/or small percentages of others, such that the gelatin binder is water soluble and therefore easily eliminated from the core sand at the end of the casting process. Due in particular to the presence of the ferric compound, the gelatin binder readily degrades at low temperatures, such as those associated with aluminum casting processes, such that the core degrades sufficiently to permit the sand to freely flow from the cast article without the need for core removal operations. Finally, the gelatin-based binder is nontoxic, such that its elimination from the sand to reclaim the sand for reuse does not pose an environmental hazard.