Advancing Composites in Large Format Additive Manufacturing

Understand the baseline of composite polymers, different types of composite materials for LFAM, and how Pellet 3D Printing enables them.

By Ben Toomey
February 16, 2025

At the turn of each year, our team evaluates trends within large-format additive manufacturing (LFAM) and the broader manufacturing landscape. We look at everything from customer conversations to industry reports to understand where growth is likely to accelerate or stall.

Across those discussions, one signal became clear. Reinforced composite materials are seeing increased demand in LFAM environments.

As Pellet 3D Printing (Fused Granulate Fabrication) continues to gain adoption across aerospace, rail, marine, and industrial tooling, material development is advancing alongside it. While they’ve always had their place, reinforced composites are undoubtedly the most prevalent types of materials used in LFAM. At scale, they are becoming necessary to achieve predictable mechanical performance and dimensional stability.

The need for Composite Materials in LFAM

Large-format additive manufacturing differs from desktop printing in more than part size. As parts increase in scale, material behavior becomes more critical. Comparatively, unfilled polymers reach performance limits quickly when exposed to thermal cycling, mechanical loading, and long build times. Warping, delamination, creep, and dimensional inconsistency become more common as geometry increases.

Reinforced composite materials address these challenges by combining agents into a base polymer that improves behavior during both printing and service. The results can include improved stiffness, better dimensional stability, higher strength-to-weight ratio, and greater structural reliability.

Polymer Reinforcements: A Baseline

Fiber Reinforcement

Fiber reinforcement remains the most common method for increasing stiffness and strength in polymer composites. Fibers are commonly carbon, glass, aramids, or natural materials. They may be introduced in discontinuous or continuous form.

Chopped Fiber Reinforcement

Chopped fiber reinforcement is commonly used in pellet-fed LFAM systems such as our Tradesman Series™ P3-44. Discontinuous fibers are compounded into the polymer matrix, resulting in a composite that strikes a balance between structural performance and processability.

Chopped fiber-reinforced composites are generally more cost-effective to manufacture than continuous fiber composites. There are also many different types of resins used to create chopped fiber-reinforced composites, making it easier to find a suitable option tailored for the application. Since the fibers are bound by the polymer matrix, chopped fiber-reinforced composites also allow for a higher degree of flexibility in shaping and forming complex geometries during manufacturing. This is what we typically see in pellet-fed 3D printing.

Continuous Fiber Reinforcement

In continuous fiber reinforcement, composite materials use long, uninterrupted fibers that run through the entire length of the material. In this technique, fibers such as carbon, glass, or aramid are aligned parallel to each other and embedded within a polymer matrix.

Consider how Rebar is added to concrete structures to enhance their structural integrity. Just as the Rebar is introduced as a load-bearing element, continuous fiber reinforcement adds long, unbroken strands to improve durability.

3D printing with continuous fiber requires specialized knowledge, equipment, and software to utilize effectively. Working with continuous fibers requires careful placement and can be more complex, making the process more intricate, time-consuming, and costly. It can be very useful for the right applications, specifically where high stiffness, strength, and directional properties are crucial.

Looking into Other Composite Materials for LFAM

The good stuff.

With a myriad of base polymers, there is an ever-evolving list of agents and additives tailored to the needs of LFAM users. Each reinforcement serves a different role, dependent on the final part’s parameters and capabilities:

Carbon Fiber

Carbon Fiber is often chopped and laid into the polymer matrix at varying levels (often 10%-20%). Carbon Fiber Reinforced composites often benefit base polymers by displaying exceptional strength, high stiffness, and low weight. Aerospace, Aviation, and Defense verticals benefit largely from the use of carbon fiber due to its weight-to-strength ratio. We tend to see these reinforced into commodity materials such as ABS (Acrylonitrile Butadiene Styrene), all the way up to autoclave rated materials like PEI (Polyetherimide).

Glass Fiber

Cost reduction, resistance to corrosion. Glass tends to increase the density of the material, aiding in dimensional stability, but has a trade-off when it comes to challenges of steeper overhangs deeper into the print.

Natural Fiber Composites

Often found with Hemp, Wood Flour, or cellulose to offer an eco-friendly alternative to synthetic reinforcement. The use of natural fibers can be tied to cost-reduction or conservation efforts. Our internal team has worked with wood flour PETG with the University of Maine’s Advanced Composites and Structures Center (ASCC) to use additional waste from the logging industry in the northeast.

Metal Impregnated Composites Polymers

Rather than fibers, powder is compounded into the base polymer. Metals, such as Tungsten, are tested to increase properties that benefit shielding applications. Though brittle, the materials themselves contain desirable properties applicable to the field.

Nanoparticle Composites

Nanomaterials commonly used to reinforce polymers, like carbon nanotubes (CNTs), are like many fibers in the fact that they are both high-strength and lightweight. However, nanoparticles are significantly smaller in scale and structure, and while conventional fibers may be superior for structural reinforcement, nanomaterials offer superior performance for other properties, such as thermal conductivity, flame resistance, or electrical conductivity. The continued adoption and testing of these materials are to benefit industry or application compliant parts (ex: ESD/FR Compliance).

How Does Pellet 3D Printing Enable a Wide Array of Materials?

Pellet 3D Printers enable the use of lower-cost feedstocks and industrial agents. Composite materials must undergo additional processes to be converted into filament, which could compromise the material’s properties. Additionally, filament production limits the variety of composite materials that can be used. For instance, most composite fiber loading is limited by the filament production process. As pellets, composite materials can be formulated to meet specific application needs rather than compromising designs to fit a narrow material set.

The value in this is immeasurable. The convergence of material science and machine capability becomes an instant enabler for those across industries where part performance is paramount.

Internally, our team provides a Material Testing & Assessment procedure to validate materials as “printable”, developing process parameters on our large format additive systems. Working in tandem with material companies looking to bring their newly developed materials to the market drives cohesion between the OEM and developers to meet customer needs.

Composite Materials For Large Format: A Summary

Reinforced composite materials in LFAM extend far beyond fiber reinforcement alone. By combining polymer matrices with fibers, fillers, powders, and functional additives, manufacturers can tailor material behavior to meet application requirements.

As industry needs continue to expand, reinforced composites meet a necessary need for those looking to bring production into the next generation of advanced manufacturing.