Investment Casting :
Wax Mold

The origins of the lost wax process are shrouded in antiquity, but it has been used for thousands of years to produce objects in metal which could not be produced any other way, due to the complexity of their form. It permits anything that can be modelled in wax to be faithfully transmuted into metal, and is still used today for certain industrial parts, dental restorations, fine jewelry, and sculpture.

While wax patterns were originally modelled by hand, and this can still be done, it is now possible to cast wax into molds as well, so that multiple copies may be made even though the wax pattern is lost in the process. Modern synthetic rubbers have been developed which capture very fine detail and can flex to release undercut areas of a model, greatly reducing the number of mold parts and the number of parting lines necessary, when compared to the earlier technique of using wet plaster molds. Waxes can be cast either solid or hollow, as the wax will coat the inside of a mold after it is filled and poured out. This process is repeated to build up the desired thickness of wax. The process is slightly different for jewelry and sculpture; the smaller quantities involved when making jewelry-sized pieces necessitate some adaptations to overcome the effects of surface tension, such as wax injection instead of simple pouring, and the use of a vacuum table or centrifugal casting machine to force metal into molds.