Investment Casting - The Process

Investment Casting owes its' name to the application (investment) of a refractory ceramic coating to an expendable pattern. The history of the process can be traced back to 4000BC when early pattern materials included carved animal fat, leather, bees wax and other combustible materials. Examples of early investment castings are found in Europe, Asia, Africa and South America. Many of these castings are very intricate and show a high degree of craftsmanship. For much of history, investment casting was confined to sculpture and works of art. The development of the process to manufacture medical and engineering components only occurred in the 20th century when over 400 patents were granted between 1900 and 1940.

Benin Bronze Engineering Castings Crystal Castings

Benin Bronze
c. 14C


Engineering Castings
c. 1960


D.S. & Single Crystal Castings
c. 1990

The process used today is based on expendable patterns made from mixtures of natural and synthetic waxes, which are produced by injecting into aluminium or steel dies. For prototype or low volumes it is possible to produce patterns using a number of Rapid Prototyping methods including stereolithography and selective laser sintering. Hollow components can be cast using patterns produced with water-soluble cores. When intricate internal passages are required it is usual to cast with preformed ceramic cores.

Die -->


Pattern -->


Wax pattern / runner assembly -->

Wax pattern / runner assembly

Investment shell mould -->

Investment shell mould

Cast mould -->

Cast mould

Investment Mould
Investment moulds are produced using slurries based on alumino-silicates, alumina, silica or zircon bonded with an air-dried silica sol. A series of coats are applied using slurry dips and refractory stuccoes such as alumino-silicates and alumina
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