한국주조공학회

Green compressive strength, permeability, deformation, flowability, compactability and green hardness values at room temperature are dependable on the grain distribution and grain shape. The results obtained under constant moisture (4% for sand) and bentonite (8% for sand) were as follows; 1. With decreasing grain size, surface area of sand grain was increased. 2. With decreasing grain size, coefficient of angularity was increased. 3. As surface area increased from 8926.43cm^2 to 21211.16cm^2 , green compressive strength was increased from 210.93g/cm^2 to 449.98g/cm^2, hardness was increased from 76.7 to 82.3, but permeability was decreased from 411.7{frac{cc x ;cm}{atm x cm^2 x ;min.}} to 113.7{frac{cc x mm}{atm x cm^2 x min.}} 4. As surface area increased from 8926.43cm^2 to $21211.16cm^2, flowability was decreased from 82.3% to 80.8%, deformation was decreased from 67.1cm x 10^{-3} to $54.6cm x 10^{-3}, but compactability was increased from 44.8% to 54.3%. 5. Room temperature properties of molding sand were affected by variation of surface area.