Evaporative Aluminum Casting

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Introduction[edit | edit source]

Evaporative casting consists of using low temperature organic solids as molds in the casting process. Such solids can usually be easily transformed and allow for the creation of quick, high-precision molds. Such a mold is usually embedded within sand, and then proceeds to have molten aluminium poured into it. The aluminium takes the shape of the mold, and also evaporates it. 3D printers in particular have brought a new way of creating rapid high-accuracy molds.

Mechanics[edit | edit source]

As a molten metal is poured into the mold, the heat from the metal causes the low-temperature organic solid to generally either decompose, or evaporate. The gases given off during such casting procedures are generally toxic because of this.

Methods[edit | edit source]

Here, you can see the defects from the casting process and the low-resolution surface finish.

Pink foam board insulation- Easy to carve, this mold material is usually cheap and easy to acquire. However, due to its extremely rapid decomposition under high temperatures, the sand or filling material around the mold can cave in before the molten aluminium reaches the correct locations.

In contrast, the detail here is much more profound. The finish is consistent in color and also in porosity. (ie. minimal)

Polystyrene- Polystyrene can be easily carved with a hot-wire knife, and is also cheaply available. However, it has the same rapid decomposition properties as the pink foam board insulation.

3D printed PLA- 3D printers are becoming more readily accessible every day, making them a viable option. Here now, the problem comes with the toxicity of the decomposing plastics as they are introduced to the temperature of the molten aluminium

3D Printed dissolvable filament (UNTESTED)- In this case, dissolvable filament can be used to make the mold, which can then be quickly painted with plaster of Paris. This creates a rapid mold which doesn't produce ghastly fumes, but is still as high of a resolution as PLA.

This links to a video outlining and demonstrating evaporative casting techniques using pink foam board insulation, and 3D printed parts. www.youtube.com/embed/P6mgyYQO-1I

References[edit | edit source]