A model of mould used in sand casting is shown in Figure 20.2. Moulding material that is packed around the pattern to provide the mould cavity is green sand. The various parts of mould can be defined as follows:
Figure 20.2 A Model of Mould Used in Sand Casting
Flask: It is a rigid box which opens at top and bottom that holds the complete mould. Flask may be divided into three parts—the upper, middle, and lower; these three parts are known as cope, cheek, and drag, respectively.
Core: A sand or metal shape that is inserted into the mould to create internal hole or recess.
Mould Cavity: It is a cavity of casting shape in the mould connected to runner and riser. It is used to pour the molten metal in which metal solidifies and gets the shape of cavity.
Riser: An additional opening in the mould that provides additional metal to compensate for shrinkage and also helps to remove gas or vapour formed during pouring the molten metal into the cavity.
Gating System: It is a network of channels that deliver the molten metal to the mould cavity.
Pouring Cup/Basin: It is located at the top surface of the mould and connected to upper part of downsprue. It prevents the splitting of molten metal.
Downsprue: It is vertical portion of the gating system. It facilitates the streamline flow of molten metal.
Runners: It is horizontal channels which connects the downsprue and gates.
Gate: It controls the amount of flow of molten metal at the entrance of cavity.
Parting Line: It is dividing line of cope and drag.
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