Carbon fiber has one of the highest strength to weight ratios of any material out there. This makes it one of the best options for manufacturers looking to create parts that are strong but still remain lightweight. The fibers themselves are made up of carbon atoms whose crystal structure is aligned into strands, making the strands incredibly strong when under tension. 3D printing with carbon fiber can be difficult at times, but the advantages it provides are hard to find with any other material.
Carbon fiber is a very difficult material to use in FDM 3D printing. For starters, carbon fiber is much more resilient to heat, so you will want to make sure your print head is set to a higher temperature, around 220 degrees Fahrenheit. In addition, since carbon fiber is stronger than steel, using carbon fiber filament with a steel or brass print head will actually begin to bore open the hole of your nozzle. Because of this, it is important to use a hardened steel nozzle, or even a sapphire nozzle to try and limit this heavy wear and tear. If you don't, you are going to have to replace your nozzle every 500 grams or so. Another thing you will want to do, is play around with the flow and retraction properties of your printer. Because this material is so gritty, it can sometimes be difficult to maintain a good level of flow and surface finish, so adjusting your printer settings will help ensure that you're getting the best print possible. Once you have the proper settings dialed in, you will be left with some great looking parts. The surface finish on carbon fiber parts looks great because the grittiness of the material really helps blend in those layer lines.
So those are the main things to be aware of when printing with carbon fiber. Although it takes a little extra time to optimize the settings of your printer for carbon fiber printing, you won't regret it because you will end up with parts that not only look better, but also function better and are more durable. So if you are looking to expand upon the materials that you print with, look into getting some carbon fiber. We're sure you won't regret it.