2006 Volume 78 Issue 2 Pages 53-58
In the planning of defect prevention for the evaporative pattern casting of cast iron, it is necessary to understand the behavior of expandable pattern during thermal decomposition as well as the melt filling behavior. In this study therefore, the effects of the permeability of the coating of the expandable pattern on its surface shape during thermal decomposition, the surface shape of the molten cast iron and the gas gap thickness were investigated, and the following results were obtained.
Convex height in the surface shape of the expandable pattern during thermal decomposition of expandable pattern and that of molten cast iron increases when the coating permeability is low. The shape of the pattern surface does not always correspond exactly with the shape of the melt surface, and in this case the shape of thermal decomposition gas gap becomes the shape of the convex lens. Further, a low coating permeabilityleads to a larger gas gap thickness. The mean decomposition gas pressure, on the other hand, was found to show a level slightly lower than the melt head, and effect of the permeability of the coating is not significant.
