Abstract
In order to separate the pattern from the green sand mold successfully, chromium-plated patterns are usually used in the foundry. However, it was found sometimes that a good molding could not be obtained because of the strong adhesion at the all contact surfaces between the pattern and the mold. This work probes into the generation mechanism of this adhesion, togather with the influence of the adhesion on the stripping force. The pattern-mold adhesion occured as the adhesive property of the binder grew in the green sand when the temperature of the pattern was lower than that of the green sand. This is due to condensation of water vapor in the green sand in the vicinity of the contact surfaces of the pattern, which wets the binder suitably, and leads to the adhesion of the binder on the surface of the pattern. On the other hand, the adhesion between the pattern and the mold disappeared when the temperature of the pattern was higher than that of the green sand due to dry out of the binder in the green sand which contacted the surface of the pattern. Stripping force increases by the boundary friction force in addition to the adhesion between the pattern and the mold when the temperature of the pattern was lower than that of green sand. On the other hand, the stripping force was reduced due to the disappearance of the adhesion when the temperature of the mold was higher than that of the green sand. The boundary friction force seems to result from the spring-back of the green sand mold.
