Reasonable wall thickness is proportional to the thickness of the casting

and inversely proportional to the difference between solidification temperature of liquid metal and preheating temperature of metal mould by transferring heating calculation.The larger the wall thickness of metal mould is

the larger its thermal capacity is.So the capability that decreases the temperature of molten metal through its own thermal capacity is the stronger.However

it is difficult for the metal mould to cool molten metal by using cooling media owing to the larger thermal resistance of the metal mould.When the wall thickness exceeds the reasonable wall thickness of the metal mould

effects of cooling methods on castings are slight

so the cooling effect is poor.The thermal resistance on circular direction for metal mould is low for the larger thickness of the metal mould

and effect of the mean temperature distribution of the metal mould is strong.It is suitable for simultaneous solidification.The metal mould with thin wall is contrary to the above results.