1. Mold making. A wax mould is made according to the CAD system.
2. Wax Model-making. Molten wax is poured into the mould and formed
a model that exactly same shape as the cast part.
3. Wax assembly. The wax patterns are connected to the runner
system by hot knife according to certain rules. When this finish, a
pattern tree is ready.
4. Slurry. The wax pattern tree is dipped into a slurry of silica,
then into a sand-like stucco, or dry crystalline silica of a
controlled grain size. The slurry and grit combination is called
ceramic shell mould material, although it is not literally made of
ceramic. This shell is allowed to dry, and the process is repeated
until at least a half-inch coating covers the entire piece. The
bigger the piece, the thicker the shell needs to be.
5. Burnout. The ceramic shell-coated piece is placed cup-down in an
autoclave, who hardens the silica coatings into a shell, and the
wax melts and runs out. This process makes hollow in the shell
where formerly occupied by the wax.
6. Pouring. The shell is preheated in the clave to harden the
patches and remove all traces of moisture, then placed cup-upwards
onto a sand bed. Metal is melted in a furnace, then poured
carefully into the shell. The shell has to be hot because otherwise
the temperature difference would shatter it. The filled shells are
then allowed to cool.
7. Release. The shell is hammered or sand-blasted away, releasing
the rough casting. The gates, which are also created in metal, are
8. Machining and finishing. The casting is shot blasted and then
machined to required tolerance if necessary. Further finish like
plating or polishing can also be operated according to customer