Foundry gating — name the vertical channel: In sand casting, which gating element carries molten metal from the pouring basin down to the runner/gate system?

Introduction / Context:
Effective gating design ensures smooth, turbulence-minimised flow of molten metal into the mould cavity. The principal elements include the pouring basin, sprue, runner, gates, and risers. Identifying each element's function is a foundational foundry skill.

Given Data / Assumptions:

• Conventional green-sand mould with top pouring basin.
• Gravity-fed system; no pressurised gating.
• Standard terminology for gating components.

Concept / Approach:
The pouring basin receives metal from the ladle and dampens turbulence. The sprue is the vertical channel that conducts metal downward from the basin to the runner. The runner distributes metal horizontally to the gates, which finally feed the cavity. Risers are reservoirs that compensate for shrinkage during solidification. Cores form internal cavities; chills control local solidification by rapid heat extraction.

Step-by-Step Solution:
Trace flow path: Ladle → Pouring basin → Sprue (vertical) → Runner (horizontal) → Gate → Cavity.Identify vertical element: the sprue.Therefore, the component delivering metal from basin to the gate system is the sprue.

Verification / Alternative check:
Standard foundry diagrams consistently name the vertical down-run as the sprue and distinguish it from risers and runners.

Why Other Options Are Wrong:
Riser feeds the casting during solidification; it is not a delivery channel from the basin.

Core forms internal cavities; it is not a gating element for flow delivery.

Chill is a heat sink, not a channel.

Skim bob is a special feature for slag entrapment, not the main downsprue.

Common Pitfalls:
Confusing sprue with riser because both are vertical; ignoring the need for a tapered sprue to avoid aspiration; omitting a well at the sprue base, causing erosion.

Final Answer:
sprue