12.Type of castings

As it is pointed out by many researchers the gap size mainly depends on the gas that is formed in the interface. The rate of solidification of castings made in a sand mold is generally controlled by the rate at which heat can be absorbed by the mold. In fact, compared to many other casting processes, the sand mold acts as an excellent insulator, keeping the casting warm. However, of course, ceramic investment and plaster molds are even more insulating, avoiding premature cooling of the metal, and aiding fluidity to give the excellent ability to fill thin sections for which these casting processes are renowned. It is regrettable that the extremely slow cooling can contribute to rather poorer mechanical properties.

Extensive literature reviews have been made, in order to determine the interfacial heat transfer behavior during the solidification of casting at the metal-mold interfaces, since the 1970's. The boundary conditions as a surface heat flux and mold surface temperature established at the metal mold interface were used to determine the precise interfacial heat transfer coefficient value by using many mathematical methods described in the literature. The most common approaches can be distinguished here as follows for the determination of IHTC at the metal-mold interface including surface heat flux and mold surface temperature:


The following section explains the detailed procedure of these methods listed above.
