Abstract: A group of sprue-runner control gating systems with geometric similarity are also dynamicl similarity, inproved in theory. The Eu= F (Re) curve and Re of these kinds of gating systems are the same. The conclusions are proved by using of water model test and of the practical casting of molten iron from both theory and practice to be testified. The conclusion is obtained: Re≥Rle is the only condition for entering the second self-similuting area for the both sprue-runner control gating system model and the prototype.

Key words: Flowage, Gating system, Model, Number, Prototype, Similarty