Question

Which casting process is best suited for producing hollow, symmetrical parts with good surface finish and precise wall thickness, such as pipes and cylinder liners?

• A. Die Casting
• B. Centrifugal Casting
• C. Investment Casting
• D. Sand Casting

Hint:

Key industrial products made by Centrifugal Casting:
- Large cast pipes.
- Gun barrels.
- Engine cylinder liners.
- Symmetrical rings and pulleys.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question asks for the casting method best designed to fabricate hollow, symmetrical, cylindrical parts like metal pipes and engine cylinder liners without utilizing cores.

Step 2: Key Formula or Approach:
The process uses centrifugal forces to distribute molten metal uniformly against the inner walls of a rapidly rotating mold cavity.
The centrifugal acceleration \( a_c \) generated is:
\[ a_c = \omega^2 r \]
where:
\( \omega \) is the angular velocity of the mold.
\( r \) is the mold radius.

Step 3: Detailed Explanation:

• Centrifugal Casting Principle:
- Molten metal is poured into a rotating mold (usually spinning on a horizontal or vertical axis).
- The centrifugal force drives the heavy liquid metal outward against the inner walls, where it solidifies.
- No central sand or metal core is needed to form the hollow interior. This saves significant manufacturing time and cost.

• Product Quality:
- The centrifugal force naturally separates lighter impurities, slag, and trapped gases from the denser liquid metal.
- These impurities gather at the inner surface of the hollow section and can be easily machined off after solidification.
- This results in a casting of exceptionally high density, uniform wall thickness, and fine grain structure.

• Comparison: Sand casting and die casting require complex core inserts to produce hollow interiors, which is far less efficient for simple symmetrical cylinders.


Step 4: Final Answer:
Centrifugal casting is the primary industrial method for producing hollow, symmetrical parts like pipes and cylinder liners.
Thus, the correct option is (B).