Good casting can be determined by the pattern and the types of molding sand used. One needs to understand the types of molding sand used in casting in order to perfectly create objects. Today you’ll get to know the various types of sand used in casting and how they work.
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Types of molding sand used in casting
The following explained below are molding sand used for casting:
these types of molding sand are natural sand with enough moisture in them. It contains clay of about 15 to 30%, 8% of water, and silica. The clay and water act as binding materials that gives strength to the mold. it is used only for simple and roughcasting. It is used for both ferrous and non-ferrous metals.
This casting sand is obtained when the moisture from green sand is removed. It is used for large and heavy casting because the molding sand offers greater strength, rigidity, and thermal stability to the casting.
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as the name implies, facing sand is used for facing the mold. it consists of fresh silica sand and clay. That is, no used sand is added. It is used directly next to the surface of the pattern. Facing casting sand must have high refractoriness and strength because it comes in direct contact with the hot molten metal. These types of molding sand give the mold a very fine grain.
Core molding sand types contain silica sand mixed with core oil (linseed oil, resin, and mineral oil) and other binding materials like dextrin, cornflour, and sodium silicate. It is used for cores making and has high compressive strength.
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Loam sand is an equal mixture of sand and clay with a sufficient amount of water added to it. It is also used for large and heavy molding like hoppers, turbine parts, etc.
These types of molding sand are pure silica sand poured on the faces of a pattern before molding. Parting sand is sprinkled on the pattern before it is embedded in the molding sand. This casting sand is also sprinkled on the contact surface of cope, drag, and cheek.
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Backing and floor sand:
This casting sand is used to back up the facing sand and to fill the volume of the box. It is also known as floor sand.
This molding sand is applicable to mechanical heavy castings. It has high strength, permeability, and refractoriness. System sand is used for machine molding to fill the whole flask. Facing sand is not used in this molding because cleaned and has special additives.
This molding sand is also used for core making and small casting of intricate shapes. It contains molasses as its source of binding.
And that is all for this article, where types of molding sand (casting sand) are explained. I hope you gain a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!