A core is a pre-determined shaped mass of dry sand, which is made separately from mould. It is positioned in a mould to obtain a shape in the casting which can’t be readily obtained by the mould properly. Core box pattern equipment, baking equipment and handling facilities are required for making of cores.Core can be eliminated when of small size particularly, if the hole is to be machined. Cores should be of sufficient thickness and free of fragile or overhanging projections, which might be easily broken during the necessary handling and transportation involved in production.