Investment Casting From the Pyramids to the Present

Investment Casting From the Pyramids to the Present, also referred to as lost-wax casting, has been in use for over 5,000 years, from the pyramids right up to the present. The basic idea behind the process is to create a model out of wax of the object to be cast or created. In the present, other materials that have a low melt temperature may be used in place of the common wax that’s been used for millennia.

As an example, an artisan might sculpt a little statue of a cow out of wax, taking care to detail around the eyes, hooves and horns. The wax model is then covered by the material that will create a mold, as described below.

Investment Casting from the Pyramids to the Present - 1: Once the model is created it is then covered with plaster or sand to create a mold of the model. After the mold has set, it is placed in a kiln or oven and heated to a high enough temperature to melt the wax, which flows out of the mold and is “lost”, thus the reason for the term “lost wax casting.” This leaves a hollow in the exact shape of the original wax model; in this example, the wax cow.

Instead of the beeswax that was employed in ancient Egypt, new materials are used that can hold a more intricate modeling, yet melt just as easily. This allows the creation of items that require a certain degree of precision and accuracy. This has made it extremely valuable in producing items for some of the most demanding industries.

It was actually during World War II that investment casting came into it’s own for use in modern manufacturing. Today not only is the process vital to the aerospace and automotive industries, but is used by medical and dental instrumentation manufacturing, sports industries and a variety of other industries.

Investment Casting from the Pyramids to the Present - 2:There is another process that instead of creating one piece at a time, which is very time-consuming and not cost-effective, creates a mold with multiple “cavities”. One type of this multi-model mold is a “tree”. Multiple models are attached on a “tree” which is then dipped in a silicate slurry and then into sand. Once it has dried, the process is repeated until the correct thickness of the mold is achieved.

Then the tree is heated in a furnace, kiln or other high-temperature oven. The mold hardens, while the wax used to create the models melts. What is left is a single-use strong mold that will produce an exact replica of the model.

Investment Casting from the Pyramids to the Present - 3 :The mold can then be filled with a metal or metal alloy that has been heated to a liquid form. After the metal has cooled the hardened slurry mold will then be broken off revealing a precise replica of the original model.

The entire lost wax casting process does span a time frame that takes investment casting from the pyramids to the present





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