(1) According to the position of the choke section
A closed gating system
The closed gating system refers to the gradual reduction of the cross-sectional area from the bottom hole of the sprue cup to the inner sprue. The inner sprue is a flow blocking section, that is, ∑ f ＜∑ f ＜ f ＜ f ＜ f ＜ f ＜ f ＜ straight < f cup hole. Closed gating system is mainly suitable for small and medium-sized iron castings.
B open gating system
The open gating system means that the cross-sectional area from the bottom hole of the sprue cup to the inner sprue is gradually increasing, and the bottom hole of the sprue cup is the flow blocking section, that is, ∑ f internal > Σ f horizontal > F straight > F cup hole. The open gating system is mainly suitable for non-ferrous metal castings,castings and steel castings that are easy to oxidize.
C semi closed gating system
The sprue of the semi closed gating system is the flow blocking section, i.e., σ f is in the horizontal direction ≥ f is in the vertical direction ≥ σ F. Semi closed gating system is suitable for all kinds of iron castings, especially for nodular iron castings and surface dry mold.
D closed open gating system
The choke section of closed open gating system is located at the lower end of the sprue, i.e. f cup > F straight < Σ f cross > Σ F. The closed open gating system is generally used for small iron castings and aluminum alloy casting.
(2) According to the position of the internal sprue
A top pouring type (the inner sprue is located at the top of the casting)
Top injection type is suitable for thin-walled castings with simple structure and small height, with good feeding effect.
B bottom pouring type (the sprue is located at the bottom of the casting)
The bottom injection type is suitable for castings with small height and complex structure, poor feeding effect, good exhaust and slag retention.
C intermediate injection type (the sprue is located in the middle of the casting)
Intermediate injection is the most common pouring method.
D stepped type (the internal sprue is introduced in multiple layers)
Step type is suitable for castings with high height, especially for those with large shrinkage of liquid body.