History of Investment Casting

Investment casting dates back thousands ofyears. Its earliest use was for idols, ornaments and jewelry, using naturalbeeswax for patterns, clay for the moulds and manually-operated bellows forstoking furnaces. Examples have been found around the world: from Mexico toMesopotamia, and Egypt to Africa where the investment casting process produceddetailed artwork of copper, bronze and gold.

The earliest known text that describes theinvestment casting process (Schedula Diversarum Artium) was written around 1100A.D. by Theophilus Presbyter, a monk who described various manufacturingprocesses, including the recipe for parchment. This book was used by sculptorand goldsmith Benvenuto Cellini (1500 – 1571), who detailed in hisautobiography the investment casting process he used for the Perseus and theHead of Medusa sculpture that now stand in the Loggia dei Lanzi in Florence, Italy.

Investment casting came into use as amodern industrial process in late 19th century, when dentists began using it tomake crowns and inlays, as described by Dr. D. Philbrook of Council Bluffs,Iowa in 1897. Its use was accelerated by Dr. William H. Taggart of Chicago,whose 1907 paper described his development of a technique and formulated a waxpattern compound of excellent properties, developed an investment material, andinvented an air-pressure casting machine.

In the 1940s, World War II increased thedemand for precision net shape manufacturing and specialized alloys that couldnot be shaped by traditional methods, or that required too much machining.Industry turned to investment casting. After the war, its use spread too manycommercial and industrial applications that used complex metal parts.

Modern investment casting techniques stemfrom the development in the United Kingdom of a shell process using waxpatterns known as the Investment X Process. This method resolved the problem ofwax removal by enveloping a completed and dried shell in a vapor degreaser. Thevapor permeated the shell to dissolve and melt the wax. This process hasevolved over years into the current process of melting out the virgin wax in anautoclave, or furnace.