Carbon Fiber Composites: Processing Guide

Welcome to IDEAL's ultimate guide to Carbon Fiber Composites: Processing Guide

Our blog is a comprehensive resource for anyone interested in learning more about this versatile and affordable option.

What is Carbon Fiber?

Carbon fiber is composed of strands of fibers 5 to 10 microns in diameter that consist of long, tightly interlocked chains of carbon atoms in a microscopic crystalline structure.

These fibers are extremely stiff, strong, and light, and are used in many processes to create high-performance building materials. Carbon fiber reinforcements come in a variety of weaves, braids, and other formats such as tow, and uni-directional.

These are combined with various resins to produce carbon fiber-reinforced composites in a wide range of shapes and fiber patterns.

Key Characteristics of Carbon Fiber

High Strength-to-Weight Ratio – Stronger than steel but significantly lighter, ideal for weight-sensitive applications.

High Stiffness – Excellent rigidity, maintains shape under stress.

Low Density – Very lightweight (~1.6 g/cm³).

Corrosion Resistance – Does not rust or corrode, even in harsh environments.

Fatigue Resistance – Retains performance under repeated stress cycles.

Low Thermal Expansion – Dimensionally stable under temperature changes.

Electrical Conductivity – Conductive, unlike most polymers.

Design Flexibility – Can be molded into complex shapes and structures.

Aesthetic Appeal – Distinctive woven pattern, often left exposed in design.

Cost – Relatively high compared to metals and fiberglass, due to production complexity.

Material Forms

Carbon Fibers: Continuous or chopped strands, can be woven into fabrics.

Resins (Matrix): Epoxy, vinyl ester, polyester.

Prepregs: Fibers pre-impregnated with resin for consistent quality.

Carbon Fiber Manufacturing in 6 Steps

In the carbon fiber production process, the raw materials, called precursors, are drawn into long strands of fibres. The fibres are then woven into a fabric. They can also be combined with other materials that are filament wound or molded into desired shapes and sizes.

The manufacturing process is as follows:

Raw Material (Precursor) – Start with PAN, pitch, or rayon.

Spinning – Spin into long, fine fibers.

Stabilization – Heat in air (200–300°C) to strengthen structure.

Carbonization – Heat in inert gas (1,000–3,000°C) → pure carbon chains.

Surface Treatment & Sizing – Improve bonding with resins and add protection.

Weaving & Shaping – Woven into fabrics or molded into prepreg sheets → cured into strong, lightweight parts.

Key Considerations in Carbon Fiber Machining

Cost & Repair Challenges

Recovery and repair processes are complex and expensive compared to metals or other composites.

Surface Treatment Sensitivity

Surface finishing must be carefully controlled—over-treatment can cause pits or defects that compromise fiber strength.

Quality Control

Precise process monitoring is essential to maintain uniform fiber quality and mechanical properties.

Electrical Conductivity Risks

Carbon fibers are highly conductive, which may cause arcing or shorts in nearby electrical equipment if not managed properly.

Health & Safety

Fine dust and fiber particles can irritate the skin, eyes, and respiratory system, requiring proper PPE and dust extraction systems.

Comparison of Carbon Fiber Composite, Fiberglass Composite, Aluminum and Steel

Here’s a detailed comparison of costs and mechanical properties for carbon fiber composites, fiberglass composites, aluminum, and steel. I’ll break it down by material and then provide a comparative table for clarity.

Why Carbon Fiber Is Chosen?

Reason 1: Strength

The primary reason why one would consider the use of carbon fiber is its high stiffness to weight ratio. Carbon fiber is very strong, very stiff, and relatively light.

The stiffness of a material is measured by its modulus of elasticity. The modulus of carbon fiber is typically 34 MSI (234 Gpa). The ultimate tensile strength of Carbon Fiber is typically 600-700 KSI (4-4.8 Gpa). Compare this with 2024-T3 Aluminum, which has a modulus of only 10 MSI and ultimate tensile strength of 65 KSI, or with 4130 Steel, which has a modulus of 30 MSI and ultimate tensile strength of 125 KSI.

Reason 2: Low Thermal Expansion

One important benefit of choosing carbon fiber is its dimensional stability with changes in temperature. Carbon fiber has a coefficient of thermal expansion of less than one-millionth of an inch per degree F, vs 7 millionths of an inch/inch per degree F for steel, or 13 millionths in/in for aluminum.

Reason 3: Anisotropic Properties

When designing composite parts, one cannot simply compare the properties of carbon fiber versus steel, aluminum, or plastic. These materials have homogeneous (properties are the same at all points), and isotropic (properties are the same along all axes).

By comparison, carbon fiber parts are neither homogeneous nor isotropic. In a carbon fiber part, the strength resides along the axis of the fibers, and thus fiber density and orientation greatly impact mechanical properties. This provides the ability to tailor the mechanical properties of a part along any axis.

Carbon Fiber Prototyping

An integral part of the design process is prototyping. At IDEAL, our carbon fiber prototype group is staffed by experienced engineers and seasoned craftsmen. Carbon fiber prototyping can range from simple test pieces to fully functional near production-ready assemblies.

Often individual components and sub-assemblies go through extensive testing to validate design calculations and assure the customer that the final product will meet all specifications.

In addition to their use in evaluating functionality, our high-quality carbon fiber prototypes are often by customers as marketing tools. Our prototype team aims for production-level quality, in both form and function, even at the early stages of product development.

Conclusion

Carbon Fiber Machining is revolutionizing manufacturing by enabling faster prototyping, reducing costs, and offering a new level of design freedom. It’s widely used in various industries, from consumer products to aerospace, and its potential is still growing. Would you like to know about any Carbon Fiber Machining technology or material?

Contact IDEAL whenever you need help assessing the manufacturability of your product designs.