Sand casting, also known as sand molded casting, is a metal casting processes incorporating the use of sand as the mold material of choice. A sand casting foundry undertakes the production of these types of products, with an estimated 70% of all metal castings being produced via a sand casting process.
Very simply put, there are six basic steps in this type of casting process. First, pattern is placed in the sand to create a mold, followed by the incorporation of the pattern and the sand in what is called a gating system.
From here, the pattern is removed, the mold cavity is filled with the molten metal of choice and the allowed to cool and solidify. Finally, the sand mold is broken away and the final casting remains.
Green & Resin Sand Casting Green sand casting offers a cost-effective route and is the most traditional sand casting processes. This renders it a common choice amongst manufacturers and project leads. The material used is sand that’s bonded by water and clay—and best of all, it’s recyclable.
In the resin sand casting process, resin and sand are first mixed together. Following that, the mixture is self-hardened through chemical reaction to produce exceptionally hard molds.
Lost Foam Castings Lost foam casting is another investment casting method that differs from lost wax casting. The Lost Foam casting process was first started in year 1958 when H.F. Shroyer was granted a patent for a cavity-less casting method, using a polystyrene foam pattern embedded in traditional green sand. The polystyrene foam pattern left in the sand is decomposed by the poured molten metal. The metal replaces the foam pattern, exactly duplicating all of the features of the original pattern. Like water glass investment casting method, a pattern is required for pouring in casting, because it is evaporated (“lost”) in the process.
Shell Mold Sand Casting Shell mold casting is a metal casting process similar to sand casting, in that molten metal is poured into an expendable mold. However, in shell mold casting, the mold is a thin-walled shell created from applying a sand-resin mixture around a pattern. The pattern, a metal piece in the shape of the desired part, is reused to form multiple shell molds. A reusable pattern allows for higher production rates, while the disposable molds enable complex geometries to be cast.
The Advantages of Sand Casting
The materials used in the process itself are relatively inexpensive and are also able to resist deformation during heating and capable of holding its required detail. This process is capable of producing small, precision parts as well as large parts. Learn more about this by visiting our Ultra Large Sand Casting page. The sand casting process can be used to cast both ferrous and non-ferrous metals. When compared to other metal casting processes, the time required to prepare the mold is relatively short. This metal casting process is capable of handling a more diverse range of products when compared to other casting processes. When a uniform compaction is achieved, the sand casting process is capable of producing extremely close tolerances. The sand used in the process can be reclaimed, helping to reduce the waste produced by the sand casting foundry. The sand casting process is relatively simple, making it a great process for mechanization.