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Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand—known as casting sand—as the mold material. The term "sand casting" can also refer to an object produced via the sand casting process. Sand castings are produced in specialized factories called foundries. In 2003, over 60% of all metal ...
In the simplest sand casting procedure, the drag is placed upside down on a board, around a pattern of the part to be cast. The pattern is a model of the desired casting. Talcum powder is often dusted over the pattern to aid in the removal of the pattern. Sand is sifted over the pattern until the model is covered by a few inches of sand.
Sand casting is one of the earliest forms of casting practiced due to the simplicity of materials involved. It still remains one of the cheapest ways to cast metal because of that same simplicity. Other methods of casting, such as those using shell molds , boast higher quality of surface finish but have a higher cost.
For the production of gray iron, ductile iron and steel castings, sand casting remains the most widely used process. For aluminum castings, sand casting represents about 12% of the total tonnage by weight (surpassed only by die casting at 57%, and semi-permanent and permanent mold at 19%; based on 2006 shipments). The exact process and pattern ...
A molding sand mixture, usually green sand or bentonite, is blown into a rectangular steel chamber using compressed air. The molding sand is then squeezed between two patterns, which are on the two ends of the chamber. After squeezing, one of the chamber plates swings open and the opposite plate pushes the finished mold onto a conveyor.
A bronze casting showing the sprue and risers. A riser, also known as a feeder, [1] is a reservoir built into a metal casting mold to prevent cavities due to shrinkage.Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify.
A template is prepared (typically made of wood, or a found object or even a body part such as a hand or fist) which is tightly pressed into the sand to make a clean impression. This impression then forms the mould. The surface of the mould can be covered in coloured glass powders or frits to give a surface colour to the sand cast glass object.
Permeability is a property of foundry sand with respect to how well the sand can vent, i.e. how well gases pass through the sand. And in other words, permeability is the property by which we can know the ability of material to transmit fluid/gases. The permeability is commonly tested to see if it is correct for the casting conditions. [1]