Question

In metal casting, which one of the following gating ratios (sprue-runner-gate area ratio) represents a non-pressurized gating system?

• A. 1 : 2 : 3
• B. 3 : 2 : 1
• C. 4 : 3 : 1
• D. 5 : 4 : 1

Hint:

In non-pressurized gating systems, a 1:2:3 ratio of sprue-runner-gate area is typically used, where gravity plays the primary role in the flow of molten metal into the mold.

Answer 1

The Correct Option is A

In metal casting, the gating system is designed to direct molten metal into the mold. The gating ratio, specifically the sprue-runner-gate area ratio, plays a key role in controlling the flow and pressure of molten metal. A non-pressurized gating system relies on gravity rather than pressure to push the molten metal through the gating system.
Step 1: Understanding the gating ratio
- The sprue is the main channel through which the molten metal enters the mold.
- The runner is a horizontal channel that directs the metal to the gate.
- The gate is the final entry point through which the molten metal enters the mold cavity.
In a non-pressurized system, the gating ratio must be set in such a way that the metal flows naturally without the need for additional pressure. Typically, for a non-pressurized system, the gating ratio follows the pattern of 1 : 2 : 3 for sprue:runner:gate area
Step 2: Analyze the options
- Option (A): Correct — A gating ratio of 1 : 2 : 3 represents a non-pressurized system, where the flow of molten metal relies on gravity.
- Option (B): Incorrect — This gating ratio is more suited to a pressurized system.
- Option (C): Incorrect — This gating ratio is often used for high-pressure systems.
- Option (D): Incorrect — This is also not suitable for non-pressurized systems.
Step 3: Conclusion The correct answer is Option A, which corresponds to a non-pressurized gating system in metal casting.