Abstract
The reason why the molten metal does not penetrate into the openings of sand grains is because of its great surface tension.
Thus, the author thinks that the penetration or blow as the casting defects seems to be related to the surface tension of molten metal, so that the critical limit of penetration or blow and the relation between penetration and washes of sand molds were investigated by using mercury, which surface tension and density are similar to those of molten metal, in this report.
From the results of the experiment, (1) the pressure which causes the penetration is inversely proportional to the size of the mold opening (2) the penetrating pressure increases when the back pressure exists (3) when the back pressure beyonds its critical range, the blow occurs regardless of the state of mold surface.
