lostwax

Lost-wax casting, also known as investment casting, is a metal casting process in which a wax pattern is enclosed in a refractory ceramic mold. After the mold is set, the pattern is heated to melt and drain away the wax, leaving a hollow cavity into which molten metal is poured. The ceramic shell is broken away after solidification to reveal the finished part.

Typical steps include creating a wax pattern or assembly, attaching it to a sprue, investing the pattern in ceramic material, curing the investment, dewaxing by burnout, preheating the mold, pouring metal, allowing the piece to cool, and finally divesting the ceramic and finishing the part.

Origins date to ancient civilizations such as Mesopotamia and Egypt, with later prominence in Greek and Etruscan art. In the modern era the method was refined for precision jewelry and industrial parts, and today it is widely used in aerospace, automotive, dental, and sculpture applications.

Materials and variants include wax patterns (including those produced by 3D printing), plaster or ceramic investments, and metals such as bronze, brass, stainless steel, aluminum, nickel-based alloys, and titanium. Process variants include ceramic-shell and gypsum-based investments, with 3D pattern generation increasingly common.

Advantages include the ability to reproduce complex geometries and achieve excellent surface finish and dimensional accuracy for small to medium production runs. Drawbacks are high tooling and material costs, longer cycle times, and sensitivity to defects during wax pattern fabrication or burnout.