Continuous fiber 3D printing involves reinforcing plastic parts during the 3D printing process. Fiber strands– carbon fiber strands, for example– are woven into the print while it is being created.
This promising technology can prove to be highly beneficial, as long as parts are optimally designed and printed with the right settings. Here are a few tips from Artem Naumov, a Quality Engineer at Anisoprint.
Keep fiber direction in mind
Using continuous fiber strands can provide significantly increased strength and stiffness to parts, if the fibers are placed in the right direction. That’s why the correct model orientation is important.
A general rule is to place the 3D model in such a way that load vectors mostly lay in the XY plane (flat down).
Figure out load distribution
Another reason to think about proper model orientation is the load distribution inside your part.
When one continuous fiber strand goes entirely (without cuts) from one end of the model to the other, the load will be well transferred through it, with an increase in strength and lower probability of matrix breakage.
If your part is large enough and the load acts not only on the outer edges but also on the central area of the part, it is also necessary to reinforce the internal volume.
Choose reinforcement type depending on load scheme
Thanks to the nature of 3D printing, fibers can be laid in almost any direction within the XY plane. A proper combination of infills, solid layers, and fiber perimeters allows the optimization of your part for every possible load.
Choosing a reinforcement type that fits your load scheme can also save you tens of dollars on every single part.
Optimize fiber volume ratio
Fiber volume ratio plays an important role in the mechanical performance of your part. In most continuous fiber 3D printing technologies, the value can vary from 0% to 30% of continuous fiber in the end part.
In each case, you must find the balance between strength and robustness of your part on one hand, and production costs on the other hand.
Choose the right plastic
Choosing a plastic that meets your needs is very important. While the fibers will be the one carrying the loads, inter-fiber adhesion is solely defined by your matrix. Other properties– thermal, chemical, and mechanical– are also dependent on the type of filament you use.
The good news is that the current choice of thermoplastics on the market is huge. It varies from prototyping plastics like PLA to engineering plastics like PETG, PC, or PA. All of them are compatible with CF (continuous fibers).
Tolerance to limitations results in big profit
Continuous fiber has a minimal layup curve radius, and the minimal width of a reinforced element depends on the fiber’s diameter.
This means that your current part, which is typically cast or milled, will require some adjustments in order to be produced with the CFC (Composite Fiber Co-extrusion) process. You will get a strong, lightweight, relatively cheap, and easy-to-produce part in return, though!