Both hobbyists and professionals find carbon fiber rods to be useful building blocks for any number of structures. Because carbon fiber is so rigid, carbon fiber rods are an excellent choice for any application where stiffness and lightness are important. Carbon fiber rods are sometimes used to replace steel rods, but they more often replace aluminum. Carbon fiber rods can be as little as ⅓ the weight of a comparable aluminum rod with similar or better strength characteristics.
How Carbon Fiber Rods Are Made
Carbon fiber rods are manufactured by pulling continuous carbon fibers mixed with epoxy resin through heated forming dies, a process known as pultrusion. Pultrusion is similar to the extrusion process used with aluminum and thermoplastic. Through this process, continuous lengths of carbon fiber rods with constant cross-sections can be created, and they take on the shape of the die. As the carbon fibers are pulled through the die and saturated with epoxy resin, the heat from the die begins the resin-hardening, or polymerization, process.
Advantages to using pultrusion to create carbon fiber rods include:
High axial strength and stiffness
Straight and parallel fiber alignment
Tightly controlled cross section dimensions
The extrusion process produces straight, rigid, lightweight rods with a low coefficient of thermal expansion. As with all carbon fiber products, carbon fiber rods have a high stiffness-to-weight ratio. They also boast exceptional linear strength because most of the carbon fibers run along the length of the rod on the 0° axis. The extrusion process also allows for a tight outer diameter (OD) tolerance.
Uses for Carbon Fiber Rods
The high stiffness-to-weight ratio of carbon fiber rods makes them an excellent choice for creating lightweight frame constructions. They are therefore often found in structural space frames and trusses. Many remote control (RC) enthusiasts find carbon fiber rods to be the perfect material from which to construct their models. Carbon fiber rods are an excellent material for building engineered and high-performance structures, particularly when combined with carbon fiber laminates. Generally speaking, carbon fiber rods perform particularly well in bending and axial tension or compression applications.
It is important to know that the fiber orientation of carbon fiber rods means that they do not hold up well under high torque or transverse crushing loads. They can shatter in these loading conditions, making them a poor choice for applications that require resistance to torsional or side loads.
Working with Carbon Fiber Rods
Carbon fiber rods are relatively easy to work with. As with any building project, having the right tools on hand makes the job that much safer and simpler. However, there are many tools that can be used to work with carbon fiber rods. A good quality fine-toothed band saw, coping saw, scroll saw, end mill or Dremel tool will make quick work of cutting carbon fiber rods to the exact length needed for your project. Since they are pultruded in an epoxy matrix, they can be easily bonded together easily using epoxy resin.
Due to their rigidity, light weight, and strength, carbon fiber rods are often used to frame projects when stiffness and weight count. The extrusion process used to manufacture carbon fiber rods offers significant advantages for applications where precision counts. The pultrusion process aligns the carbon fibers perfectly while also offering the ability to create perfectly-shaped, smooth rods with tight OD tolerances that can be cut to any length. The tools needed to cut and bond carbon fiber rods are readily available in the garages of most enthusiasts and handymen. It is no wonder, then, that carbon fiber rods are often the preferred choice for both hobbyists and professionals alike.