<Dl> <Dd> t = B (V A) n (\ displaystyle t = B \ left ((\ frac (V) (A)) \ right) ^ (n)) </Dd> </Dl> <Dd> t = B (V A) n (\ displaystyle t = B \ left ((\ frac (V) (A)) \ right) ^ (n)) </Dd> <P> Where t is the solidification time, V is the volume of the casting, A is the surface area of the casting that contacts the mold, n is a constant, and B is the mold constant . It is most useful in determining if a riser will solidify before the casting, because if the riser does solidify first then it is worthless . </P> <P> The gating system serves many purposes, the most important being conveying the liquid material to the mold, but also controlling shrinkage, the speed of the liquid, turbulence, and trapping dross . The gates are usually attached to the thickest part of the casting to assist in controlling shrinkage . In especially large castings multiple gates or runners may be required to introduce metal to more than one point in the mold cavity . The speed of the material is important because if the material is traveling too slowly it can cool before completely filling, leading to misruns and cold shuts . If the material is moving too fast then the liquid material can erode the mold and contaminate the final casting . The shape and length of the gating system can also control how quickly the material cools; short round or square channels minimize heat loss . </P>

Holding temperature and pressure constant what is the most important feature