Skalstøbning

Skalstøbning, also known as ceramic shell casting, is a metal casting process that uses a thin, precision ceramic shell formed around a pattern to reproduce complex geometries with a smooth surface finish. The method combines aspects of investment casting and shell molding to produce accurate, near-net shapes suitable for a range of metals.

The process begins with a pattern, typically made of wax or plastic, mounted on a sprue assembly. The pattern is repeatedly dipped into a ceramic slurry and then coated with a refractory ceramic material (stucco) to build up multiple thin layers. Each layer is dried before the next is applied. After the desired shell thickness is achieved, the assembly is fired in a kiln to burn out the pattern and harden the ceramic shell. Molten metal is then poured into the hollow ceramic shell, which is subsequently broken away to reveal the cast part. Finishing steps such as heat treatment, grinding, and surface finishing complete the process.

Materials used include petroleum or wax patterns, silica- or alumina-based ceramic slurries, and refractory binders. The technique is commonly applied to small- to medium-sized parts that require high dimensional accuracy and excellent surface quality, including components for automotive, aerospace, jewelry, and tooling industries. Alloys often cast by this method include aluminum, steel, bronze, and nickel-based alloys, depending on shell properties and equipment.

Advantages of skalstøbning include tight tolerances, superior surface finish, and good reproduction of complex features. Limitations involve higher tooling and equipment costs, longer cycle times, and shell brittleness, making it less suitable for very large parts or low-value production. See also investment casting and ceramic shell process.