What types of casting molds can I use for aluminum?

When it comes to aluminum casting molds, there are quite a few options available, however, some of these options may not be as feasible to some, especially if they are working on these projects from home without a dedicated shop or foundry.

Some of the most common casting molds for aluminum casting include:

Sand Casting Molds: Sand Casting Molds are created by a process of using sand as the mold material, normally mixed with some type of bonding agent like clay, for example. This mixture is kept moist, which allows it to develop strength and plasticity, making it suitable as a mold. A box or, “flask” holds the sand in place, a cavity is then created within the sand, and the molten metal (aluminum in our case) is poured in.

Shell Casting Molds: A Shell Casting Mold is a type of sand-casting mold but uses resin to bond the sand. This process provides better dimensional accuracy than traditional sand casting and is great for parts requiring high precision. This casting ends up having very thin walls (about 10mm to 20mm thick) which helps give it it’s precision.

Die Casting Molds: Die Casting Molds are made of steel and are great when you need multiple of the same parts. It is a versatile mold that allows for the production of large amounts of small and medium aluminum castings.

Ceramic Casting Molds: Ceramic Casting Molds are created around wax that melts when the mold is fired. The wax melts away and is “lost” (a process known as lost wax casting) Once the wax is lost, the molten metals, like aluminum, can be poured. Very precise casts can be made with this mold.

Plaster Casting Molds: Plaster Casting Molds are very similar to sand castings, however, they can only be used with non-ferrous metals like aluminum. Plaster molds also use the “lost wax casting” process, just like Ceramic Casting Molds.

Graphite Casting Molds: Graphite Casting Molds are sometimes categorized as permanent, dependent on the quality and production of the graphite. The graphite casting process forces the molten metal, such as aluminum, through the mold. The mold and cast are rapidly chilled, and it produces a high-quality cast.

Silicone Casting Molds: Silicone Casting Molds are a unique way of creating a mold for metal casting. It is a very simple way to create a mold from an object. Silicone molds are best used for low melting point metals, however, for smaller castings, such as jewelry, metals of higher melting point may be able to be used.

Not all casting molds are reusable, and some that are, may not be feasible for the typical at home, casting enthusiast, but here are some options for you to use when trying to make a reusable casting mold for aluminum.

Permanent Casting Molds: Permanent Casting Molds are usually made from metals like steel and iron. The greatest benefit of these is that they are reusable. The downside, having the mold created will cost money, because it is likely you would have to get the mold created by a foundry, a machine shop, or have/create your own foundry (which can be quite an undertaking).

Graphite Casting Molds: Another good mold for at home casting for aluminum is Graphite Casting Molds. As at home casting grows in popularity, so do the solutions for expensive and hard to find molds. There are many art and craft suppliers selling pre-made graphite molds, as well as graphite blocks for you to carve your own designs.

Silicone Casting Molds: Silicone Molds for casting aluminum may be a bit of an experiment. Because the melting point of aluminum is higher than silicone, quite often silicone molds can burn or be destroyed. We would suggest that if you would like to try using a silicone mold for aluminum, to start with small molds, like jewelry or coins. The quality of silicone you use can play a part in determining the quality of casting you will produce.

In Conclusion

Aluminum Metal Casting at home can be quite an exciting experience. It is a great activity for those who have experience with metal casting in the past. If you do not have any experience and would like to pursue this activity, we recommend that you learn from someone who has experience metal casting, read various books on the process, and watch numerous videos on the internet. Molten metal can be highly dangerous and can cause serious accidents, so it is important you do your due diligence before attempting your own pour.