Which of the following is NOT a characteristic of plastics that makes them good for manufacturing parts?

• A. Conductive
• B. Lightweight
• C. Moldable
• D. Resistant to corrosion

Answer: (A)

Plastics are chosen for parts mainly because they are lightweight, easy to shape, and resistant to corrosion. Being lightweight helps reduce weight and energy use in transport and operation. Their moldability comes from polymer chemistries that soften when heated and harden when cooled, enabling complex shapes and precise tolerances through methods like injection molding, extrusion, or additive manufacturing. Corrosion resistance stems from plastics’ nonmetallic nature, which keeps them from rusting or corroding in many environments, extending part life.

Conductivity is not a typical property of plastics. Most plastics are electrical insulators, which is advantageous for isolating circuits and preventing unwanted current flow. If conductivity is required, designers would add fillers or choose special formulations, but that changes the material’s other properties and isn’t the inherent reason plastics are valued for parts.