Risers-

Risers are reservoirs of molten metal to feed the casting during solidification to compensate for solidification shrinkage. Shrinkage in casting occurs when the temperature of the liquid metal drops from pouring to freezing temperature, metal changes from liquid to solid state and the solid-phase temperature drops from freezing to room temperature. The function of the riser is to compensate for compensates for stage.

Gating System-

Gating system serves to deliver molten metal to all corners of mould cavity and is designed to minimize turbulence and erosion. The molten metal is poured into the pouring basin and it moves through the sprue to enter the runner. The sprue is usually tapered down to prevent aspiration of gasses through the sprue. The sprue well serves to dissipate the kinetic energy of falling molten metal before it enters the runner through the choke. The choke is provided to avaid the creation of vacuum, since the liquid metal tends to contract when there is a sudden change in the flow direction.

Gating System-

Gating system serves to deliver molten metal to all corners of mould cavity and is designed to minimize turbulence and erosion. The molten metal is poured into the pouring basin and it moves through the sprue to enter the runner. The sprue is usually tapered down to prevent aspiration of gasses through the sprue. The sprue well serves to dissipate the kinetic energy of falling molten metal before it enters the runner through the choke. The choke is provided to avaid the creation of vacuum, since the liquid metal tends to contract when there is a sudden change in the flow direction.

Melting and Pouring-

Several types of furnaces are used for obtaining molten metal. Cupola is extensively used for melting cast iron primarily because of lower initial cost as well as melting cost. Induction furnaces and side-blow converter are used for melting other foundry alloys.
The most common way of pouring the molten metal into the mould cavity is through the use of ladles. Molten metals react with oxygen to form metal oxides and these must be separated out from the molten metal entering the mould cavity. Since slag can be easily separated from molten cast iron, top pouring ladles perform satisfactorily. For steels, bottom pouring ladles are generally used for effective slag separation.