Composite materials, such as Carbon Fiber-Reinforced Plastics, are versatile and high-performance materials driving innovation across various industries, from aerospace to medical. These materials outperform traditional options like steel, aluminum, wood, or plastic, enabling the production of lightweight, high-performance products.

In this guide, you will learn the basics of carbon fiber part manufacturing, including various methods for carbon fiber layup, lamination, and molding. You will also discover how to leverage 3D printing technology to create carbon fiber molds, reducing costs and saving time.

Additionally, there are directly 3D printable composite materials, such as Formlabs Nylon 11 CF Powder, a carbon fiber-filled material ideal for applications requiring both high strength and stiffness. When printed with the Formlabs Fuse 1+ 30W, Nylon 11 CF Powder produces lightweight, dimensionally stable, structurally and thermally stable parts that can withstand repeated impacts.

Introduction to Composite Materials 101

Composite materials are combinations of two or more materials that, when combined, exhibit properties different from those of the individual components. Generally, engineering properties such as strength, performance, or durability are enhanced. Composites consist of a reinforcement material, which can be fibers or particles, and a matrix material that binds them together. The matrix can be a polymer, metal, or ceramic.

Fiber-Reinforced Polymers (FRPs) dominate the market and are key drivers for new applications across various industries. Among these, carbon fiber is a widely used composite material, particularly in aerospace, racing cars, and bicycles, due to its strength and stiffness being more than 3 times that of aluminum, while being 40% lighter. Carbon fiber is made from reinforcing carbon fibers bonded together with epoxy resin.

Fibers can be arranged unidirectionally (Uni-Weave) and strategically aligned to create strength in the direction of the force (vector). Additionally, cross-woven fibers can be used to create multi-directional strength, which is also responsible for the distinctive quilted pattern of composite parts. Typically, parts are manufactured by combining both types of fibers.

Currently, several types of fibers are available:

Resins are used to bind these fibers together and create strong composite materials. While hundreds of resin types can be used, the most popular types are listed below:

3 Methods for Creating Carbon Fiber Parts

Manufacturing Fiber-Reinforced Polymers, such as carbon fiber parts, is a highly skilled and labor-intensive process, whether for single parts or series production. Cycle times can range from 1 hour to 150 hours, depending on the size and complexity of the part.

Typically, in FRP manufacturing, continuous straight fibers are embedded within a matrix to form individual material layers (plies), which are then laminated layer by layer onto the final part.

The properties of composite materials are not solely determined by the material itself but also by the lamination process. The way fibers are arranged and bonded significantly impacts the part's performance. Thermoset resins are molded with reinforcement materials within a tool or mold and undergo a curing process to create a durable, strong product.

There are several lamination techniques, which can be divided into three main categories:

1. Wet Lay-Up

In a wet lay-up, fibers are cut and placed into a mold, and then resin is applied with a brush, roller, or spray gun. This method requires the most skill to create high-quality parts but is also the lowest-cost process and has the lowest barrier to entry for DIY carbon fiber part production.

If you are new to carbon fiber part manufacturing and do not have all the necessary equipment, we recommend starting with a wet lay-up lamination.

2. Prepreg Lamination

In prepreg lamination, the resin is pre-impregnated into the fibers. These pre-impregnated sheets are stored at low temperatures to slow down the curing process.

The plies are then cured within a mold under heat and pressure inside an autoclave.

This method offers greater precision and repeatability as the resin quantity can be precisely controlled, but it is also the most expensive technique and is often used in high-performance applications.

3. Resin Transfer Molding (RTM)

In RTM, dry fibers are placed into a two-piece mold. The mold is then closed and clamped tightly before resin is injected into the mold cavity under high pressure.

This process is often automated and commonly used for high-volume production.

Creating Molds for Carbon Fiber Parts with 3D Printing

Since mold quality directly affects the final part quality, tool making is a critical part of FRP manufacturing.

Most molds are made from wax, foam, wood, plastic, or metal through CNC machining or manual processes. While manual methods are labor-intensive, CNC machining is still a complex and time-consuming process, especially for complex geometries. Outsourcing often comes with high costs and long lead times. Both methods require skilled labor and offer little flexibility for design iterations or mold customization.

Additive manufacturing provides an alternative for rapid, low-cost mold and prototype production. For carbon fiber part creation, the use of polymer tools in manufacturing processes is continuously growing.

Replacing metal tooling with in-house 3D printed plastic parts is a powerful and cost-effective way to reduce lead times and increase design flexibility. Engineers currently use 3D printed resin parts for creating jigs and fixtures to support processes such as filament winding or automated fiber placement.

Similarly, 3D printed molds and dies for short-run production are also used in injection molding, thermoforming, or sheet metal forming to support low-volume production.

In-house desktop 3D printing requires minimal equipment and simplifies workflows. Professional desktop resin printers like the Form 4 are affordable, easy to set up, and can scale production quickly as needed.

Additionally, large-scale tools and molds can be produced with large-format 3D printers like the Form 4L.

Stereolithography (SLA) 3D printing technology can create parts with very smooth surfaces, a crucial property for carbon fiber layup molds. It also supports the creation of complex geometries with high precision.

Furthermore, Formlabs' resin material library includes engineering resins with mechanical properties and heat resistance ideal for producing molds and prototypes.

3D printed molds for carbon fiber part production can reduce costs and manufacturing time.

For small-scale production, engineers can directly print molds at low cost and in just a few hours, eliminating the need for manual carving or dealing with CNC equipment, CAM software, machine setup, workholding systems, cutting tools, or chip management.

Labor and mold production time are significantly reduced, allowing for rapid design iterations and part customization. It also enables the creation of complex and intricate mold geometries that are difficult to produce with traditional methods.

Mold Design and Structure Guidelines

When designing a mold, you should consider both successful printing and the ability to fully form the part. Each mold structure is used to create different shapes, as follows:

One-part mold for vacuum bagging:
Used for parts requiring only one Class A surface, meaning a smooth, polished surface. The mold can be positive or negative, depending on which side needs to be a Class A surface. One side will be the mold surface, and the other will be the vacuum bag surface.

Two-part mold for compression molding:
Used for parts requiring Class A surfaces on both sides. Both sides of the part will contact the mold surface.

Bladder mold for pressure molding:
Used for complex parts that cannot use a vacuum bag or compression mold because the part cannot be removed from the mold. One side will be the mold surface, and the other will be the bladder surface.

Mold pattern to create a negative mold:
Used when multiple molds are needed to increase production capacity. Multiple molds can be created from the same pattern.

	Add Draft Angle: A positive draft angle of approximately 2–3 degrees facilitates part removal from the mold (demolding) and extends mold lifespan, especially for high-stiffness molds. However, using flexible 3D printing materials like Tough 1500 Resin allows you to create parts without a draft angle and even form complex geometries that cannot be removed from typical rigid molds. Define Minimum Radius appropriate for material thickness: This helps fibers conform better to angles, reduces air bubbles, and ensures consistent quality parts. Avoid tight, steep, and closely spaced angles, as flowing curved shapes are easier to work with than boxy or sharp-cornered shapes.
	Define Minimum Radius appropriate for material thickness: This helps fibers conform better to angles, reduces trapped air bubbles, and ensures consistent quality parts. Avoid steep and closely spaced angles, as flowing curved shapes are easier to work with than boxy or sharp-cornered shapes.
	Add Locating Pins and Indents for molds requiring precise alignment. One significant advantage of 3D printing is the ability to create complex alignment features, making it easier to produce designs requiring precise positioning. Add Surface Overrun: Excess material from the protruding surface will be trimmed later to create an accurate trim line. 3D printing allows this excess to be created without producing flashing. Add Trim Lines: 3D printing allows the integration of precise finishing details, such as drilling guides, hand-trimming lines, or router guides.

Other Best Practices:

Print with the smallest possible layer height to increase part resolution and facilitate demolding.

Avoid using supports on the mold surface for a smoother finish.

Use Release Agent: This is essential to help remove the part from the mold.

To avoid trapped air bubbles: After stirring and mixing the resin, wait approximately 2 minutes for air to rise out of the resin. Then repeat after brushing on the first layer of resin. If small air bubbles remain, they can be sanded and sealed during post-processing.

Case Study: TU Berlin Uses 3D Printing for Carbon Fiber Molds

Formula Student is an annual engineering design competition where student teams from around the world design, build, and race formula-style cars.

The TU Berlin Formula Student team (FaSTTUBe) is one of the larger teams, with approximately 80 to 90 students who have been jointly developing new race cars every year since 2005.

The TU Berlin Formula Student team (FaSTTUBe) is building three race cars for the annual Formula Student competition.

With access to nearly all types of manufacturing technologies, the FaSTTUBe team uses 3D printing in three ways:

Prototypes:
The team prints prototypes for various parts, such as anti-roll bar mountings or high-voltage battery stakeholders.

3D Printed Carbon Fiber Molds:
The team has printed approximately a dozen molds to produce carbon fiber parts that cannot be manufactured by other means.

End-use Parts:
About 30 parts on the actual race car are directly 3D printed, ranging from control button mounts, steering wheel shifters, to cooling system pipes and sensor connectors.

In this case study, we will delve into the details of the molds the team used to produce the carbon fiber steering wheel frame and grips.

Weight reduction is crucial in building a race car. The team could print hollow steering wheel grips, but such parts would not be strong enough to withstand the driver's grip.

Carbon fiber is an excellent material for reducing weight while maintaining or increasing strength.

To enable carbon fiber part production this year, Felix Hilken, Head of Aerodynamics and Carbon Manufacturing, developed a workflow using 3D printed molds for wet lay-up lamination.

Required Equipment:

Formlabs SLA 3D printer with Tough 1500 Resin

Carbon Fiber: 3 layers, 200g, 3K, 0.3mm thickness, Twill Weave pattern

Mold Release Agent: Wax and Polyvinyl Alcohol

High-strength epoxy resin

Brushes and scissors

Vacuum Bag, vacuum pump, and breather cloth

Sandpaper

	Design the mold The grips were produced in two parts to allow part removal from the mold. For each grip half, Felix designed a two-piece mold, adding details that would be difficult to produce without 3D printing, specifically: Small details such as narrow internal radii, continuous curved surfaces, or surfaces with varying radii. Narrow curved edges that cannot be removed from aluminum molds. Locating grooves for drilling, as this part is highly sensitive to positioning.
	3D print the mold The team 3D printed the mold using a Form Series printer and Tough 1500 Resin at a layer height of 50 microns. The printed parts were washed with IPA twice, 10 minutes each time, and then post-cured for 60 minutes at 70°C. The team chose Tough 1500 Resin because this material offers a good balance between elongation and modulus. Parts printed with this material can bend significantly and quickly return to their original shape. These mechanical properties are desirable to help prevent mold breakage during the demolding process.
	3.1 Hand Lamination: Apply Release Agent Apply a release agent to help easily remove the part from the mold. This is a crucial first step. If any surface area is not coated, the part will not separate from the mold. Wax coating — an optional but recommended step. Polyvinyl Alcohol (PVA) coating.
	3.2 Mix Resin and Hardener Mix the resin with the hardener. The mixing ratio must be precise. If the ratio deviates from the specified value by even a few percent, the part may be too soft or may not fully cure. Strictly follow the resin manufacturer's recommendations and read the Safety Data Sheet before use. For the resin Felix used, polymerization begins approximately two hours after mixing, meaning there are two hours available for the layup operation.
	3.3 Apply Resin Brush the resin onto the positive side of the mold.
	3.4 Lay-Up Carbon Fiber Place the carbon fiber ply onto the positive side of the mold, ensuring the fibers conform perfectly to all surfaces and geometries. The team chose 3K weave to balance weave thickness and cost. This material is specifically designed to conform to complex shapes and does not contain supporting strands within the material.
	3.5 Apply Resin to Carbon Fiber Apply resin to the carbon ply and repeat the layup process. The resin binds the layers together, forming the matrix component within the part, and helps prevent fiber movement or misalignment. Felix used a total of 3 carbon fiber plies.
	3.6 Apply Final Resin to Negative Apply the final layer of resin to the negative part of the mold. Then, assemble both halves of the mold to prevent air bubbles and air infiltration through the carbon fibers.
	3.7 Trim Excess Material Use scissors to cut off excess material from the part.
	3.8 Cure Cure in a vacuum bag for 48 hours. During the polymerization process, the vacuum bag removes air and presses the plies against the mold at room temperature to eliminate excess resin. This process helps achieve the desired resin-to-fiber ratio, ensuring the part has optimal stiffness.
	Post-Process and Finish Finishing: Trim all edges. To clean the mold after the process, Felix soaked it in water for about 30 minutes to dissolve the PVA, then used 1500 grit sandpaper to remove any remaining resin.

Results

By using carbon fiber, the team was able to reduce the weight of the steering wheel frame from 120g to just 21g, and also design complex shapes that would be extremely difficult to produce with traditional methods.

“The great advantage of 3D printing is that complex shapes can be produced as easily as simple shapes, using the same amount of work and equipment,” Felix said.

Without 3D printing, the team would have had to outsource aluminum mold production using CNC machining, which is costly, time-consuming, and requires specialized tools.

“If I were to make molds with CNC, I would have to find specialized tools and wait for machine availability. Even then, I still couldn't make this shape, especially some small angles. I would need to change the design to eliminate screws, so the part wouldn’t be sensitive to alignment.”

He estimates that one mold printed with Tough 1500 Resin can produce approximately 10 parts.

Since this is a manual process, the actual lifespan depends on the carefulness of the operator, as molds can break during the demolding process.

However, multiple 3D printed molds can be used to increase production capacity. Another approach to extend mold lifespan is to use a conventional metal mold to support the structure.

The 3D printed insert would create the detailed shape, while the outer metal mold would maintain the form and support the forces, which can be produced using a typical manual milling machine.

Case Study: Panoz Automotive Carbon Fiber Parts

DeltaWing Manufacturing produces composite parts for Panoz, a designer and manufacturer of limited-edition American luxury sports cars.

Originally, to produce carbon fiber parts, DeltaWing Manufacturing would CNC machine a pattern, then lay up or cast a mold onto that pattern, and then finish the mold before entering the prepreg process to laminate the carbon fiber parts.

In recent years, they have begun to incorporate in-house 3D printed parts as an intermediate step in this process.

Panoz required six carbon fiber fender air ducts for a custom race car.

To reduce labor and production time from the traditional mold-making process, DeltaWing Manufacturing engineers chose to directly 3D print the molds and use them in their prepreg process.

Required equipment:

1. Formlabs SLA 3D printer with High Temp Resin
2. Carbon fiber: 4K bidirectional pattern
3. Release agent: Polyvinyl Alcohol
4. Kapton tape (Polyimide Tape)
5. High-strength epoxy resin
6. Brushes and scissors
7. Vacuum bag and vacuum pump

	Mold Design The air ducts were produced as two separate pieces on different molds to facilitate easy removal of the final parts from the molds, and then assembled and secured together. Each mold was also printed in two pieces and then reassembled to fit within the build volume of the Form Series printer. However, if a Form 4L printer with a larger build volume were used, this segmentation would not be necessary. All parts were designed for additive manufacturing, following recommended mold design guidelines.
	3D Printing the Molds DeltaWing printed the molds using High Temp Resin on a Form Series printer at a layer height of 100 microns. This resin was chosen due to its high Heat Deflection Temperature (HDT) of 238°C @ 0.45 MPa, which is the highest among Formlabs resins and also very high compared to resins generally available on the market. High Temp Resin can withstand the high temperatures of the curing process, has sufficient rigidity to maintain its shape throughout the operation, and provides excellent surface detail, which will be transferred to the final part. Formlabs recommends washing High Temp Resin parts with IPA for 10 minutes, then post-curing at 80°C for 120 minutes, and then oven-baking the parts at 160°C for 3 hours to further increase the HDT.
	Prepreg Lamination DeltaWing Manufacturing used their standard prepreg process on the 3D printed molds, employing 4K bidirectional prepreg carbon fiber. Each mold was covered with Kapton tape to allow for fresh surface renewal in each molding cycle. The fiber layers were then laid up onto the mold before the part was placed in a vacuum bag and cured in an autoclave. The part was then demolded and trimmed. The printed molds could withstand a slow cure process at 38°C (100°F) for 10 hours, or alternatively, a fast cure process at 126°C (260°F) for 1 hour, without damage. In the final step, the two carbon air duct halves were assembled and secured together.
	Finishing and Results The team tested the same mold for 6 cycles without significant degradation and estimated that one mold could be used for approximately 10–15 cycles. Because the prepreg process uses an autoclave for heat and pressure during curing, 3D printed molds can only withstand a limited number of uses. Therefore, this method is not suitable for high-volume production but is an excellent approach for short-run batches and mass customization. This approach opens up various applications, such as: High-performance sports equipment Specialized tools for the aerospace industry Custom prosthetics or artificial limbs for patients in the medical field

3D Printing with Carbon Fiber

There is a strong demand for workflows that combine the strength, durability, and robustness of traditional carbon fiber parts with the flexibility, ability to create complex shapes, and repeatability of 3D printing.

It is therefore not surprising that many 3D printing companies offer carbon fiber 3D printing solutions. Currently, there are two main processes: printing with chopped carbon fibers and with continuous fibers.

Using chopped carbon fibers, Nylon 11 CF Powder for industrial Selective Laser Sintering (SLS) 3D printers like the Fuse 1+ 30W allows manufacturers to create strong, lightweight, and heat-resistant parts without relying on traditional layering or machining methods.

Formlabs Nylon 11 CF Powder offers strength, light weight, and heat resistance, making it ideal for applications in the automotive, aerospace, and industrial manufacturing industries.

Getting Started with Carbon Fiber Production

Producing fiber-reinforced polymers is an exciting but complex and labor-intensive process.

Using 3D printed molds and prototypes for carbon fiber part manufacturing helps businesses simplify workflows, increase design flexibility and opportunities, and reduce costs and production time.

For directly 3D printed parts, which offer many advantages of carbon fiber along with the added benefits of geometric flexibility and a simpler, more efficient process, there's Formlabs Nylon 11 CF Powder for the Fuse Series SLS 3D printers.

If you'd like to discuss your application and find the most suitable approach for using 3D printing for carbon fiber part manufacturing, please contact our team.

	Formlabs Form 4 SLA printer details click here    Check prices click here
	Formlabs Fuse 1+ 30W SLS printer details click here    Check prices click here

References

https://formlabs.com/global/blog/composite-materials-carbon-fiber-layup/