What are aluminum sand castings?

Aluminum sand casting process

Aluminum sand casting is a metal casting process where sand is used to mold material together.

Currently, a majority of metal castings are produced by the sand casting process. This is largely because aluminum sand casting is a very cheap and effective means of molding material together.

Sometimes for increased durability, the sand will be mixed with clay. This mixture will moisten when added with water, and then strengthen when it dries afterward. This makes it much more suitable for molding.

However, clay does not always need to be used for this method. Sometimes one method that is used for aluminum sand casting method is the air set method. When the air set method is utilized, an adhesive material other than clay is most often used.

How the aluminum casting process works

But regardless of the method that is used, aluminum sand casting should result in a mold cavity being formed. These air set molds can be formed using a casting flask that has both a bottom and a top part.

sand casting process diagramNext, the sand mixture is pressed together around the pattern of the mold cavity. The final part of the assembly will often require the sand to be vibrated in order to eliminate any holes or empty spaces in the mold. The casting liquid is ultimately what is poured into the mold cavity, and once the metal has cooled off and become solid, the casting can be finally divided from the sand mold. The mold will be subsequently destroyed.

The quality of the casting itself is almost entirely dependent on how well the molding process was completed, and the type of sand mixture that was used. Much of the sand castings that are made using green sand will deliver a rough texture. Green sand for aluminum will generally use olivine sand.

The end result and aluminum cast part finish

Air set molds will produce castings that typically have a smoother surface than green sand, but this can also be a more expensive means than green sand as well, and as a result are only used when a smooth pattern is necessary. Air set castings will also give a burned color to the surface of the mold, and will require treatment afterward in order to remove the burned color.

Fortunately, all this treatment will usually require is a good polishing. However, if this doesn’t work, grinding or shot blasting are alternative means as well. All in all, green sand for aluminum is a good way to go, as it generally won’t require this type of treatment once it has been molded.

While the sand is being cast, much of what was in the sand mixture will be lost during the casting process.

However, green sand when used for aluminum can be used again to refill the moisture that was lost, meaning that it can also be used to make new molds. This is why that aluminum casting process is one of the most effective means of sand casting, and is used very often on the production lines in factories.