MOULDING MATERIALS
Different types of moulding materials are
-moulding sand
-system sand (backing sand )
-rebonded sand
-facing sand
-parting sand
-core sand
Choice of moulding materials depends on processing properties.
Properties_-
1) Refractoriness- Ability to withstand high temperature of molten metal so that it does not cause fusion
Refractory materials - silica, zirconia, alumina
2) Green strength- Moulding sand containing moisture is known as green sand. The strength of the green sand is known as green strength.
3) Dry strength- When moisture is completely expelled from the moulding sand, it is known as dry sand and the strength of the sand is the dry strength.
4) Hot strength- After moisture elimination, the sand is exposed to higher temperature of molten material. Strength of sand to hold the shape of mould cavity at this higher temperature is known as hot strength.
5) Permeability – Moulding sand is porous, so it escapes gases through it. This gas evolution capability of moulding sand is known as permeability.
Other properties include collapsibility, reusable, good thermal conductivity etc.
Different types of moulding materials are
-moulding sand
-system sand (backing sand )
-rebonded sand
-facing sand
-parting sand
-core sand
Choice of moulding materials depends on processing properties.
Properties_-
1) Refractoriness- Ability to withstand high temperature of molten metal so that it does not cause fusion
Refractory materials - silica, zirconia, alumina
2) Green strength- Moulding sand containing moisture is known as green sand. The strength of the green sand is known as green strength.
3) Dry strength- When moisture is completely expelled from the moulding sand, it is known as dry sand and the strength of the sand is the dry strength.
4) Hot strength- After moisture elimination, the sand is exposed to higher temperature of molten material. Strength of sand to hold the shape of mould cavity at this higher temperature is known as hot strength.
5) Permeability – Moulding sand is porous, so it escapes gases through it. This gas evolution capability of moulding sand is known as permeability.
Other properties include collapsibility, reusable, good thermal conductivity etc.
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