Is “Carbon Fiber” 3D Print Material Really “Carbon Fiber”?

By on July 18th, 2017 in materials

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 A sheet of woven carbon fiber
A sheet of woven carbon fiber

Recently a number of 3D print companies have announced what’s described as “carbon fiber” materials, but are these really as strong as carbon fiber? 

Carbon fiber is a wonder substance that when combined with resin to form a composite, results in a very strong and light material. It’s been used in many exotic applications that have grown a powerful reputation for the material. 

Carbon fibers are created in long strands on spools, and then often woven into sheets that are applied with resin to form the strong carbon fiber shapes, as shown at top. This is why many carbon fiber objects have a very regular pattern on their surfaces. 

Enter desktop 3D printing, where the typical build materials are the relatively low-strength ABS and PLA plastics. Their relative weakness drove a need by some users to seek stronger materials. 

One way to make existing 3D print materials stronger is to combine them with other materials to form composites, and that’s what was done a few short years ago when the first carbon fiber 3D printer filaments were announced. 

How was this done? Carbon fibers were chopped into very short lengths and then mixed in with standard 3D printer plastic resin, then extruded into filaments and wound out spools. 

By necessity, the lengths of the chopped carbon fiber must be far less than the diameter of the extrusion nozzle, typically 0.4mm wide. If the segments were longer than that, they’d quickly clog the nozzle. 

This means that your carbon fiber filament is quite different from “regular” carbon fiber: it does not involve long continuous strands of carbon fiber, but instead has non-contiguous carbon fiber bits. 

This is not to say that carbon fiber filament is not stronger than normal filament; it is indeed significantly stronger, particularly when mixed with relatively strong plastics such as nylon. But it is by now means as strong as traditional applications of carbon fiber. 

There’s a key word to watch for: reinforced. Many carbon fiber filament offerings now are described as “carbon fiber reinforced”, which is technically correct and more accurately describes the product. However, many still refer to the material as “carbon fiber filament”. 

At the end of the day, you can only 3D print with the filaments you have, and today “carbon fiber reinforced” filament is among the strongest you can use. 

That will be the case until someone commercializes this experiment that potentially could 3D print in actual, continuous carbon fiber strands. 

Image Credit Wikipedia

By Kerry Stevenson

Kerry Stevenson, aka "General Fabb" has written over 8,000 stories on 3D printing at Fabbaloo since he launched the venture in 2007, with an intention to promote and grow the incredible technology of 3D printing across the world. So far, it seems to be working!