Investment casting and ceramic shell

This process is used to produce intricate, thin section parts with high dimensional accuracy, fine details, and very smooth surfaces. 

The wax patterns are cleaned with water or organic solvent and coated with a wetting agent, which helps the ceramic slurry to adhere to the wax. The cluster is then dipped in a liquid ceramic slurry, stuccoed with granular silica, zircon or alumina/silica refractories and then dried before the application of the next coat. The coating process is continued until a sufficiently thick shell is established. 

The dried mould is then de-waxed by inserting it into a steam autoclave in which the wax patterns are melted out, or into a flash-furnace , in which the wax may be partially burnt out. 

After this, the shell is fired in a fiimaee at a high temperature. This bums out the residual wax and hardens the eeramic, leaving a one pieee eeramie shell mould, into which the molten metal is poured to form the casting. 

In this process, air pollution may occur during two operations investing and de-waxing. 

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