What is Gate in Casting? (3 Types of Gates You Should Know!)

Gate in Casting

What is Gate in Casting?
In Casting, the gate is a small channel or passage which connects the runner with a mold cavity and the molten metal flows through this passage to fill up the mold cavity.

Types of Gates in Casting

There are basically 3 types of gates in casting which are classified on the basis of their positions. They are mentioned below.

  1. Parting line gate
  2. Top gate
  3. Bottom gate

#1) Parting line gate

types of gates in casting (Parting line gate)

Parting line gate is one of the simplest types of gate in which molten metal enters the mold cavity at the parting line.

Parting line gate can be cut with the help of hand also when the cope and drag portion of the mold are opened.

Or it can also be made by attaching the gate with the casting pattern.

#2) Top gate

top gate in casting

Top gate is a type of gate in which the molten metal directly flows into the mold from the top side (see above image)

Because of this, the hottest metal stays at the top of the mold.

This results in the directional solidification of the metal from bottom to top.

In this type of gate, the gate itself acts as a riser.

These type of gates has many advantages like;

  • It is simple to make the gate in the mould.
  • Consumption of additional metal is low.
  • The temperature gradient is generated in the liquid metal which enhances the directional solidification from bottom to top.

The main disadvantage of top gate is that the mold gets eroded due to direct falling of the molten metal in the mold.

Thus the strength of the mold should be high enough to resist the flow of molten metal.

#3) Bottom gate

bottom gate in casting

In bottom gate, the molten metal is poured in the sprue and it flows downward and enters the mold cavity from the bottom of the mould cavity.

By using this type of gate in casting, the erosion of the mold and core can be minimized.

By using the bottom gate, the turbulence of metal can also be reduced.

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