Fiber-reinforced plastics (FRPs) are composite materials made up of a polymer matrix reinforced with fiber. The unique combination of physical properties in FRPs can significantly improve 3D-printed parts and prototypes.
Improvements in mechanical properties, such as strength and durability, can be achieved while also maintaining lighter weight and achieving shorter production times.
This unique combination of properties makes FRP ideally suited for applications including infrastructure and construction, aerospace, automotive, and sporting goods.
What is 3D Printing?
3D printing, also known as additive manufacturing, allows the production of three-dimensional solid objects from a digital design file. Software is used to create a digital model. The digital model is then digitally “sliced” into many layers. The digitized slices are then sent to a 3D printer.
The most common 3D printing method is fused filament fabrication, also known as fused deposition modeling (FDM), in which a filament of modeling material is fed through an extrusion nozzle and deposited onto a modeling platform. FDM takes a top-down approach to 3D printing.
Vat polymerization takes a bottom-up approach - a photopolymerizable resin is stored in a vat and exposed to a UV light source. The cured 3D structure is raised incrementally as new layers are added to the bottom of the printed model. Vat polymerization techniques like stereolithography offer higher precision and better print quality, as the small size of the laser light source enables finer detail and higher resolution.
Another common technique is selective laser sintering (SLS). In SLS, a powder-based printing material is spread over a build platform. A UV light source then selectively sinters the powder to form a layer of the model. After a layer is sintered, the build platform shifts downward, another layer of powder is applied, and the process repeats until the three-dimensional object is complete.
Why Use 3D Printing?
Additive manufacturing has been used for rapid prototyping since the mid-1980s. Design engineers quickly adopted the technique to increase efficiency during product development. In-house engineers can make dozens of iterations of a design if they choose, and the design gets better each time. The real cost-benefit was realized in the savings in tooling costs that naturally followed from adopting this technology.
As technology has matured over the years, 3D printing has moved beyond rapid prototyping and into the commercial production of goods across many sectors, including automotive and aerospace.
Swedish car manufacturer Koenigsegg employed 3D printing to produce both metal and plastic parts for the turbocharger and exhaust systems of its One:1 model. Additive manufacturing was also used to produce features such as pedals, footrests, and mirror housings. The potential for waste and weight reduction made 3D printing an attractive alternative to traditional manufacturing methods.
Airbus chose 3D printing for similar reasons. More than 1,000 parts on the Airbus A350XWB were produced using this technique. Airbus employed printers manufactured by Stratasys, which characterized its use of 3D printing as unprecedented in scale. Similarly, a collaborative effort between General Electric and the Air Force employed 3D printing during the development and production of parts for the GE F110 engine, which powers the F-16 jet fighter.
Thermosetting Resins in 3D Printing
Polymeric matrices in composite materials are either thermoplastics or thermosets. Thermoplastic resins are used in many 3D printing applications. However, thermoset matrices offer higher strength and heat resistance and often have higher fatigue strength and finishing qualities relative to thermoplastics. These characteristics make thermoset resins attractive candidates for structural and electrical applications, civil engineering, appliances, and commercial and residential construction.
The use of thermosetting materials in extrusion-based additive manufacturing methods, such as FDM, poses challenges in controlling viscosity during deposition and curing. This is essential to maintaining the three-dimensional geometry of printed objects.
Because rapid curing is required after material deposition, most thermoset FRP materials used in 3D printing applications have an injection/cure temperature below 100°C and a short cure time.
Arkema’s Sartomer division recently launched the N3xtDimension® line of liquid resins for UV-curable additive manufacturing. The N3xtDimension® resins aim to bridge the gap between traditional thermosetting resin technology and emerging 3D printing technology. This product line is suitable for use in vat polymerization, selective laser sintering, and filament extrusion applications.
Significant advances are being made in developing both equipment and materials to address these challenges and enable more widespread use of fiber-reinforced thermoset composites in extrusion-based 3D printing.
3D Printing with FRPs
FRP composites are already in use in both commercial and military aircraft. The automotive industry has long used FRP as a substitute for steel, aluminum, and other metals due to its ideal strength-to-weight ratio. Pultruded FRP applications for the automotive sector include various beams, front-end support systems, chassis rails, and transmission tunnels.
It seems natural, then, to combine the strength and weight benefits of FRP with the potential for improved efficiency and reduced manufacturing costs that can be realized through 3D printing during both R&D and production.
A joint effort between the University of Delaware and Dunghua University in Shanghai recently developed a 3D printer with a capillary-driven printing head and an automated robotic arm, enabling the printing of thermosetting FRPs. The 3D printed FRPs based on epoxy resin and continuous carbon fiber had a degree of curing of 95%, included a high fiber volume fraction (58.6%), and exhibited excellent physical properties, including a mechanical strength of 810 MPa and modulus of 108 GPa.
A recent literature review shows that research and development of 3D printing technology for thermoset FRPs has accelerated. The bulk of current research focuses on composite materials based on epoxy and phenol-formaldehyde resins, combined with both short and continuous carbon, glass, and aramid fibers.
Experimental data show that 3D-printed thermoset FRP composites manufactured using a variety of techniques exhibit mechanical behavior comparable to that of aluminum and steel alloys while maintaining significantly lower weight.
The Future of FRP 3D Printing
Additive manufacturing technology opens the door to materials with new and enhanced mechanical properties, lightweight composition, and greater flexibility with the potential for lower manufacturing costs and rapid production. The future for 3D-printed FRP parts and products is bright, with significant innovation on the horizon.
FPR is our business here at Tencom, and we’re excited to work with you to discover new applications, growth, and development. If you’d like to explore how FRP can help improve your products, please get in touch.
