Sand casting

The sand molding process belongs to the casting process of the lost form.

A foundry model ( eg of wood, metal or clay ) is shaped in this "sand" ( as the molding material ), the model is removed and poured the remaining cavity with the molten material (eg, metals). The metal flow due to its own weight by a system of supply lines ( the gate system ) facilitates the " Dump ", a system of exhaust channels, in some cases, the escape of the gases out of the cavities. The production of parts with complicated geometries (including cavities ) and different material cross-sections with the appropriate knowledge and experience ( specific to the material), only by this method represented, which owes its name to the former base molding material of foundry sands.

Development

Sand casting is in the casting production by casting method for larger quantities with gravity casting ( permanent mold ) and was supplemented for rotationally symmetric geometries with centrifugal casting. An exception forms for example the bell-casting, in which the forms would be too big for a centrifugal casting. A vast variety of castings of all sizes and materials is made thanks to this technology with sand casting, for example, cylindrical rollers, steam turbine casings, etc.

In order to stabilize the sand ( molding material ), it requires a binder, eg, clay (bentonite ) with the appropriate amount of water (wet casting or sand casting ) or oil, water glass with CO2 or cold resin ( furan ).

Sand molds (with molding material quartz, chromite, zircon, etc.) or were used among other things for bell-casting and art casting and are prevalent throughout the foundry industry for the manufacture of metal mold castings. The traditional concept of Sand is replaced in the modern usage of foundry technology by the technical term mold material, since the materials used have little in common with naturally occurring raw materials for Gießformherstellung.

If the sand mold was prepared with a model, which burns when pouring in the form ( gassed ), one speaks of the lost foam casting with a lost form, since these sand mold must be destroyed when emptying the cooled casting.

Application in the Food Industry

A comparable with the sand molding process is used for shaping of fruit gums. Here, a model of the form is pressed into a layer of corn flour. In the resulting deepening the hot fruit jelly material is packed and stored until it has cooled. Then, the sweets are separated by sieving from corn flour and packaged. Through the use of corn flour the fruit gums also do not stick as much to each other.

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• Metallurgy
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