Sand casting is a process that has been used for hundreds of years to create molds for forming metal. The metal is heated until it reaches a liquid state and then poured into the sand mold, so the sand chosen for the mold must stand up to the heat of the process.
1. Foundry Sands
There are many different kinds of foundry sand on the market, but all of them are similar in that the sand needs to have a high silica content and the grains need to be as uniform as possible so that the sand adheres to itself well and can take an extensive amount of heat. The higher the sand quality, the more uses you can get from the sand, which can save a lot of money if you are doing a lot of casting.
Metals often cast in foundry sand include aluminum, brass, copper, iron, and sometimes steel. When the molten metal is poured into the casting, It is critical that the sand not shift or burn. Sometimes a small amount of the foundry sand near the opening for the pour and the spree (the vent for gases and air) will scorch, but that small amount of sand can be sifted out of the sand to be reused.
If the foundry sand you are using is too dry, the mold could come apart during the pour and cause a failure. A failed mold can also mean molten material escaping the mold can come into contact with people or combustible, both of which are extremely dangerous. Using the highest quality foundry sand you can find is an excellent starting point for safe casting.
2. Ceramic Foundry Sand
Ceramic foundry sand is a little different than the standard sand that you might typically use. The ceramic foundry sand is bauxite sand that is heated and treated with some chemicals to create high-temperature foundry sand with precise grain sizes and can withstand far great amounts of heat than standard foundry sand.
The ceramic foundry sand is also more durable than traditional sand so that it can be reused many times with less chance of burned sand after a pour. The cost of the ceramic foundry sand is higher, but for large operations that are doing a lot of sand casting, the price is offset by the reduction in waste and the lower percentage of mold failures.
Ceramic sand also has a much lower thermal expansion rate than traditional foundry sand, meaning there is less change in the mold as you pour the metal in, creating a more precise casting that requires less clean up once the part is out of the mold.
For more information, contact suppliers who offer foundry sand or ceramic foundry sand options.