Forged Carbon Fiber vs Chopped Carbon Fiber | What's The Difference?

In the world of advanced materials, carbon fiber stands out for its incredible strength-to-weight ratio, making it a favorite in industries ranging from aerospace to automotive and sporting goods. This of course, includes Harley Davidson. Who has introduced carbon fiber onto new bike models. However, not all carbon fiber is created equal. Two prominent manufacturing techniques, forged carbon fiber and more traditional carbon fiber, offer distinct properties and advantages. This post will delve into the differences between these methods, highlighting their unique characteristics and applications.

Traditional Carbon Fiber Manufacturing (Similar To How All Of Our Carbon Fiber Parts are made) Light Resin Transfer Molding (LRTM)

The Process

Traditional carbon fiber manufacturing involves several meticulous steps:

1. Mold Preparation: The process begins with the preparation of the mold. The mold is typically made of two parts: a rigid lower mold (often referred to as the "tool") and a semi-flexible upper mold (the "counter-mold"). Both parts are designed to fit together perfectly to form a sealed cavity.
2. Fiber Placement: Dry fiber reinforcements, such as carbon fiber, is carefully placed into the lower mold. These fibers provide the structural strength of the final composite part.
3. Mold Closure: The upper mold is placed over the lower mold, and the two parts are clamped together to create a sealed cavity. The mold is then prepared for resin injection.
4. Resin Injection: Resin is injected into the mold cavity under controlled pressure. The resin flows through the fiber reinforcements, fully impregnating them to form a solid composite structure. In LRTM, the resin is injected at relatively low pressures, reducing the risk of fiber displacement and ensuring a consistent resin distribution.
5. Curing: Once the resin has been injected, the mold is typically heated to accelerate the curing process. The resin hardens, bonding with the fibers to create a strong, lightweight composite part.
6. Demolding: After curing, the mold is opened, and the finished part is removed. The part may undergo additional finishing processes, such as trimming and sanding, to achieve the desired final appearance.

Characteristics

• Strength and Stiffness: Traditional carbon fiber components are renowned for their high tensile strength and stiffness.
• Customization: The weaving process allows for customization of fiber orientation, enhancing specific strength and stiffness characteristics.
• Surface Finish: The finished products often have a smooth, woven texture, which is visually appealing.
  
  That being said, our process slightly varies but runs parallel to other Resin Transfer Molding techniques. Even with our Chopped Carbon fiber products, the process remains the same.

Forged Carbon Fiber Manufacturing

The Process

Forged carbon fiber employs a different approach:

1. Chopping: Continuous carbon fibers are chopped into short, random lengths.
2. Mixing: These chopped fibers are mixed with resin to create a paste-like material.
3. Compression Molding: The mixture is placed into a mold and subjected to high pressure and temperature, compressing the fibers into a dense, solid form.

Characteristics

• Complex Shapes: The molding process allows for the creation of complex, intricate shapes that are difficult to achieve with traditional carbon fiber.
• Surface Finish: The appearance of forged carbon fiber is typically more random and less uniform, with a distinctive mottled texture.
• Easily Repeatable: Being an absolute repeatable process, manufacturers utilize this process as it is a more time-cautious, higher volume process, thus, allowing them to mass produce these carbon fiber parts.

Physical Differences

Strength and Stiffness

• Traditional Carbon Fiber: Exhibits higher tensile strength and stiffness along the direction of the fibers, making it ideal for applications requiring maximum strength in specific directions, such as aircraft wings and high-performance motorcycles.
• Forged Carbon Fiber: Offers more balanced strength in all directions, making it suitable for components that experience multi-directional stresses, such as sporting equipment and protective gear.

Weight

Both materials are lightweight, but the specific weight can vary depending on the resin content and the fiber-to-resin ratio used in the manufacturing process. Traditional carbon fiber often has a higher fiber content, making it slightly lighter for the same volume. Whereas forged carbon goes through a compression process, making it denser, ultimately making it a bit higher in weight compared to more traditional manufacturing methods. 

Conclusion

Both forged carbon fiber and traditional carbon fiber have unique advantages that cater to different applications. Understanding the differences in their manufacturing processes and physical properties can help you choose the right product for your specific needs. At Hofmann Designs, we have been manufacturing chopped carbon fiber products since 2020. In fact, we've done multiple bikes fully equipped with this chopped carbon fiber, like shown on this 2021 Road Glide. 



That being said, to match the forged carbon fiber parts that Harley Davidson is producing, we have introduced a matte sheen into our process which matches the factory forged carbon parts. Allowing you to match our aftermarket carbon fiber parts, to your factory parts. We still offer everything in a high gloss finish, as shown on the 2021 Road Glide, but now we have both options to suit your style.

Examples of our Chopped Carbon Fiber 


If you're interested in these chopped carbon fiber parts, contact us!