Carbon Fiber Composite Design Guide

The purpose of this design guide is to provide general information and specifications on graphite (carbon fiber) composite materials and some guidelines for designing lightweight high performance products with graphite composites. If you have more specific questions, please contact our engineers at Performance Composites, and they will gladly assist you.

Graphite composites have exceptional mechanical properties which are unequalled by other materials. The material is strong, stiff, and lightweight. Graphite composite is the material of choice for applications where lightweight & superior performance is paramount, such as components for spacecrafts, fighter aircrafts, and race cars.

Composite materials are made by combining reinforcement (fiber) with matrix (resin), and this combination of the fiber and matrix provide characteristics superior to either of the materials alone. In a composite material, the fiber carry majority of the load, and is the major contributor in the material properties. The resin helps to transfer load between fibers, prevents the fibers from buckling, and binds the materials together.
Graphite fibers (sometimes called carbon fibers) are made from organic polymer such as polyacrylonitrile. The material is drawn into fibers and kept under tension while it is heated under high temperature (> 1000C). 2 dimensional carbon-carbon crystals (graphite) are formed when the hydrogen is driven out. The carbon-carbon chain has extremely strong molecular bonds (diamond is a 3 dimensional carbon-carbon crystal), and that is what gives the fibers its superior mechanical properties.

Historically, graphite composites have been very expensive, which limited its use to only special applications. However, over the past fifteen years, as the volume of graphite fiber consumption has increased and the manufacturing processes have improved, the price of graphite composites has steadily declined. Today graphite composites are economically viable in many applications such as sporting goods, performance boats, performance vehicles, and high performance industrial machinery.

Applications of Graphite Composite Materials
Composite materials are extremely versatile. The engineer can choose from a wide variety of fibers and resins to obtain the desired material properties. Also the material thickness and fiber orientations can be optimized for each application.

The advantages of graphite composites are:
1. High specific stiffness (stiffness divided by density)
2. High specific strength (strength divided by density)
3. Extremely low coefficient of thermal expansion (CTE)
4. X-ray transparent (due to its low molecular weight)

Please see table 1 for a comparison of costs and mechanical properties of graphite composite, fiberglass composite, aluminum, and steel. Due to the wide variety of graphite fibers and resins available, and the numerous combinations of the materials, the properties are listed in ranges.



Graphite Composite (aerospace grade)

Graphite Composite (commercial grade)

Fiberglass Composite

Aluminum 6061 T-6



Cost $/LB






Strength (psi)






Stiffness (psi)

10 x 106 - 50 x 106

8 x 106 - 10 x 106

1 x 106 - 1.5 x 106

10 x 106

30 x 106

Density (lb/in3)






Specific Strength

1.8 x 106 - 4 x 106

1 x 106 - 1.8 x 106




Specific Stiffness

200 x 106-1,000 x 106

160 x 106-200 x 106

18 x 106-27 x 106

100 x 106

100 x 106

CTE (in/in-F)

-1 x 10-6 – 1 x 10-6

1 x 10-6 – 2 x 10-6

6 x 10-6 – 8 x 10-6

13 x 10-6

7 x 10-6


Applications for High Specific Stiffness

Graphite composites are ideally suited for applications where high stiffness and low weight is required. Most metals used for structural applications have very similar specific stiffness, which is around 100 x 10^6 psi. If an application demands high stiffness and lightweight, graphite composites are the only material of choice.

Examples are:

  • Spacecraft structure
  • Aircraft structure
  • Drive shaft for trucks and high performance vehicles
  • Machinery rollers
  • Sail boat mast and boom
  • Bicycle frame
  • Machinery components that experience high acceleration & require stiffness & precision

Applications for High Specific Strengths

Graphite composites are widely used for lightweight structures that need to carry extremely high loads.

Examples are:

  • Motorcycle components (skid plates, rock guards)
  • Fishing pole
  • Golf club shaft
  • Aircraft structure
  • Satellite antenna structures
  • Racecar chassis

Applications for Low CTE

Graphite fiber has a negative coefficient of thermal expansion, which means when it is heated it will shrink. When the graphite fibers are put into a resin matrix (positive CTE), the composite can be tailored to have almost zero CTE. Graphite composites are used for high precision and thermally stable applications.

Examples are:

  • High precision antennas
  • Scanning & imaging machines
  • Precision optical devices
  • Metrology equipment

Manufacturing Process

Graphite composite components are manufactured utilizing a molding process. The graphite fibers can be woven into cloth, braided into tubes, or made into unidirectional tapes. The fibers are next coated with resin. This fiber & resin mix can be partially cured then frozen to create a pre-preg, or the fiber & resin mix can be used wet. The graphite fiber & resin mix is then placed into a mold in layers. The number of layers and the orientation of the layers will depend on the mechanical properties desired. The layers of graphite is then compacted and consolidated in the mold by pressure from a press or from a vacuum bag. Depending on the resin system, the part can be cured at room temperature or elevated temperature. Once the part is cured, the part is removed from the mold, and it is ready for finishing operations such as trimming and drilling.

Design Information

Graphite composites are considered designer's material, because the parts can be tailored to have strength and or stiffness in the directions and locations that are necessary by strategically placing materials and orienting fiber direction. Also the design and manufacturing flexibility that graphite composites offers provide opportunities to consolidate parts and to incorporate many features into the part to further reduce the total part price. Some general design guidelines are listed below:

Material Thickness

Typically range from .040” to ½”.  Can use sandwich construction to achieve lighter and stiffer parts.

Corner Radius

Recommend 1/8” or larger


Will duplicate the shape of the mold.  Can be heavily contoured.

Dimensional Tolerance


Surface Finish

Tool side can be class A

Can be gel coated painted, or use any other surface coating


.0005 in/in

Electrical Properties

Electrical conductive

Fire Retarding

Resins available in fire retardant applications meeting various ASTM classes & smoke generation requirements


Resins available for corrosion applications, especially for hot brine, most acids, caustics, & chlorine gases



Molds are used to define the shape of the composite parts. The graphite composite part will pick up all shapes and features of the molds; therefore the quality of the part is heavily influenced by the quality of the mold. The molds can be either male or female. The female molds are the most common and they will produce a part with a smooth exterior surface while a male mold will produce a smooth interior surface. A matched mold (male and female) is required if the part is consolidated using a press. The molds can be made with composite materials, metal filled epoxy, or machined from aluminum or steel. The type of mold and materials used depends on the type of part and the production quantity.


Go back


Why Performance Composites?

  • Quality
  • High Quality Composite Manufacturing ISO 9001: 2015 certified
  • Receive composite parts that will consistently meet your specifications every time. We use high-quality molds, well-designed manufacturing processes, optimal composites materials, effective ISO 9001:2015 quality processes, and well-trained employees to consistently achieve 100% quality ratings from our customers.
  • Rely on us to supply all of your critical fiberglass composites. We are honored to be designated as a strategic supplier by many of our large OEM customers, and we have many customer partners for over 10 years.
  • Cost-Effective
  • Cost Effective Solutions Using Fiberglass and Composite Materials
  • Receive low cost, high performance composites and fiberglass parts that are value engineered and are manufactured using the most cost-effective materials and processes.
  • Reduce your overall part cost and improve product performance when we help you convert your existing designs from sheet metal or plastics to composites.
  • Save time and money by utilizing our efficient workforce and low overhead to perform your custom assembly.
  • Reliable
  • Reliable On-Time Delivery of Your Composite Parts
  • Receive your composite products on time! Our production team is dedicated to on-time delivery, and we consistently achieve 100% on-time delivery ratings from our customers.
  • Receive the fastest response time from the composite industry. Our typical production through-put time is less than 2 weeks.
  • Have your fiberglass composites products delivered on a "Just-in-Time" basis to help you minimize your inventory.
  • Rely on us to work with your Kan Ban system to simplify your order fulfillment and ensure your composite parts are always available.
  • Service
  • Superior Customer Service from our team
  • Receive excellent customer service. Performance Composites is structured as a service company that specializes in composite fabrication. We are committed to serving our customers and developing long-term mutually beneficial partnerships. Many of our customers have been partners with us for over 10 years.
  • Receive support from our experienced team on every step of the process from design, engineering, process development, project management, prototype development, composite product manufacturing, quality control per ISO 9001:2015, custom assembly, packaging and shipping. We will help you optimize performance, quality and cost.

Company Information

Performance Composites is a full service composites manufacturer providing engineered fiberglass products to original equipment manufacturer (OEM). We offer engineering, analysis, design assistance, process development, tooling fabrication, composite fabrication, assembly, quality control and project management. Our goal is to provide high-quality fiberglass manufacturing, cost-effective solutions, superior service and on-time delivery.

Contact Information

  This email address is being protected from spambots. You need JavaScript enabled to view it.
  This email address is being protected from spambots. You need JavaScript enabled to view it.
  This email address is being protected from spambots. You need JavaScript enabled to view it.
  +1 (310) 328-6661
  +1 (310) 782-3578
  1418 Alameda St Compton, CA 90221
  4902 Ampere Dr. Reno, NV 89502

Get Map (California)
      Get Map (Nevada)