Both fiber reinforced thermoplastics (FRT) and carbon fiber reinforced polymers (CFRP) are used extensively in aerospace manufacturing. FRTs have some definite advantages over CFRPs, which is why their use is expanding. But they also have their disadvantages. For example, scaling up FRT production comes with its challenges.
Although FRTs and CFRPs are types of composites with many similarities, they are not identical. The biggest difference between them lies in their distinct resin matrices. FRTs are thermoplastic polymers that can be melted and molded into new parts. They are also more easily recycled compared to capital CFRPs. That is one of the reasons they are so attractive to aerospace manufacturing.
CFRPs rely on thermosetting resins for their matrices. They offer the high strength-to-weight ratio and stiffness aerospace design requires. However, they are much more difficult to recycle. As aerospace composites move toward a more sustainable manufacturing model, FRTs are more favorable.
The challenges that come was scaling up FRT production in aerospace have slowed FRT adoption in recent years. Overcoming the challenges could make an enormous difference in the overall aerospace composites picture. What are those challenges? Here are the five most common:
Thermoplastic manufacturing is a high-temperature enterprise. It requires temperatures of 300-400°C. By comparison, manufacturing thermosets involves temperatures no higher than about 180°C.
Higher temperatures mean upgraded tooling and equipment. They also mean increased energy costs and the associated regulations. Finally, prolonged exposure to high temperatures tends to degrade polymer matrices, making quality control more difficult.
Scaling up FRT production ultimately requires process adaptation. As you might expect, adapting existing processes doesn’t come without a cost. Process adaptation takes time and costs money. It also requires new ways of managing quality control. Everything from material handling to final part inspection needs to be modified to accommodate scaling.
Supply chain limitations can make FRT scaling more difficult for the simple fact that manufacturers may not be able to get their hands on the materials they need. Thermoplastic prepregs are a good example. The limited availability of such prepregs can stall efforts to scale up. In addition, thermoplastics are more expensive than their thermoset counterparts. Higher costs and limited availability can make scaling up cost prohibitive.
Materials need to be certified before they can be used for aerospace applications. Unfortunately, thermoplastics often struggle to meet NCAMP certification standards. Manufacturers need to go to great lengths to solve that problem before FRTs can be adopted for structural components.
Although FRTs are more easily recycled than their CFRP counterparts, there are sustainability issues to consider. First and foremost are the higher energy demands FRT manufacturing requires. Excessive energy consumption does not fit well into the sustainability mindset.
In terms of recycling, manufacturers need the infrastructure and waste management capabilities to handle it effectively. Currently, both infrastructure and waste management are lacking. Scaling up requires providing both at an additional cost.
Assuming future FRTs can be manufactured from the ground up to meet certification standards, scaling up production for aerospace applications is worth the time, expense, and effort. But until that day arrives, aerospace composites will continue to be mostly thermoset products.
Now is a great time to be involved in aerospace composites. Between FRTs and capital CFRPs, composites are literally driving the future of aerospace. New and better materials will ultimately lead to better and more productive aerospace components. And who knows where they will eventually lead us?
