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Manufacturing and Design Flexibility

One reason aluminum had been so frequently used for aerospace is that it was considered easy to manufacture into aircraft components. A misconception is that thermoplastics don't share that quality. Advances in thermoplastic manufacturing and processing have allowed for great flexibility in both manufacturing and design. One major thermoplastic and composite manufacturing misconception is that plastic parts cannot be easily machined. On the contrary, thermoplastic components have been machined into geometrically complex mission critical components over the past few decades.

Thermoplastics can be machined to extremely tight tolerances up to 0.002mm, which can be critical for aerospace applications. Processes such as rapid thermoforming, autoclave processing, tape and fiber placement techniques and press forming are also all possible with thermoplastic polymers and composites.

Many thermoplastics also have better fatigue properties than metals do, and they tolerate larger deflections without deforming. To prove this fact, just look at the wing flex on a Boeing 787 in flight as shown in the accompanying illustration.

Polymer and composite materials help reduce aircraft weight by being up to ten times lighter than metal.

PEEK is one thermoplastic that has fast become a popular replacement for metal in aerospace. It's a natural choice since PEEK's lightweight nature, mechanical strength, creep and fatigue resistance, and ease of processing all give it great versatility. PEEK's diversity of applications includes flight control, fuel systems, aircraft interiors, and engine and aerodynamic-related components.

Conclusion

There are numerous types of thermoplastics gaining ground in aerospace, many more than are named in this article. Yet it's important to remember that each thermoplastic, though sharing broad characteristics, has its own unique strengths that make it better suited for some applications over others. It's not unexpected that an aircraft engine has different needs than a RADEL aircraft galley bezel or a landing gear component.

When determining thermoplastic solutions, it's crucial to practice due diligence and partner with an experienced aerospace plastics manufacturer. They should be able to offer material consultancy as part of their expertise and discuss the pros and cons of each selection, as well as display experience in manufacturing it. Take a careful look at their industry standards and certifications, like the ISO9001:2015 AS9100D, to be sure that they understand the regulatory requirements for aerospace applications. Most importantly, look at the supplier's experience in manufacturing mission critical thermoplastic aerospace components, as many times the actual machining talent and experience is the difference between a failed or successful thermoplastic component.

In a field as mission-critical as aerospace, success often relies on choosing the material best suited for an application. Increasingly, that material is thermoplastic.

This article was written by John Macdonald, President, AIP Precision Machining (Daytona Beach, FL). For more information, visit here .