Glass Fibres
Glass fibre materials tend to be more affordable than carbon fibres and exhibit lower stiffness. This reduced stiffness contributes to a more balanced performance, enhancing the rigidity of the material while avoiding extreme brittleness. Furthermore, glass fibres do not present concerns with radio shielding.
The relatively neutral colour of glass fibers allows for the creation of vibrant hues, exemplified by products like Polymaker HT-PLA-GF, which features colours inspired by brands such as Ryobi, Makita, Milwaukee, and Dewalt.
Carbon Fibres
Carbon fibre materials are characterised by their exceptional rigidity and tensile strength, although this increase in stiffness can lead to greater brittleness. Generally, carbon fibres possess higher heat deflection temperatures and improved dimensional stability during both printing and annealing.
However, the extreme rigidity of carbon fibres can pose a disadvantage in designs requiring flexibility. Additionally, carbon fibres may present challenges in applications like radio housings.
Want to read more? Carbon Fiber vs. Glass Fiber Filled Filaments
When Not to Use Fibre Reinforcement
In instances where flexibility is essential—such as in snap-fit designs or living hinges—it's advisable to avoid fibre-reinforced filaments. It often refer to the need for strength when they are actually seeking ductility. While fibre-reinforced materials provide greater resistance to flex and breakage, they typically exhibit lower elongation at break, making them unsuitable for applications that require some flexibility.
Want to Read more? Comparison of Chopped vs. Milled Carbon Fibre Filament
Use Case Example
If you are using Polymaker ASA finds that their hinge is breaking, and if the design can't be modified, switching to Polymaker PETG would be advisable rather than opting for a fibre-reinforced version. This is because fibre-reinforced materials tend to limit flexibility.
Technical data supports this: Polymaker ASA has an elongation at break of 6.7%, whereas Polymaker PETG boasts an elongation at break of 9.33% in the X-Y direction. Therefore, PETG would provide a more flexible and resilient option. In contrast, fibre-reinforced variants—such as Fiberon PETG-CF and Fiberon ASA-CF—have elongation at break values of 5.7% and 1.8%, respectively, making them inferior choices for this specific application.
Effects of Base Material
PLA with Fibers
While PLA is naturally stiff yet brittle, the addition of fibres may offer a unique surface finish, although the benefits are more limited.
- HT-PLA-GF is a high-temperature PLA that can withstand heat through annealing. While PLA alone would warp during annealing, the inclusion of glass fibres significantly enhances rigidity, allowing for high-temperature applications while maintaining the part's shape.
Nylon with Fibers
Nylon serves effectively as a matrix material, being tough and durable even without the addition of fibres. Incorporating fibres improves rigidity while maintaining the material's durability, unlike other fibre-reinforced filaments that may exhibit increased brittleness.
- PA6: The most durable option, providing the highest performance in dry applications but is sensitive to moisture.
- PA12: Offers stable performance in both wet and dry conditions, though it comes at a higher cost.
- PA612: Merges the advantages of both PA6 and PA12, providing a balanced performance.
Nylon is highly hygroscopic, resulting in different characteristics in its "Dry" and "Wet" states. In the dry state, it appears stiffer and stronger, while in the wet state, it becomes ductile and impact-resistant.
PET & PETG with Fibres
These co-polyesters exhibit versatility and moisture insensitivity, making them easy to print and ideal for everyday projects.
- PETG: Offers an economical option with great print ability and low warping, suitable for engineering applications requiring rigidity.
- PET: Offers more versatility due to its semi-crystalline nature. When reinforced with fibers, it provides high rigidity, dimensional stability, and excellent heat resistance (130 to 150˚C after annealing).
ASA with Fibres
ASA is already robust, and adding fibres enhances its rigidity, although this can slightly decrease impact strength and increase brittleness.
The main advantage of ASA-CF is its combination of rigidity, UV resistance, heat resistance, and low creep properties.
PPS with Fibres
PPS stands out as a high-performance material owing to its semi-crystalline structure. When reinforced with fibres, it enhances print ability.
- Polymaker's PPS offering is low-warp, flame-retardant (UL94-V0 certified), chemically resistant (at temperatures below 200˚C), and heat-resistant up to 250˚C after annealing.