Gating Channel Layout

We all know that Gating system is nothing but the basic design which is needed to construct a smooth and proper filling of the mold cavity of the casting without any discontinuity, voids or solid inclusions.

You might me wondering what the channel layout is. It means that the efficiency of the gating system also depend on the number of ingates and location of ingates. It symbolically means that "channel" is the "number" of ingates used and "layout" is the location of ingates.

Let us take an example of the horizontal gating system. This type of gating system is used most widely in flat casting, which are filled under gravity. This is normally used in sand casting of ferrous metals and gravity die-casting of non-ferrous metals.

The location of the ingates is governed by the following criteria's:

Side Ingates : The ingates at the sides increase the efficiency of the gating system by filling the stream of molten metals through them. It helps to reduce the fettling effort too.

Thick ingate sections : Using thick ingates helps to reduce the breakage of the ingates during fettling process, since it allows the flow of molten metal with minimal cooling.

Ingate Path : Sand casting is accompanied with molten metal, which flows moderately with minimum disturbance and directional change. They should not be placed in a position opposite to the core.

Ingate position : If the free fall of the molten metal at the cavity is low, than the ingate should be placed in that position, because it reduces the oxidation and thus the erosion of the metal.

The sprue collects the molten metal from the pouring basin to the plane of the runner and ingates. So, even the location of the sprue plays a vital role in the gating system. So let us see the factors, which govern the sprue location.

Distance of flow : In order to reduce the heat loss and to have maximum yield, the sprue should be placed in a location where the total flow distance within the gating channel is minimum.

Concentration of Heat : In castings the sprue must be away from hot spots, since hot metal flows through the sprue.

Sprue Location : Sprue must be located in such a way that it reduces the size of the bounding box, which encloses the total cast, including the gating channels.

Runner Layout : It connects the ingate with sprue and it is governed by its shortest path.