If you are an engineer in the aerospace industry, you are looking to work with materials that can withstand extreme conditions while maintaining precision, safety, and reliability. You are likely aware that high-performance plastics are increasingly replacing metals in various applications due to their strength-to-weight ratio, resistance to harsh environments, and ability to meet stringent regulatory standards. However, whether using injection molded or machined components, selecting the appropriate plastic involves a thorough understanding of the component’s function, the environmental conditions it will face, and the capabilities of the manufacturing process. If you are not as familiar with these materials as metals, we will walk you through how to choose the optimal polymer for your specific application. Of course, we are always available for a consultation.

Key Characteristics for Aerospace Applications

Components used in aerospace must meet stringent performance requirements tailored to their intended function. Reliability is non-negotiable for mission-critical aerospace components. As a result, various high-performance plastics are used throughout an aircraft, each selected for its specific advantages. Engineers must thoroughly understand the physical and environmental pressures a component will encounter, whether these stresses are continual or intermittent, to ensure optimal material selection.

Some of the rigorous performance requirements for aerospace components include the following:

  • High Strength-to-Weight Ratio – Reducing aircraft weight enhances fuel efficiency and overall performance. Many advanced polymers offer comparable strength to metals at a fraction of the weight.
  • Thermal Stability – Materials must withstand extreme temperature fluctuations, from subzero conditions at high altitudes to high heat in engine compartments.
  • Fire, Smoke, and Toxicity Compliance – Federal aviation regulation 14 CFR 25.853 dictates fire safety requirements for compartment interiors, and 14 CFR 25.855 has requirements for cargo and baggage compartments.
  • Chemical and Corrosion Resistance – Exposure to fuels, hydraulic fluids, de-icing chemicals, and UV radiation necessitates materials with strong chemical resistance.
  • Dimensional Stability and Machinability – Parts require precise tolerances and stability under operational stress, making certain plastics ideal for both machining and injection molding.
  • Electrical Insulation – Many polymers provide inherent non-conductive properties, essential for electronic enclosures and wiring applications.

Common High-Performance Plastics Used in Aerospace Applications

The best material for an application depends on the conditions it encounters in use and the manufacturing process. Some materials perform better with injection molding, while others are better suited for CNC machining.

Several high-performance plastics are commonly used in aerospace applications, each chosen for their unique properties that meet specific requirements.

Polyether Ether Ketone (PEEK) is favored for its high strength-to-weight ratio, heat and chemical resistance, and wear resistance, making it suitable for fuel system components, engine parts, and flight control mechanisms. It can be both injection molded for high-volume production and machined for precision components.

Polyetherimide (PEI), also known as Ultem®, offers exceptional heat resistance, good electrical insulation, and high strength, making it ideal for interior components, electrical enclosures, and structural panels, primarily through injection molding.

Polyphenylene Sulfide (PPS) is known for its high-temperature stability, chemical resistance, and flame resistance, and is used in ducting systems, hydraulic components, and insulation. PPS is best suited for injection molding, ideal for complex parts requiring tight tolerances and chemical resistance.

Polyimide (PI) provides extreme temperature resistance, high mechanical strength, and low outgassing, making it suitable for thermal insulation, bushings, bearings, and electrical insulation. PI is a non-melting polymer, so it is ideal for machined components.

Polyvinylidene Fluoride (PVDF) is chosen for its chemical resistance, good mechanical properties, and flame retardancy, and is used in fluid-handling systems, seals, gaskets, and cable insulation. PVDF can be both injection molded or machined for custom parts requiring tight tolerances.

Polyamide-Imide (PAI), also known as Torlon®, is valued for its high strength at elevated temperatures and exceptional wear resistance, making it suitable for bushings, bearings, fasteners, and high-load structural components. Due to its rigidity, PAI is typically machined; however, Solvay, the producer of Torlon, has an approved molder qualification process, which allows select manufacturers to injection mold it.

Polybenzimidazole (PBI) offers the highest heat resistance of any thermoplastic and excellent wear properties, making it ideal for engine components, insulation, and high-temperature seals. PBI is best machined for high-temperature, high-performance precision parts.

How Ensinger Helps Engineers Select the Right Material

Choosing the right polymer requires understanding each application’s operational demands and compliance requirements. We specialize in engineering and high-performance plastics, offering material selection and processing methods expertise. Whether replacing metal components to achieve weight reduction or meeting extreme temperature requirements, our plastics experts work with aerospace engineers to develop the best solutions.

If you need guidance in selecting an aerospace-grade plastic that meets both performance and regulatory standards, contact us today to explore your options.