Venting and Setting of Cores

Why venting of core is necessary? Also define the setting of core.

Venting and Setting of Cores

When molten metal comes in contact with a core placed in the mold, core gives off gases which should be allowed to escape out of the mold otherwise they may create serious defects in the casting. To meet this requirement provisions like holes and channels are made in a core.

A small round core may be vented by running a vent rod through the core centre when it is under preparation. In a core made in two halves, channels may be cut for venting. Some intricate cores are vented with the help of vent wax embedded along the lines in the core sand where the escaping gases are to follow. After the core has been baked way melts and disappears leaving the vent channels desired.

Projections in the form of core print arc provided to help in setting the core in a mold. Sometimes cores are supported on metallic chaplets inserted in the mold sand. When liquid metal comes in contact with these chaplets, they melt and become a part of the casting. Chaplets must -be- clean, dry and carefully selected as required. Few cores have anchor rods or wires to support them in a mold.