What is Investment Casting?
Investment casting / precision casting or the “lost wax” process has been in use since the construction of the first pyramid. The Egyptians and Chinese used the process in their early history to make jewellery and statues. The investment casting method was largely ignored as an industrial process for the fabrication of parts until the demand for rapidly finished parts during World War II created the need for “near net-shape” components that could readily be put into their final form. At this time new inorganic high temperature ceramic mold binders were developed to industrialize the process applications to include high strength and corrosion resistant materials such as low to high carbon alloy steel, tool steel, stainless steel, and nickel and cobalt base alloys. Aluminum and brass alloys are available also.
It is a process capable of producing intricate shapes weighing from a small fraction of an grams up to 20 Kg. or more. Some examples would be: aircraft structural parts, components for the automotive industry, military weaponry, jet engines, machinery components, dental appliances, jewelry and many others.
In general, an injection molded wax pattern is used for each part produced which is then encased in multiple layers of ceramic material. The wax pattern is then removed from the ceramic shell mold. The mold is fired in an oven and then molten metal is poured into the cavities left by the evacuated wax pattern. Upon cooling, the resulting precision casting are cleaned and subjected to further processing such as heat treatment. At this point, many parts are in their final form and are ready for use while others may require a small amount of further processing such as machining before reaching their final form.