**3.1 Liquid shrinkage**

The superheated metal which is poured in the liquid state has more specific volume than the liquid metal in the cavity [2]. This liquid metal occupies the mold cavity and is in superheated state and comes in complete contact with the mold surface. Here the mode of heat transfer is purely conduction shown in **Figure 3**. On solidification there is a liquid contraction due to reduction in specific volume, the metal cools further and reaches to a liquidus temperature. This contraction of liquid metal separates cast and mold surface and imitates the air gap formation which is assigned as liquid shrinkage.
