A continuous process where material is forced through a shaped die to create a constant cross‑section?

• A. Casting
• B. Injection Moulding
• C. Forging
• D. Extrusion

Answer: (D)

The process described is extrusion. In extrusion, material is forced through a shaped opening (a die) so it flows and emerges as a long piece with the cross-section defined by the die. This creates a continuous length with a constant profile, which is ideal for producing things like aluminum channels, plastic tubes, or other long shapes. The material can be pushed hot or cold, depending on the material, to suit the die design and application.

Casting would involve pouring molten material into a mold to form a shape, which is not a continuous process along a length and the cross-section is set by the mold. Injection moulding forces molten material into a mold cavity to make discrete parts rather than long continuous shapes. Forging shapes metal by compressive forces, typically in dies, but it doesn’t push material through a die to create a uniform cross-section along a continuous length.