Types of sand according to size:-
GREEN SAND
DRY SAND
LOAM SAND
FACING SAND
BACKING SAND
SYSTEM SAND
PARTING SAND
CORE SAND
Define all types SAND:_-
GREEN SAND- It is a mixture of silica sand with 18 to 30 percent clay, having a total water content 6 to 8 percent. The clay and water furnish the bond for green sand. It is fine, soft, light, and porous. Being damp when squeezed in the hand, it retains the shape, the impression given to it under pressure. Moulds prepared in this sand are known as green sand moulds.
DRY SAND- Green sand that has been dried or baked after the mould is made is called dry sand. They are suitable for larger castings. Moulds prepared in this sand are known as dry sand.
LOAM SAND- Loam Sand is high in clay, as much as 50 percent or so, and dries hard. This is particularly employed for laom moulding usually for large castings.
FACING SAND- Facing sand forms the face of the mould. It is used directly next to the surface of the pattern and it comes into contact with the molten metal when the mould is poured. Consequently, it is subjected to the the severest conditions and therefore, must possess, high strength and ls with refractoriness. It is made of silica sand and clay, without the addition of used sand. Different forms of carbon are uscd to prevent the metal from burning into the sand. They are sometimes mixed with 6 to 15 times as much fine moulding sand to make facings.
BACKING SAND- Backing sand or floor sand or floor sand is used to back up the facing sand and to fill the whole volume of the flask. Old, repeatedly used moulding sand is mainly employed for this purpose.
The backing sand is sometimes called black sand because of the fact that old, repeatedly used moulding sand is black in colour due to the addition of coal dust and burning on coming in contact with molten metal.
SYSTEM SAND-In mechanical preparation and handling unit, no facing sand is used. The used sand is cleaned and reactivated by the addition binder in of water binders and special additives. This is known as system sand, In etimes mechanical foundries, where machine moulding is employed so called system sand is used to fill the whole flask. Since the whole mould is made of this system sand therefore, strength, permeability and refractoriness of this sand must be higher than those of backing sand.
PARTING SAND-Parting sand is used to prevent the green sand from sticking to the pattern and also to allow the sand on the parting surface of the cope and drag to separate without clinging. This is clean clay-free silica sand which serves the same purpose as parting dust
CORE SAND- Sand used for making cores is called core sand sometimes called oil sand. This is silica oil sand. This is silica sand mixed with core oil which is composed of linseed oil, resin, light mineral oil and other binding materials. Pitch or flours and water may be used in larger cores for the sake of economy.
GREEN SAND
DRY SAND
LOAM SAND
FACING SAND
BACKING SAND
SYSTEM SAND
PARTING SAND
CORE SAND
Define all types SAND:_-
GREEN SAND- It is a mixture of silica sand with 18 to 30 percent clay, having a total water content 6 to 8 percent. The clay and water furnish the bond for green sand. It is fine, soft, light, and porous. Being damp when squeezed in the hand, it retains the shape, the impression given to it under pressure. Moulds prepared in this sand are known as green sand moulds.
DRY SAND- Green sand that has been dried or baked after the mould is made is called dry sand. They are suitable for larger castings. Moulds prepared in this sand are known as dry sand.
LOAM SAND- Loam Sand is high in clay, as much as 50 percent or so, and dries hard. This is particularly employed for laom moulding usually for large castings.
FACING SAND- Facing sand forms the face of the mould. It is used directly next to the surface of the pattern and it comes into contact with the molten metal when the mould is poured. Consequently, it is subjected to the the severest conditions and therefore, must possess, high strength and ls with refractoriness. It is made of silica sand and clay, without the addition of used sand. Different forms of carbon are uscd to prevent the metal from burning into the sand. They are sometimes mixed with 6 to 15 times as much fine moulding sand to make facings.
BACKING SAND- Backing sand or floor sand or floor sand is used to back up the facing sand and to fill the whole volume of the flask. Old, repeatedly used moulding sand is mainly employed for this purpose.
The backing sand is sometimes called black sand because of the fact that old, repeatedly used moulding sand is black in colour due to the addition of coal dust and burning on coming in contact with molten metal.
SYSTEM SAND-In mechanical preparation and handling unit, no facing sand is used. The used sand is cleaned and reactivated by the addition binder in of water binders and special additives. This is known as system sand, In etimes mechanical foundries, where machine moulding is employed so called system sand is used to fill the whole flask. Since the whole mould is made of this system sand therefore, strength, permeability and refractoriness of this sand must be higher than those of backing sand.
PARTING SAND-Parting sand is used to prevent the green sand from sticking to the pattern and also to allow the sand on the parting surface of the cope and drag to separate without clinging. This is clean clay-free silica sand which serves the same purpose as parting dust
CORE SAND- Sand used for making cores is called core sand sometimes called oil sand. This is silica oil sand. This is silica sand mixed with core oil which is composed of linseed oil, resin, light mineral oil and other binding materials. Pitch or flours and water may be used in larger cores for the sake of economy.
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| Types of SAND in civil Engineering |
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