A pattern of the component to be cast is produced by injection molding special waxes into a metal die. Pre-formed ceramic cores or water-soluble wax cores can be included in the wax patterns as it is molded, which can create intricate hollows within the finished casting As many as several hundred patterns may be assembled into a tree around a wax runner system (riser & sprue).

The completed tree is dipped, or invested, by hand or via robotic control into a ceramic slurry of ethyl silicate (alcohol-based and chemically set), colloidal silica (water-based, also known as silica sol, set by drying) or a hybrid of these controlled for pH and viscosity. Our facility uses water-base. A fine sand is applied to the invested tree in a fluidized bed, rain tower sander, or by hand. During the primary coat(s), the sand will typically be a zircon-based, as zirconium is less likely to react with molten metal when poured into the shell. The stuccoed tree is then allowed to dry before re-dipping in slurry and applying secondary coats of mullite, Molochite, chamotte or fused silica refractory material. This process is repeated until the shell is thick enough to withstand the mechanical shock of the receiving the molten metal. Dry times generally range from 24 to 48 hours, and total production from two days to one week.

After the shell has been constructed, the wax is removed in an autoclave or furnace (hence, the lost-wax process). Most shell failures occur at this point, as the fragile stuccoed shell is subjected to extremes of temperature and, in an autoclave, pressure. The shell is then fired at temperatures of around 1,100 degrees Celsius to induce chemical and physical changes in the set refractory materials forming a ceramic shell. This leaves a ceramic impression of the part to be cast. Most foundries remove the shells from the furnace wile still holt and pour the molten metal into the ceramic shell. Various methods of pouring the molten metal include vacuum casting, anti-gravity casting, tilt casting, gravity pouring, pressure assisted pouring, centrifugal casting. Our facility is strictly gravity. After the molten metal cools, the shell is removed. This is generally done with water-jet, vibration, grit blasting or chemical dissolution. The cooled parts are removed from the tree by sawing them off (by hand, band, friction, or fiber wheel), breaking them off (by designed gating or liquid nitrogen). The castings (parts) are then finished.

VIEW ILLUSTRATED INVESTMENT CASTING PROCESS