Green sand moulding:

The sand utilized for green sand moulding ought to fulfil a number of requirements:

(a) It ought to pack tightly around the pattern, that means that it ought to have flow ability.

 (b) It must be capable of being deformed slightly without cracking, so that the pattern may be withdrawn. In other terms, it should exhibit plastic deformation.

 (c) It should have adequate strength to strip from the pattern and support its own weight without deforming, and to withstand the pressure of molten metal while the mould is cast. Therefore it must have green strength.

 (d) It ought to be permeable, so that gases and steam may escape from the mould throughout casting.

 (e) It ought to have dry strength, to avoid erosion of the mould surface by liquid metal throughout pouring as the surface of the mould cavity dries out.

 (f) It ought to have refractoriness, to withstand the high temperature included in pouring devoid of melting or fusing to the casting.

 (g) Along the exception of refractoriness, all requirements are based on the amount of active clay present and on the water content of the mixture.

For the above said qualities, moulding sand ought to have some properties. It is not necessary for the sand to contain all these properties at the similar time rather it based on the application for which sand is going to be utilized. According to the application these properties may be acquired at the similar time economics may be worked out.