3D printing | Carbon fiber | Composites | Fiberglass | Manufacturing
Carbon fiber 3D printing is an emerging technology with massive potential and new composite materials to be discovered yet. When Thomas Edison in late 1800s used it as filament in the early-stage of lightbulbs development, he would never imagine that during the third decade of the 21st century, 3D printing with carbon fiber would be a $10 billion market.
Carbon fiber nowadays is used to enhance composites’ material properties such as strength, stiffness, thermal resistance and durability. In this case, using the term reinforced composites with fibers reflect the reality from the material properties point of view.
The most common of such composites are carbon fiber, fiber glass and Kevlan and because of their benefits they are used extensively in military, aerospace, automotive and oil and gas industries.
Advantages of Composites in 3D printing
The traditional composite manufacturing approach is not only very time consuming as it includes multiple procedures but is also based on manual labor to properly laydown layers of composite fibers, which will have to be followed by curing equipment and molds. The whole process is definitely a non-efficient process when we talk about batch production.
Hence in 3D printing the entire procedure is driven by the user’s input on a specific software and then simply the part will be produced. Most of the time post-process work will be needed to achieve the desired surface finish and roughness.
3D printing with carbon fiber-reinforced filaments is a faster and more cost-effective manufacturing approach.
3D Printing Carbon Fiber Applications
There are two major methods to use carbon fiber in composites, the first by 3D printing with the reinforced filaments and the continuous carbon fiber reinforcement.
• Carbon Fiber Filament
In this manufacturing approach short strands of fiber (usually less than 1mm in length) are mixed with a thermoplastic material such as PLA, ABS, Nylon, PETG or PEEK which will be used as the base for the final mix. The fibers will enhance the mix by increasing its strength and stiffness but will also reduce the total weight in comparison to the base thermoplastic material. Fibers are known to withstand adequately reasonable applied stresses and as a result a common thermoplastic material to obtain rigidity and better mechanical properties.
Moreover, carbon fiber will allow the manufactured component to have a more stable behaviour under low or high temperatures. Experts in the field recommend to use hardened steel nozzle to avoid clogging the 3D printer’s nozzles.
• Continuous Carbon Fiber Reinforcement
This method can be considered as the improved approach compared to the previous one simply because the fibers are not chopped in small pieces hence, they keep most of their rigidity and strength. This technique is used in demanding applications to replace metallic structures such as aluminium as it reduces the cost at half the weight.
There are two types of this additive manufacturing approach, depending on the time the carbon fiber is added in the 3D printing process. If added prior the extrusion process, then the process is called prepreg-based and if they are added during the extrusion process, it is called co-extrusion. In any case, the carbon fibers remain continuous and they are infused in the polymer base material with a process called pultrusion.
What is pultrusion process?
Pultrusion is the manufacturing method that forms continuous lengths of FRP (fiberglass reinforced plastic). In this process, the material product has continuous constant cross sections. The coated/soaked fibers are then passed through preforming guides in order to align and re-orient reinforcement preparing the parts to the desired shape before they enter into a heated die. The temperature of the die is carefully controlled to ensure that the component is fully properly cured with controlled heat and cooling channels in the die.
How it compares with other composites?
ABS Carbon Fiber
While ABS is the most common polymer for consumer products it can also work as a solid base for new composites due to its stable properties. An ABS fiber product will have an excellent surface finish and allow the engineer to use it as a prototype or even end-use product. The only disadvantage of ABS fiber is that a heated build chamber is a required which can be found on expensive 3D printer models.
Nylon Carbon Fiber
Nylon as a famous material already holds the sceptre in engineering because of its highly desirable properties. Mixing it with carbon fiber will result in a very popular, strong composite with high resistance and durability. The drawback of this material is that it is able to contain bound moisture meaning that the material is considered hygroscopic.
PETG Carbon Fiber
PETG (Polyethylene terephthalate glycol) with carbon fiber can form a very effective composite in applications where the component is exposed in chemicals and moisture. PETG is a well known material for its liquid ingress protection.
Glass fiber can be considered as a good alternative to carbon fiber in 3D printing. It is used in applications where flexibility in the final product is required. The mechanical properties of glass fiber composite are very similar to carbon fiber’s.
The best way to summarise the fundamentals of carbon fiber is a table where the advantages and disadvantages can be summarised.
While 3D printing is not considered as a young technology anymore, composite 3D printing still within the manufacturing industry. 3D printed composites such as carbon fiber, offer enduser parts with excellent properties assisting the engineers in using high performance parts in demanding industries such as automotive and aerospace. Finally, they are clearly materials that will attract many companies due to their lightweight structures and reduced costs.
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3D printing and Sustainability