Moulding Sands: Most sand casting operations use Silica sand (SiO 2 ). Usually sand used to manufacture a mould for the casting process is held together by a mixture of water and clay. A typical mixture by volume could be 89% sand, 4% water, 7% clay. Control of all aspects of the properties of sand is crucial when manufacturing parts by sand casting. Characteristics of Moulding Sand: Important characteristics are: 1. These sands are refractory in nature and can withstand temperature of the metal being poured, without fusing. 2. The moulding sands do not chemically react or combine with molten metal and can therefore be used repeatedly. 3. The sands have a high degree of permeability and thus allow the gases formed during pouring to escape. 4. The strength, permeability and hardness of the sand mix can be varied by changing the structure or ingredients of sand. Properties of moulding sands: The important properties are: 1. Strength 2. Permeability 3. Grain Size and Shape 4. Thermal stability 5. Refractoriness 6. Flow ability 7. Sand Texture 8. Collapsibility 9. Adhesiveness 10. Reusability 11. Easy of preparation and control 12. Conductivity
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