User manual

Appendix I
ZCast Design Guide - 38
11.1.4 Pouring Cup
The pouring cup, as the name implies, is
where the molten metal is poured into
the mold. The pouring cup can take
many different forms, each to optimize
the feeding of metal into the mold and
minimize the amount of turbulence
produced in the metal stream.
11.1.5 Sprue
The sprue connects the pouring cup to the gating system.
It is typically a conical shape tapering in as it extends
through the cope and into the drag. The sprue (with the
pouring cup at its top) should be the tallest component of
the mold. The height is what produces the pressure needed to fill the mold with metal. The sprue
should be at least 4 in (102 mm) higher than the casting.
The base of the sprue is often used as a choke to control the flow rate of metal into the mold.
The diameter of this point can be derived from the geometry of the casting and the subsequent
gating design.
11.1.6 Well
Just beyond the choke at the bottom of the sprue, the metal path opens up to the well. The well
is typically a cylindrical opening with a diameter about 2.5 times bigger then the choke. It directs
the metal to the runner system. The well often serves the dual purpose of housing a filter. Filters
are usually ceramic webs or open cell sponges used to help remove some of the dross (metal
oxides) and dirt from the molten metal.
11.1.7 Runners
Runners are the paths that feed metal around the mold to regions farthest from the pouring cup.
Runners are usually designed to minimize the turbulence of the metal as it travels through them.
Typically, they are rectangular in cross section, and again, like many other components of the
gating system, the runner dimensions can be determined from the cast part’s geometry. Runners
also serve as additional filters. They will often run out to a dead end beyond the last ingate. It is
in this dead end that dirt, debris and dross collect, while good, clean metal enters the mold.
Figure 18: Core prints – pockets where cores lock in
p
lace
(
dra
g
of manifold from Fi
g
ure 15
)
Core prints
(light areas)
Pouring Cup
Sprue
Well
Figure 19: Pouring cup, sprue and well.
The well is typically where the filter
would be placed