Carbon Fiber Tow

Carbon fiber tow is the primary form of carbon fiber before it is converted into a finished carbon fiber reinforcement, most often a woven carbon fiber cloth. Carbon fiber tow is available in many different sizes but most commonly in 1k, 3k, 12k and 24k; the 'k' number refers to the number of thousands of individual carbon fiber filaments that are bunched together to make up the tow; so a 3k tow is 3,000 individual fibers and a 12k tow is made up of 12,000 individual fibers. Likewise yarn is the name used for aramid fiber in its basic fiber form, the size or thickness of an aramid yarn is typically described in terms of its 'tex' count.

In commercial or R&D settings, tow and yarn can be used to weave carbon fiber or aramid cloth, supply a pultrusion line or feed a filament winding machine. At a smaller scale, tow and yarn can be used to add local reinforcement in projects like R/C planes, gliders, boats and other models. They can also be wrapped tubes or vessels to increase their burst or crush strength.

In all cases, dry carbon fiber tow must be combined with a resin, such as epoxy, in order to create a rigid composite reinforcement.