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Why can engineering plastics compete with metals in machine and automotive parts?

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major industrial polymers Figure 1: The linear form of polyethylene, known as high-density polyethylene (HDPE).

Engineering plastics, also known as engineering resins, are specialty polymers specifically tailored to possess mechanical properties that allow them to compete with die-cast metals in demanding applications such as machine, automotive, and hardware parts.1

These materials are able to replace metals because they offer a combination of high strength, stiffness, and dimensional stability. For example, polymers like polyetheretherketone (PEEK) and polyphenylene sulfide (PPS) exhibit high tensile strength and flexural modulus, particularly when reinforced with glass fibers, making them suitable for structural machine and automotive components.12

Unlike commodity plastics, which are produced in high volumes for disposable goods, engineering plastics are specialty resins produced at lower volumes to meet specific performance requirements. Their ability to withstand stress and maintain their shape under load—often characterized by properties like tensile strength and resistance to creep—enables them to function effectively in environments where traditional metal parts were once the standard.12