Characteristics of foundry moulding sands

Abstract

The purpose of this report is to demonstrate how the properties might be controlled by means of simple testing to reveal the full properties of foundry sand. Moulding sands possess qualities which retain their forms when molten is poured into them. Their requisites are chemical composition to resist fusion from the heat of the molten; to permit the free escape of gases from moulds without scabbing or otherwise injuring the surface of the mould. The sand also should be capable of being retempered and used for successive moulds without addition of new sand to provide the necessary bond. Further the specifications for foundry moulding sands are that these should be easy to ram, give a good draw and withstand the application of the trowel. Foundrymen have methods of testing the physical qualities of moulding sands. For instance, a foundrymen will take a handful of tempered sands. For instance, a foundrymen will take a handful of tempered sand, squeeze it in his hand to form an elongated mass and suspends it by one weight, it is not considered a strong sand .If, however, it hangs together, thus indicating strength, there may be present an excessive amount of clay. Amount of clay is judged from the stickiness of the sand.