Ceramic Shell Making

After the completed wax assemblies are produced and cleaned, a ceramic shell is produced by repeatedly dipping the wax assembly first in a liquid ceramic slurry followed by coating with ceramic stucco.

A fully automatic "Shellmaking" robotic system is employed to invest the assemblies. A number of coats are applied until the "Investment Shell" is thick enough to withstand the thermal stresses of pouring.

The pattern tree is attached to the robotic arm of a 'Shellmaker' system and dipped and rotated in a vat of thin refractory slurry. After draining, fine grains of refractory are deposited onto the damp surface, providing a primary refractory coating. 

The primary coat typically contains a zircon based refractory combined with water based (silica sol) binders. Alcohol-based binders (ethyl silicate) can also be used though these are not as environmentally friendly. 

Click here to view a ceramic shell making video.

When the primary coat has hardened in an air drying room subsequent cycles of 'wet' dipping and dry 'stuccoing' build up the thickness of the invested material to provide a refractory shell that, when fully hardened, is sufficiently strong to hold the liquid metal during casting.

Next Stage: Wax removal.