Carbon fiber filaments use tiny fibers that are infused into a base material to improve the properties of that material. Several popular filaments can be bought with carbon fiber fill including PLA, PETG, Nylon, ABS, and Polycarbonate. These fibers are extremely strong and cause the filament to increase in strength and stiffness. This also means that the 3D printed parts will be much lighter and more dimensionally stable, as the fibers will help prevent shrinking of the part as it cools. Print settings, such as printing temperature, speed, bed adhesion, and extrusion rates will be very similar to the normal settings used for the base material that the fibers were added to (for example, the stock PLA settings would be a good starting point for PLA-based carbon fiber filament). However, due to the added fibers, these specialty materials are more likely to clog and can require special hardware to avoid damaging the printer.
- Increased strength and stiffness
- Very good dimensional stability
- Abrasive and requires hardened steel nozzle
- Increased oozing while printing
- Increased brittleness of filament
- Higher tendency to clog
Carbon fiber filled filaments have the same requirements as the base filament it is infused with. The hardware requirements listed below are for carbon fiber filled PLA filament.
These tips will help you reduce the chances of common 3D printing issues associated with carbon fiber filled filaments such as clogging and the nozzle wearing down.
Upgrade to Hardened Steel Nozzle
The carbon fibers in these filaments can be extremely abrasive. In many cases, the carbon fibers are actually harder than the brass nozzles used on most 3D printers, so trying to print these materials with a stock nozzle could damage the printer. Instead, plan on upgrading to a hardened steel hotend. These hotends can resist the added wear from the fibers, however, they also tend to be less thermally conductive than their brass counterparts. You may need to set the extruder temperature as much as 40° hotter than usual, which also helps with reducing the chance of a clog. Reducing the fan speed can also be useful to prevent thermal issues with the steel nozzles.
Adjust Retraction Settings to Avoid Clogs
Since the filament is full of small fibers that won’t melt, the chances of a nozzle clog are greatly increased over the base material. We recommend reducing your retraction distance or disabling retractions all together, as the retractions can increase the change of a buildup of fibers inside the extruder assembly. If you want to minimize the number of retractions that are performed, Simplify3D includes a very useful setting that will actually adjust the travel path of the extruder to stay within the interior of the part so that no retraction is needed. You can enable this setting by turning on the “avoid crossing outline for travel movements” option on the Advanced tab of your process settings.
Reduce the Print Speed for Consistent Results
Using a slower print speed can be a big benefit for carbon fiber filled materials, as the extruder will be under less stress, and has a higher chance of pushing small clogs through the nozzle if they start to form. Try reducing your print speed by 25-50% to see what value works best for your specific brand of plastic. If you still experience clogs after making these changes, we have an entire section on our Print Quality Guide dedicated to this issue that includes several other tips to help troubleshoot this issue: How to Fix a Clogged Extruder.
Use a Guided Filament Path
Carbon fiber filled filaments tend to be far more brittle than the base filament and can snap easily if they are forced through tight corners, or rub on sharp edges of the printer frame. Make sure that the entire filament path, from the spool to the nozzle, consists only of gentle curves, with no sharp turns or areas where the filament will be dragged along a surface. Using a PTFE guiding tube, or ensuring that the filament spool is in a strategic place with regards to the extruder can help reduce the chance of filament breakage.
- Nozzles with larger diameters (0.5mm or more) are far less likely to clog, as the fibers will fit through the larger nozzle hole much more easily.
- If the nozzle seems to clog right away after printing the first layer or two, try increasing the first layer height. If the nozzle is too close to the bed, this will create increased back-pressure while printing these layers that can cause the fibers to build up and clog the nozzle temporarily.
Get Started with Carbon Fiber Filled
There are many unique applications for this speciality material. We’ve compiled a few tips below to help you get started.