Which process uses a mold to shape thermoplastics?

• A. Vacuum forming
• B. Injection molding
• C. Die casting
• D. Extrusion

Answer: (A)

Using a mold to shape a thermoplastic is about forming a heated plastic sheet over a cavity so the sheet takes the mold’s contour. Vacuum forming does exactly this: you heat a plastic sheet until it’s pliable, place it over a mold, and use suction to pull the sheet into and around the mold, producing a shallow, hollow part with the mold’s shape. This method is efficient for large, simple shapes like trays, enclosures, or panels because it’s well-suited to forming thin-walled objects from thermoplastics.

Injection molding also uses a mold, but it works by injecting molten plastic into a cavity, which is ideal for high-volume, detailed parts. Die casting involves shaping metal, not plastic, so it’s not about thermoplastics. Extrusion shapes material by forcing it through a die to create continuous profiles, rather than forming a finished 3D part from a mold.