Gating System in Casting — What Is the Primary Function of a Gate? Within a standard sprue–runner–gate system, what is the specific purpose of the gate relative to the mould cavity?

Introduction / Context:
Gating systems regulate the flow of molten metal from the pouring basin through the sprue and runner to the mould cavity. Each element has a distinct role, and correct terminology avoids design mistakes that lead to defects.

Given Data / Assumptions:

• Sprue connects pouring basin to runner.
• Runner distributes metal horizontally.
• Gate is the final controlled opening into the cavity.

Concept / Approach:
The gate controls the final entry conditions (velocity, turbulence, and direction) as metal enters the mould cavity. Its shape and location strongly affect defect rates such as erosion, inclusions, and cold shuts. Reservoir and feeding functions are handled by risers, not gates, while vents discharge gases and air.

Step-by-Step Solution:
Map each component: sprue → runner → gate → cavity.Recognize that the gate is the last flow restriction before the cavity.Therefore, its primary function is to deliver molten metal into the cavity under controlled conditions.

Verification / Alternative check:
Foundry handbooks define gates as the inlets to the casting, designed to minimize turbulence and defects.

Why Other Options Are Wrong:
Reservoir/feeding: functions of risers, not gates.Delivering from basin to gate: performed by the sprue and runner, not the gate itself.Vent function is handled by vents and cores, not gates.

Common Pitfalls:
Confusing feeders with gates, leading to poor feeding design.

Final Answer:
deliver molten metal into the mould cavity