1997 Volume 69 Issue 2 Pages 113-118
This paper presents the results of the direct observation of the packing behavior of sand in the vacuum suction molding process for making sand cores and the investigation of the density distribution in produced cores. The packing mechanisms were studied based on these experimental results. The packing process can be divided into two stages : the first stage during which the sand flows rapidly and collides with cavity walls until the cavity is filled and the last stage when sand particles move slowly due to the air flow after the first stage. The final density depends on both the collision and D’Arcy effects in each stage. It was found that the following places tend to have lower density : corners where the sand is difficult to flow-in, places where the air flow is divided, places finally filled and places where a strong shear flow occurs.
