Molding sand

Molding sand

Molding sand, foundry sand, or green sand is sand that when moistened or oiled tends to pack well and hold its shape. It is used in the process of sand casting.

Green sand

Green sand is an aggregate of sand, bentonite clay, pulverized coal and water. Its principal use is in making molds for the casting of metals. The largest portion of the aggregate is always sand, which can be either silica or olivine. There are many recipes for the proportion of clay, but they all strike different balances between moldability, surface finish, and ability of the hot molten metal to degas. The coal, typically referred to in foundries as sea-coal, which is present at a ratio of less than 5%, partially combusts in the presence of the molten metal leading to offgassing of organic vapors.

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 metals because of that same simplicity. Other methods of casting, such as those using shell molds boast higher quality of surface finish, but higher cost.

Green sand (and other casting sands) is usually housed in what casters refer to as flasks which are nothing other than boxes without a bottom or lid. The box is split into two halves which are stacked together in use. The halves are referred to as the top (cope) and bottom (drag) flask respectively.

Green sand is not green in color, but "green" in the sense that it is used in a wet state (akin to green wood). According to the Cast Metals Federation website, an alternative casting method is to heat-dry the molded sand before pouring the molten metal. This dry sand casting process results in a more rigid mold better suited to heavier castings.

ee also

* DISAMATIC
* Foundry
* Casting
* Sand casting
* Cope and drag
* Hand mould


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  • molding sand — noun : a mixture of sand and clay suitable for making foundry molds …   Useful english dictionary

  • Sand casting — Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand as the mold material. It is relatively cheap and sufficiently refractory even for steel foundry use. A suitable bonding agent (usually clay)… …   Wikipedia

  • Molding — Mold ing, Moulding Mould ing, p. a. Used in making a mold or moldings; used in shaping anything according to a pattern. [1913 Webster] {Molding board} or {Moulding board}. (a) See {Follow board}, under {Follow}, v. t. (b) A board on which bread… …   The Collaborative International Dictionary of English

  • Molding board — Molding Mold ing, Moulding Mould ing, p. a. Used in making a mold or moldings; used in shaping anything according to a pattern. [1913 Webster] {Molding board} or {Moulding board}. (a) See {Follow board}, under {Follow}, v. t. (b) A board on which …   The Collaborative International Dictionary of English

  • Molding machine — Molding Mold ing, Moulding Mould ing, p. a. Used in making a mold or moldings; used in shaping anything according to a pattern. [1913 Webster] {Molding board} or {Moulding board}. (a) See {Follow board}, under {Follow}, v. t. (b) A board on which …   The Collaborative International Dictionary of English

  • Molding mill — Molding Mold ing, Moulding Mould ing, p. a. Used in making a mold or moldings; used in shaping anything according to a pattern. [1913 Webster] {Molding board} or {Moulding board}. (a) See {Follow board}, under {Follow}, v. t. (b) A board on which …   The Collaborative International Dictionary of English

  • Sand — For other uses, see Sand (disambiguation). Close up of sand from the Gobi Desert, Mongolia, showing a surface area of 1 square centimetres …   Wikipedia

  • Moulding sand — Molding Mold ing, Moulding Mould ing, p. a. Used in making a mold or moldings; used in shaping anything according to a pattern. [1913 Webster] {Molding board} or {Moulding board}. (a) See {Follow board}, under {Follow}, v. t. (b) A board on which …   The Collaborative International Dictionary of English

  • sand casting or sand molding —    A method of casting in metal in which a mold is made by firmly packing layers of very fine damp sand around a sculpture. When the original is removed an exact impression is left in the sand. The more complex is the form to be cast, the more… …   Glossary of Art Terms

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