The so-called pouring system refers to the general name of the channel that guides the molten metal into the mold cavity. Its main components include sprue cup, direct sprue, cross sprue and internal sprue. The sprue cup is used to hold the liquid metal and prevent the liquid metal from splashing and overflowing during pouring. The main function of the direct sprue is to guide the liquid metal in the sprue cup into the transverse sprue, and to establish enough pressure head, so that the liquid metal can overcome the flow resistance under the action of gravity, so that the liquid metal can fill the entire cavity in a certain period of time, which can prevent the liquid metal from splashing and overflowing in the casting The main function of the runner is to control the filling speed and direction and adjust the heat difference of each part of the casting.
According to the area ratio of each component, the gating system can be divided into open gating system and closed gating system. The inner sprue of the closed pouring system shall be located at the lower part of the cross sprue and have the same bottom plane as the cross sprue (as shown in figure a); the inner sprue of the open pouring system shall be located at the top of the cross sprue. In order to prevent the scum from entering the inner sprue before the cross sprue is full, the top surface of the cross sprue and the top surface of the inner sprue shall not be in the same plane (as shown in Figure b). The gating system can be divided into top gating system, bottom gating system, middle gating system and step gating system according to the position of the inner runner on the casting.