Investment casting (also known as lost wax investment casting) produces parts with fine detail and excellent as-cast surface finish. Investment castings are formed into internal or external features, thin walls and internal channels to achieve near net shape. These features often result in significant savings in material, labor and machining costs compared to other metal casting processes.

In investment casting, a detailed wax model of the finished part is created and mounted on a wax "tree" that includes a metal delivery system (gates and risers). Alternately dip the tree in ceramic grout and sprinkle with stucco material, then allow to dry. Repeat this process until a thick crust appears on the wax mold.

The wax mold is then melted, leaving a mold-shaped cavity within the stucco material. The molten metal is poured into the cavity. Once the metal solidifies, the shell is broken through a shakeout process and the casting material is removed, leaving the finished product.

When to use investment casting
Existing external shapes and tight tolerances
Part shape or asymmetry with fine details
Multiple and/or complex internal passages in the design
Small to medium size, typically under 1,000 lbs/454 kg
Requires excellent as-cast surface finish
The wall thickness of sand casting is too thin
Higher up-front tooling costs are acceptable relative to sand casting
Low throughput allows printing patterns to replace up-front tools
No ongoing tool maintenance costs
Unable to machine internal channels