There are several ways to categorize the different carbon fiber fabrics that exist.

In this article, we’ll explore the different types of carbon fiber and the properties that set them apart. When we refer to carbon fiber, we often mean a carbon-fiber composite—fiber combined with resin and cured. However, covering every possible composite configuration would make this article far too long, so we will focus exclusively on the types of raw carbon fiber, without considering resin systems.

Classification by Precursor Material

One of the most common ways to categorize carbon fibers is by the precursor from which they are produced. Today, two main precursor families dominate the industry.

Polyacrylonitrile (PAN)

PAN is the dominant precursor, accounting for roughly 90% of commercial carbon fibers. It is valued for its high carbon yield and excellent mechanical performance, which have made it the industry standard. PAN can be used as a homopolymer or a copolymer, often with additives that enhance processing and improve final fiber properties.

Pitch

Pitch-based carbon fibers are produced from petroleum- or coal-derived asphalt. They are mainly used when extremely high performance is required, as this precursor allows the production of fibers with very high modulus and exceptional thermal stability. While less common than PAN-based fibers, pitch-derived fibers excel in applications demanding the highest stiffness levels.

Rayon

Rayon was the first precursor used to produce carbon fibers in the 1950s and 1960s. It originates from a cellulosic source, typically dissolving pulp. Although it has largely been replaced due to its lower carbon yield and higher cost, it remains historically significant as the origin of carbon-fiber technology.

It’s not only about aesthetics, every type of carbon fiber fabric has specific mechanical characteristics. Credit: Christine Twigg

Classification by Mechanical Properties

The two primary mechanical properties used to distinguish one carbon fiber from another are tensile strength and tensile modulus. Tensile strength is the maximum force a material can withstand while being pulled or stretched before breaking or becoming permanently deformed.Tensile modulus measures a material’s stiffness—its resistance to stretching or deforming under tension.

These metrics are essential for achieving the desired mechanical performance and can vary widely between fiber types. A common classification system groups fibers according to their elastic modulus, resulting in five categories.

Low Elastic Modulus

• Tensile modulus ≤ 200 GPa
• Tensile strength ≤ 3500 MPa

Standard Elastic Modulus

• Tensile modulus: 200–275 GPa
• Tensile strength: 2500–5000 MPa

Intermediate Elastic Modulus

• Tensile modulus: 275–350 GPa
• Tensile strength: 3500–8000 MPa

High Elastic Modulus

• Tensile modulus: 350–600 GPa
• Tensile strength: 2500–5000 MPa

Ultra-High Elastic Modulus

• Tensile modulus: 600–950 GPa
• Tensile strength: 2500–4000 MPa

Classification by Form

Another essential factor when choosing a carbon fiber is its form, since this determines how it can be used. Because carbon fiber is anisotropic, the orientation of its filaments greatly influences the material’s mechanical behavior.

Unidirectional Tape

An arrangement of continuous fibers aligned in the same direction. This provides extremely high tensile strength along that orientation and allows engineers to tailor mechanical performance based on fiber direction and the number of layers used.

Fabric Forms

Carbon-fiber fabrics are created by interlacing fibers, just like any textile. Different weave patterns result in different properties. These are the three most common types:

Plain Weave

Plain weave interlaces fibers in an alternating over-under sequence, forming a simple checkerboard-like pattern. It offers balanced strength in multiple directions, excellent dimensional stability, and easy handling—ideal for flat or gently curved surfaces. However, it is not the best option for highly complex geometries.

Twill Weave

Twill weave typically appears in 2×2 or 4×4 patterns. In a 2×2 twill, each tow passes over two and under two; a 4×4 follows the same principle with four. This produces the fabric’s characteristic diagonal pattern. Twill is more pliable and drapes better over complex shapes while maintaining good stability, though it requires more careful handling to avoid distortion.

Satin Weave

Satin weaves provide excellent drapability and easily conform to complex contours, though they are less stable than plain or twill weaves. Common variants include 4HS, 5HS, and 8HS, where the tow passes over several tows and under one (3/1, 4/1, and 7/1 respectively). Higher harness numbers improve drape but reduce stability.

Chopped Fiber

With the increasing popularity of forged carbon fiber, another available format is chopped fibers or short strands. This material adapts easily to complex molds, though forged carbon exhibits mechanical behaviors different from traditional continuous-fiber composites. If you want to learn more about the strengths and applications of forged carbon fiber, we recommend this article where we analyze its unique advantages.

Forged carbon fiber partial cover for a Lamborghini engine bay.

Classification by Tow Size

Carbon-fiber filaments are extremely small—typically 5–9 microns in diameter. Before weaving, they are grouped into bundles called tows. A common way to describe fabric weight or thickness is by specifying the number of filaments per tow.

A 3K fabric is made with tows of 3,000 filaments per tow. A 6K fabric is composed by tows with 6,000 filaments per tow, and a 12K fabric contains tows made by 12,000 filaments each. Tow size directly influences fabric appearance, weight, and handling characteristics.

TL;DR

Carbon fibers come in many types, defined mainly by their precursor (PAN, pitch, or rayon), their mechanical performance (from low to ultra-high modulus), their form (unidirectional tape or woven fabrics like plain, twill, and satin), and their tow size (3K, 6K, 12K, etc.). PAN is the standard precursor, pitch is used for the highest-stiffness fibers, and rayon is historically significant. Fabric weave and tow size determine drape, stability, and final part behavior, while chopped fiber enables forged-carbon applications.

The post Carbon Fiber Types appeared first on Managing Composites.

Madrid, 28^th of April 2022 – Managing Composites, the engineering company specialized in composite materials projects, today announced the close of a 1,5M€ financing round by Bouwen Sistemas Industriales, holding of Itera Mobility Engineering, Hidragrup and Sinfiny.

The investment will enable Managing Composites to continue providing best in class engineering composite services while facing bigger challenges, boosting the lightweighting transformation of traditional industries, as well as, opening new markets. The company is already providing services to world-class hypercar and automotive brands, electric airplanes, space applications, underwater robots and sports material. In addition, the investment will allow the company to keep on transforming some of the services and R&D activities into products. Managing Composites projects portfolio already have The Native Lab, a composites EdTech company and two R&D projects close to be commercialized (SaaS for automatic defect analysis and a revolutionary reusable and full recyclable resin) as own initiatives.

“We are thrilled by Bouwen’s support, who sees the composites growing market as a one of the future key technology drivers in all the new mobility scheme” said Lluc Marti, founder and Managing Composites CEO. “The need of experts in composites has never been greater, especially with the need of lightweighting in new transportation solutions. This is the time for Managing Composites to continue growing and realize our vision of spreading composites word while making it more sustainable, affordable, and technically accessible.”

The use of composites and its knowhow, especially outside the aerospace world, has been developed privately in workshops/factories in a learning by doing process. For that reason, the companies that have the know-how are hesitant to share it. Managing Composites’ founding team has been involved throughout the complete value chain and understands that sharing the knowledge is key to help developing the industry.

The Managing Composites adventure started at the end of 2019 and since then has grown with pure bootstrapping, achieving 1,3M€ of turnover in 2021. The company plans to exceed 2,2M€ in 2022.

Bouwen Sistemas Industriales, is a holding of industrial companies. They have a well stablished engineering company in the automotive and railway industry, Itera Mobility Engineering, a hydraulic presses and industrial equipment manufacturer, Hidragrup, and one company specialized in the automatization of industrial processes, Sinfiny Smart Solutions. This way, Bouwen covers the whole value chain, starting with the conceptualization and development of products, going through the construction of machinery, the design, automatization, and set-up of processes and ending with on-site engineering support during serial life.

Bouwen started its journey back in 2003 and since then, the company has kept on growing, both organically and inorganically, incorporating companies that complemented their capabilities. Bouwen targets 20M€ sales for 2022 and 200 employees, that includes the extension of the operations to North America.

What started as a collaboration project between Managing Composites and Itera Mobility Engineering, ended one year later with Bouwen (Itera’s owner) becoming a shareholder in Managing Composites, trusting on the current management team, and understanding what can be delivered with further resources.

 “For Bouwen has been a strategic investment. Given the increasing need of the main OEMs in keep on reducing weight, especially for the electrical vehicles and our aim on always offering innovative solutions, we consider the incorporation of Managing Composites into our group can be a perfect complement to the services we are providing to our current and future customers. Being together will allow synergies among the different companies in our portfolio and facilitating making available composites technologies developed in niche sectors, today ready to be implemented in big OEMs and TIERs” says Héctor Corral, Bouwen CEO.

 “We were not looking for investment. Nevertheless, after some months of project meetings, possible synergies with other companies from the holding, both sides realised that it will be a win-win situation. We will have the capacity to grow faster with the unevaluable experience from Bouwen who grew from scratch an engineering company to become a market reference. And for Bouwen, we are opening doors to a new engineering and industrial fast-moving market” says Alex Batán, CPO at Managing Composites.

The post Managing Composites closes 1,5M€ funding round by Bouwen, to accelerate growth appeared first on Managing Composites.

Why make them so thin?

In short, carbon fibers are manufactured through the stabilization, carbonization and graphitization of a precursor (generally polyacrylonitrile or petroleum pitch). The crystal structure of graphite consists of sp2 hybridized carbon atoms arranged two-dimensionally in a honeycomb structure in the x-y plane. The layers, termed graphene layers, are stacked parallel to each other in a 3D structure.

A precursor with a smaller fiber diameter allows for a higher graphitization degree. In other words, the carbon fiber will have greater graphite content. This way, the probability of having a concentration of defects in the 3D structure is considerably reduced. That is why the mechanical properties of fibers are inversely proportional to their filament diameter.

The post Why are carbon fibers so thin? appeared first on Managing Composites.

These problems would only be solved in 1932 by Dale Kleist, a graduate student who was working part-time at Owens-Illinois as a researcher. The company wanted to make glass blocks for architectural use, and its researchers were looking for a way to seal the two halves of a block together so that moisture couldn’t get inside.

He decided to try a metal-spraying gun with molten glass instead of bronze and discovered that it created a shower of ultrafine, thread-like glass fibers.

Owens-Illinois immediately recognized that this was an excellent way to make glass wool for insulation and that it might be adaptable for other applications.

Four years and the researchers were turning out individual strands long and flexible enough to be woven into cloth. The cloth was remarkably strong, and it could be cut and folded just like ordinary fabrics.

Bibliographical Reference:

The Fiberglass Story, written by Michael Lamm

The post The history of fiberglass appeared first on Managing Composites.