Abstract
The quality of bonding materials mixed with the molding sand has a great influence upon the properties of the sand. Great many conditions are required to clays used for molding sand, but among them, the bonding power should be the greatest necessity. The authors have made a study on this subject in order to judge the quality of clays for molding sand, and have made an investigation on the simple judgment of clay for molding sand. The results obtained are as follows : i) The bonding power of clay-combined-sand usually increases in proportion to the increasing bonding power of clay. ii) The bonding power of clay minerals and clay-combined-sands increases in accordance with the increasing amount of clay substance in clay and colloidal materials contained in clay minerals. Therefore, the quality of clay for molding sand will be determined by the contents of clay and colloidal substances in clay minerals. iii) The contents of clay and colloidal substances in clay minerals may be measured quickly and simply by utilizing centrifugal force.
