Investment casting, in which molten metal is poured into hot molds, allows for the production of aluminum parts with extremely thin sections, knife edges and sharp detail. This article describes the various steps in the investment casting process, including patternmaking and dimensioning, the design and manufacture of shell molds, melting and casting methods, and postcasting operations such as knockout, core removal, and cleaning. It also addresses a wide range of design considerations, discusses casting defects, and provides several design examples.

Depending on the size and application, castings manufactured with the expendable mold process and with expendable patterns increase the tolerance from 1.5 to 3.5 times that of the permanent pattern methods. This article reviews the two major expendable pattern methods, such as lost foam and investment casting. It discusses the Replicast casting process that involves patternmaking with polystyrene and a ceramic shell mold. The article contains a table that summarizes the differences in the steps of casting a part between the permanent pattern and expendable pattern methods.

This article reviews the pattern materials used in investment casting, which can be loosely grouped into waxes and plastics. The patternmaking process, pattern tooling, and pattern and cluster assembly are described. The article also describes the manufacture of ceramic shell molds and cores, detailing the binders and other materials used, as well as the formulation and control of slurries. Methods for pattern removal, mold firing, melting, casting, postcasting treatment, and inspection are explained. After presenting design recommendations for investment castings, the article concludes with information on applications and special versions of the investment casting process.

This article reviews the basic types of mold aggregates and bonding methods for expendable molds and coremaking. It provides an overview of mold media and the basic types of sands and their properties. The most significant clays used in green sand operations, such as bentonites, are discussed. The article describes the methods of sand bonding with inorganic compounds. It provides a description of resin-bonded sand systems: no-bake binder systems, heat-cured binder systems, and cold box binder systems. The article concludes with a discussion on the media used for expendable molds, namely, ceramic shells and rammed graphite, for casting reactive metals such as titanium or zirconium.