Ramming pressure, sand

For any sand used, the higher the air pressure, or ramming pressure, used to form the sand shape the greater will be the bulk density of the resultant sand body. Fig. 3 shows the relationship between tensile strength and blown sand bulk density for two different sand systems. The lowest strength on each curve was obtained using 0.35 MPa, 50 psi, blow pressure. 

Conventional foundry practice can be followed to form and set the sand core or mold. The sand can be compacted by being rammed, squeezed or pressed into the core box either by hand or automatically, or can be blown into the core box with air under pressure. 

A Dietert CO2 gassing fixture set No. 655 supplied by the Harry W. Dietert Co. of Detroit, Mich, was used to harden the sand specimens by making CO2 gas flow through them at a controlled rate for an optimum period of time. The CO2 setting equipment consists of a pressure reducer and flow meter, and gassing fixtures for the standard 2 in. diameter precision specimen tube where the sand specimen is rammed. 

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