Sand casting uses a refractory material in the form of small grains that can take on the desired complex shape that is fixed following the use of an additive. The sand mould is single-use, but can easily be made repeatedly.
The material is poured into a sand mould, which is destroyed after the production of each piece. The sand mould is made in one or more parts: each part has an imprint with the shape of the piece traced by a model (made of wood, metal, etc.) embedded in the sand. When the piece has internal shapes (holes, recesses, etc.), a sand core is inserted into (between) the part(s) of the mould, which will be held there (in the mould) and then destroyed after the piece has been removed from the mould.
For these types of moulds, SIAF designs and manufactures the models and shells of the cores.