Foundry Sand Testing

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Title: Foundry Sand Testing Objectives: (a) To get the grain fineness number and clay content of foundry sand (b) To determine the green compressive strength and hardness of the sand (c) To learn about the permeability of foundry sand Introduction: Sand casting is the traditional method of casting metals. Most sand-casting operations use silica sand (SiO2) as the mold material because of its high temperature characteristics and high melting point. Several factors are important in the selection of sand for molds and certain tradeoffs with respect to properties are involved. Sand having fine, round grains can be packed closely and thus, forma a smooth mold surface. Although fine-grained sand enhances mold strength, the fine grains also lower mold permeability. Good permeability of molds and cores allow gases and steam evolved during the casting to escape easily. The mold also should have good collapsibility to allow the casting to shrink while cooling and to avoid defects in the casting, such as hot tearing and cracking. Therefore, the sand that is going to be used must be undergoing several tests to fulfill the requirements. The tests are the grain fineness number, clay content test, green compressive strength, hardness test, permeability. Procedures: 1. The Grain Fineness Number Apparatus: (a) Silica sand (b) Mass balance (c) Bench Mounted Sieve Shaker (d) Brush Procedure: 1) 100 g silica sand was weighed. 2) The sieves were all cleaned and the sieve was placed according to their sieve number from higher to lower. 3) The sample was poured on the top sieve and the sieve was closed tightly. 4) The sieve shaker was switched on and it was operated for 15 minutes. 5) The weight of the retain sand on each of the sieve was measured separately. 6) The GFN of the sample was calculated by using the formula.

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