Evaluation of the tendendy twoards buckles of green molding sand with simultaneous qualitative recording and comparison of the tendency towards defects of molding materials with different bentonites. A schematic buckle test illustration is shown in Fig. 1a.
There are two thin gates and an overflow in the drag box, two sprue cups in the cope box and another thicker gate. There are racks above the cope box model which interrupt the mold surface so that scaling is not impeded. Therefore, there a favorable casting conditions at the buckle test. The gates are narrow, the casting velocity is low and the metal pressure height is low, too, which make the development of rat tails possible.
For extending heat radiation on the mold cavity, the casting process is interrupted for a short time after half the mold was filled. For this reason, there is scaling due to the rising casting material. For concluding the test, the mold is fillled through the sprue cup on the other side and sand defects can dispay in the solidifying casting material. Fig. 1b and c illustrate low and middle tendencies towards defects after the buckle pilot casting.
Scabbing time diagram