Properties and Uses of CarboSix Carbon Fiber Profiles

Introducing CarboSix

The basis of CarboSix profiles is carbon fiber. Carbon fiber is composed of carbon atoms bonded together to form a long chain. The fibers are extremely stiff, strong, and light and are used in many processes to create excellent building materials.

As you can tell from the image above, our CarboSix modular carbon fiber profiles can be shaped and cut in much the same way our extruded aluminum T-slot profiles are. True, you can use CarboSix much like aluminum, and it has the same structural modularity. And from cutting to perforation, it can undergo the same processing. It even uses the same kind of accessories as aluminum, with identical installation and fastening systems.

But that doesn’t mean aluminum and carbon fiber profiles are perfectly interchangeable. CarboSix is really best reserved for certain applications unsuitable for aluminum or steel, and that take advantage of the unique, specific properties of carbon fiber. Here are the most notable applications for CarboSix:

  • Automation and robotics (e.g., grippers and other attachment tools—see our previous blog article on the benefits of using carbon fiber to build robots)
  • High-performance structures
  • Wherever very low bending is required (e.g., test benches)
  • Wherever structural lightness is required
  • Metrology (requiring zero thermal expansion as well as low bending)
  • General applications, such as packaging and special machinery
  • Handling and transport (e.g., roller conveyors)

Versatile Carbon

Consider two very different objects: a diamond ring and a common lead pencil. What do they have in common? At first blush, nothing. A diamond is the hardest known naturally occurring substance; whereas the graphite in the pencil is one of the softest. And yet, as any chemist will tell you, both are made entirely from the exact same element: carbon. The only difference is how the individual atoms are arranged and bond together in these two allotropes (structurally different forms) of carbon.

As the drawings below illustrate, the reason a diamond is so hard is that each carbon atom is covalently bonded to four other atoms in a tetrahedron shape, forming an extremely sturdy three-dimensional crystal network. On the other hand, the carbon atoms in graphite are arranged in loosely layered sheets, such that when you write with a pencil, these sheets are shed onto the paper, leaving behind visible pencil marks.

Molecular structure of diamond and graphite
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ only in structure (source).

One element with two very different sets of appearance, properties, and uses: that is what makes carbon such a versatile industrial material for the 21st century. For industries today, one of the most exciting of these allotropes is carbon fiber.

What’s Old Is New

Carbon fiber has been touted as the next great innovation that will allow humans to build amazing structures once unimaginable.

Yet do not make the mistake of thinking that carbon fiber is a 21st-century invention. In fact, it dates back to before the American Civil War, when English physicist, chemist, and inventor Joseph Swan first began working on a light bulb using carbonized paper filaments in an evacuated glass bulb. Later, in 1879, Thomas Edison baked cotton threads and bamboo slivers at high temperatures, carbonizing them into an all-carbon fiber filament used in one of the first incandescent light bulbs (carbon fiber, like graphite, is a good conductor of electricity, whereas diamonds are not).

This material did not have the tensile strength of today’s carbon fibers, but it allowed Edison and Swan to replace the expensive platinum filaments being used earlier. The bamboo–carbon filaments Edison developed lasted up to 1,200 hours, and they were the norm for 10 years, until tungsten filaments replaced them.

Carbon fiber compared to human hair
A 6 μm diameter carbon filament compared to a human hair (source)

Nowadays, carbon filament is produced from a polymer such as polyacrylonitrile (PAN), rayon, or petroleum pitch. For synthetic polymers such as PAN or rayon, the precursor is first spun into filament yarns, using chemical and mechanical processes to initially align the polymer molecules in a way to enhance the final physical properties of the completed carbon fiber. The polymer filament yarns are then heated to drive off non-carbon atoms, producing the final carbon fiber.

The carbon fiber filament is thinner than a human hair.

How CarboSix Profiles Are Made

Unlike our aluminum profiles, which are extruded (i.e., manufactured by pushing a heated and softened aluminum bar through a die that molds it into the desired shape), CarboSix profiles are made through the process of “pultrusion,” in which carbon fibers are pulled through an epoxy resin bath and then through a die (at a controlled temperature) where the polymerization and shaping of the composite material take place.

CarboSix pultrusion manufacturing station
Pultrusion manufacturing station (click to enlarge).

The Advantages of CarboSix

The stiffness of a material is measured by its “modulus of elasticity.” The modulus of carbon fiber is typically 33 MSI, and its ultimate tensile strength is typically 500 ksi. This is over twice the stiffness of steel yet still only half the weight of aluminum.

CarboSix carbon fiber composite profile
CarboSix profile: the stiffness-to-weight ratio of this material is over ten times that of either steel or aluminum.

The properties of a carbon fiber part are close to that of steel, and the weight is less than that of aluminum, and close to that of plastic. Thus, the strength-to-weight ratio as well as stiffness-to-weight ratio of a carbon fiber part is much higher than either steel or plastic. Other advantages include:

  • From 70% to 50% weight saving
  • Stiffer structures with unaltered or lighter weight
  • Much smaller sections with equal rigidity and mechanical strength
  • Null thermal expansion and high rigidity
  • Increase in payload (equal equipment, robots, engines, etc.) and operational speed
  • Reduction in wear & tear on engines, belts, drives, and transmissions
  • Reduction in power consumption and maintenance costs
  • Resistance to corrosive atmospheric agents

The two most common uses for carbon fiber composite fabrications are in applications where high strength-to-weight and high stiffness-to-weight ratios are desirable. These include aerospace, military structures, robotics, wind turbines, manufacturing fixtures, sports equipment, and many other advanced industrial applications.

Learn more about CarboSix carbon fiber profiles at our website.