As reported by MarketsandMarkets, the global aerospace composites market is expected to surpass $50 billion by 2030, primarily driven by the ongoing trend towards lightweight thermoplastic materials, which can lightweight a plane by up to 20-30% in weight reduction when compared to traditional aluminum structures.
The debate over thermoplastic composites versus thermosets will continue to lead the way for the future of aircraft manufacturing while directly affecting everything from weight, cost savings, and fuel efficiency to reparability and lifecycle costs. So how do you know which composite is the best choice for your application?
WM F McGraw & Co. is an expert in aerospace-grade materials and fabrication in Riverview and has assisted aerospace engineers, manufacturers, and defense contractors through various aspects of selecting the right composite for each structural and performance requirement.
Understanding the Basics: Thermoplastic vs Thermoset Composites
What are Thermoset Composites?
Thermoset composites are made using a polymer resin that can be permanently set when cured with heat or through a chemical reaction. Once cured, thermoset composites cannot be remolded or reheated. Thermosets are no stranger to aerospace materials as they have imposed their dominance in the aerospace industry due to their high stiffness, dimensional stability, and ability to withstand extreme heat and cold, rendering them highly qualified for structural components like fuselage sections, wing skins, and engine nacelles, where high rigidity and thermal functioning are critically required.
Due to their cured state, thermosets comprise a high cross-linking of the molecular structure, allowing the component to maintain high strength under high loads.
What are Thermoplastic Composites?
Thermoplastic composites, however, are made of polymer resins that soften when heated and harden when cooled, allowing multiple reshapes without losing integrity. This adaptability makes thermoplastics a more flexible platform for manufacturing and repair processes.
As such, thermoplastics are more attractive to aerospace engineers because they can be rapidly processed with less production waste, and if the part is made of thermoplastics, it can be reheated to weld the part together, effectively reducing the amount of time it will be out of repair, subsequently reducing TAT (turnaround time).
The Core Differences: Thermoplastic vs Thermoset Aerospace Composites
Concerning the performance characteristics of thermoplastic vs thermoset aerospace composites, thermosets typically have better heat resistance and good dimensional stability and are therefore better used in areas of high temperature and high load. Further, thermoplastics excel in impact resistance, fatigue performance, and toughness, and therefore are recommended for secondary structures or interior components.
Strength, Weight, and Durability
- When determining whether a material is appropriate in aerospace engineering, the strength-to-weight ratio of the material is an important component in your evaluation.
- Historically, thermoset composites have dominated: the very stiff, cross-linked nature of the materials acts as a load-bearing member.
- The performance gap between thermoplastics and thermosets has shrunk due to advancements in thermoplastic resin systems, such as PEEK (Polyether Ether Ketone), PPS (Polyphenylene Sulfide), and others.
- One of the key distinctions between thermoset and thermoplastic resins is their durability; thermoset resins do not recover shape with increased temperature, whereas thermoplastic resins remain durable under load in increased temperature conditions.
- Thermoplastics absorb more energy and are better at preventing crack propagation, and are a safer and more reliable material for dynamic aerospace conditions.
Manufacturing and Processing Efficiency
- Effectiveness in manufacturing is an important factor when comparing aerospace materials.
- Thermoset composites require a cure time of two to four hours, while still being required to be made in an autoclave or special oven, which lengthens the manufacturing time and increases energy consumption.
- These factors all add to the time-consuming nature of thermoset composites for contract suppliers when making components for aerospace systems.
- In contrast, thermoplastic composites are much easier and faster to manufacture using methods such as compression molding, direct injection molding, and automated fiber placement (AFP).
- Their speed of manufacture is limited mostly to cooling and heat integrity, but there is no lengthy cure time.
- Thermoplastics can also be reheated to different shapes and can also be connected using fused bonding instead of adhesives, all of which reduces steps for assembly.
As a result of these factors, thermoplastic composites will also help to shorten manufacturing time, get to higher throughput, and reduce costs, all being key strategies for aerospace OEMs and suppliers implementing Lean manufacturing goals.
Repairability and Recyclability
Maintenance and lifecycle management are also important considerations for aerospace materials that employ fiber composites.
- The high strength and durability of thermoset composites usually equate to an entire component replacement when a structural crack occurs, which is a time-consuming and expensive means of repair.
- On the other hand, thermoplastic composites can be brought and reheated to different shapes in the field, which would reduce downtime for repair.
- This in-field repair promotes sustainability in lifecycle management by increasing the component life and decreasing waste from the components.
- Thermoplastics are also recyclable polymers and provide an even greater sustainability advantage as aerospace continues to transition to greener manufacturing solutions and end-of-life solutions.
- Thermosets, on the other hand, cannot able to be melted and reused due to the irreversible cure process; therefore, their potential for sustainability is limited.
Cost Considerations and Lifecycle Value
While understanding the aerospace materials comparison, thermoset materials may often be less expensive at the beginning of a lifecycle, long processing times and limited repairability can add costs down the line. While thermoplastics may approach greater expense initially, production time savings, repair flexibility, and recyclability result in savings in both time and material for the customer.
Thermosets are still preferred for small-batch manufacturing or high-heat applications; however, the commercial aviation sector also seems to be gravitating toward thermoplastics for volume and performance.
What are the New Ideas & Scope for Aerospace Composites?
Choosing a manufacturer to go with thermoplastic or thermoset composites is not a matter of one being superior or inferior; it is a matter of fit for purpose. Thermoset composites can’t be beaten for their stiffness and thermal stability, while thermoplastic composites offer flexibility, impact resistance, and resource sustainability.
Selecting a composite, whether thermoplastic or thermoset, is based on the application for aerospace, the projected design situation, and manufacturing objectives. The aerospace goal is to go lighter, go faster, and go green, and it’s evident that thermoplastic composites most likely will lead the next generation of aerospace manufacturing.
WM F McGraw & Co. is a reputable name in aerospace material selection, composites, design, and engineering innovation. With decades of successful supply, fabrication, and consulting experience surrounding advanced aerospace materials and composites, we help manufacturers make informed, performance-based decisions for their next project.
FAQ on Selecting the Best Materials: Thermoplastics vs Thermoset Composites for Aerospace
1. What is the difference between thermoplastic and thermoset composites in aviation uses?
The primary difference is their behavior when exposed to heat and how the difference affects their reformability. Thermoset composites have an irreversible curing process, rendering them rigid and relatively heat-resistant, but they cannot be reformed. Thermoplastic composites remain below their melting temperature, can be reheated, reshaped, and welded multiple times without losing integrity.
2. Which composite is better for high-temperature aerospace applications?
Thermoset composites are preferred in high-temperature environments due to their heat and dimensional stability. Their cross-linked molecular structure provides strength, rigidity, and dimensional stability when subjected to thermal and mechanical stress.
3. Why are thermoplastics more widely used in the aerospace manufacturing sector?
Thermoplastics are more widely used in the aerospace manufacturing sector as they allow for faster production rates, lower energy costs, and an easier repair process. Likewise, thermoplastics support sustainability goals as they are typically not only more readily recyclable or reusable, which is an important characteristic to consider in a next-generation aerospace manufacturing approach.
4. Will thermoplastic composites totally replace thermoset composites in the design of aircraft?
Not totally replace, but thermoplastics, while still requiring thermoset composites to meet primary load-bearing and high-heat structural applications in aircraft, are gaining traction. While thermoplastics remain the specialty of choice for structural applications, typically, thermoplastic composites are used in secondary structure, interior parts of an aircraft, or any part that requires impact resistance, flexibility, and cost-effective manufacturing.
5. How does WM F McGraw & Co. in Riverview support alternative aerospace material selection?
WM F McGraw & Co. in Riverview can provide quality leadership in aerospace material selection and composites. Our team assists manufacturers and product developers with selecting materials that meet the desired balance of performance, durability, and cost.
If you would like to receive more information about your thermoplastic vs thermoset aerospace composites, feel free to contact us.
