Investment Casting
WAX PATTERN INJECTION
The process begins with production of a one-piece heat-disposable patterns or die. These patterns are generated from wax by utilizing an aluminum wax injection mold for production lots. Prototype of the pattern can be made with the help of CAD using various resins and polymer.
WAX PATTERN ASSEMBLY
Several patterns are assembled by sticking them on to wax bars called Runners or Sprues, to form a cluster. The assembly is also called as tree.
CERAMIC SHELL BUILDING
The Wax Assembly is dipped into a refractory slurry, drained and then covered with ceramic grain. The process of dipping and coating is repeated several times, depending on the size and configuration of the component, to create several layers giving the required thickness of coating.
REMOVAL OF WAX
The removal of wax is then achieved by placing the wax tree in a high temperature and pressure vessel. The high temperature melts the wax inside the ceramic shell and the pressure forces it to run out through the runner system. After removal of the wax, the resulting hollow "Mould Shells" are pre-heated in a Shell Pre-heating Furnace to make them strong enough to withstand the metal pressure, when hot liquid metal is poured into the shell.
CASTING OF PARTS
The casting of the part is accomplished by pouring molten metal into the preheateds ceramic hell. As the metal cools it solidifies into the shape of the cavities left behind in the ceramic shell.
CERAMIC SHELL REMOVAL
The individual cast are cut-off from the cluster, using an electric arc or a gas flame or an abrasive disc. The runner system is melted again to be poured into other ceramic shells.
FINISHING
The process of finishing involves cutting or grinding off of unwanted portions, followed by thorough cleaning and finishing. Different process of finishing are used to give the required surface finish and dimensional accuracy.