3D printing composites have revolutionized how we think about strength, rigidity, and thermal performance in additive manufacturing. Among them, glass fiber (GF) and carbon fiber (CF) reign supreme. While CF has long been a staple, GF is rapidly gaining ground—and for good reason.
Glass Fiber: The Underdog with Surprising Strength
Glass fiber is a silica-based, non-conductive additive that enhances tensile strength and printability. Unlike carbon fiber, which is stiffer but more brittle, GF materials offer a better balance of durability and flexibility. GF’s amorphous structure also means it’s denser and generally cheaper to produce.
In materials like GF PEEK, tensile strength is exceptional, and its printability is dramatically improved. GF transforms traditionally high-warp polymers into smooth-printing, dimensionally stable components. Even better, GF PEEK boasts a heat deflection temperature (HDT) of up to 302°C (575.6°F), making it the highest-rated plastic in some commercial portfolios.
Why Composites Matter in High-Performance Applications
Composites aren’t just about strength—they’re also about precision. The embedded fibers act like a scaffold within the polymer, reducing warping and improving layer-to-layer adhesion. This is critical for applications requiring dimensional stability, like aerospace ducting or under-the-hood automotive components.
Composites are already used in industries like firearms and injection molding, with CF ABS found in parts like radiator brackets. When metals aren’t suitable—such as in RF-transparent or non-magnetic environments—GF and CF composites are essential.
Real-World Example: CF PEEK in Formula 1
3D printing’s high-performance capabilities have reached the Formula 1 track. Racing Bulls F1 (a sister team to Red Bull Racing) leveraged CF PEEK to 3D print brake cooling ducts, achieving up to 68% savings in time and cost. And that’s just the beginning—teams are exploring more structural applications for additive technologies across the car’s chassis and internals.
The Additive Advantage
Traditional carbon fiber layup is labor-intensive: molds, resin, peel-ply, vacuum bags, and curing ovens. In contrast, 3D printing composites can yield functionally strong parts in a fraction of the time—with less waste and more design freedom. Internal geometries, lightweight lattice structures, and encapsulated chambers are now feasible at the desktop scale.
What’s Next? Graphene, Kevlar, and Beyond
The future of composite 3D printing could lie in advanced materials like graphene—known for its ultra-high strength, flexibility, conductivity, and transparency. While difficult to incorporate due to its atomic-scale structure, it holds promise for thermally and electrically conductive composites. Other options like Kevlar and hemp fiber have seen limited adoption, mostly due to lower strength-to-weight ratios or lack of market traction.
Not All Carbon Fiber Filaments Are Equal
Beware of marketing gimmicks. Many filaments labeled as “carbon fiber” are filled with powder rather than chopped fiber strands, which significantly diminishes their mechanical benefits. True performance requires carefully engineered formulations—and transparency in how those materials are made.
Combining Additives: The Ultimate Composite?
There’s speculation about combining GF, CF, graphene, and even flame-retardant or bio-based fibers into hybrid filaments. While that sounds like the “superfood” of 3D printing, it’s not yet widespread. But it’s an exciting area for material scientists and industrial innovators alike.
Final Thoughts
Glass fiber and carbon fiber composites are transforming additive manufacturing from a prototyping tool into a serious production method. With growing applications in motorsports, aerospace, and beyond, the trend is clear: if performance matters, composites are the future. And with ongoing innovation in materials like graphene, we’re only scratching the surface.
Need help choosing the right high-performance 3D printing solution? Whether you’re printing ducting, brackets, or heat-resistant enclosures, our team is ready to support your journey into advanced manufacturing.