3D printed carbon fiber is the second most sought-after additive manufacturing technology after metal. Relying on the latest developments in the field of additive manufacturing, people are finally realizing the ability to print using a variety of elusive materials. However, not all carbon fiber 3D printers are the same—some machines use microscopic chopped fibers to reinforce traditional thermoplastics, while others use continuous fibers laid inside a thermoplastic matrix (usually filled with chopped fibers). Create a "skeleton" inside the part.
Detailed explanation of the role of carbon fiber in 3D printing
Carbon fibers are composed of aligned carbon atom chains and have extremely high tensile strength. Using them alone is not particularly useful-their thin and brittle nature makes them easy to break in any practical application. However, when an adhesive is used to group and bond the fibers together, the fibers will distribute the load smoothly and form a very strong, lightweight composite material. These carbon fiber composite materials come in the form of sheets, tubes or customized molding features, and are used in aerospace and automotive industries, where the strength to weight ratio is dominant. Generally, thermosetting resins are used as adhesives.
The latest developments in 3D printing technology have enabled the company to use carbon fiber for printing, although the bonding material used is different from the standard carbon fiber process. The resin does not melt, so it cannot be extruded through the nozzle-to solve this problem, the 3D printer replaces the resin with a thermoplastic that is easy to print. Although these parts are not as heat resistant as resin-based carbon fiber composites, they do benefit from the strength of the fiber.
At present, the use of 3D printing additive manufacturing technology for carbon fiber reinforced plastics and composite materials (SCFT, LCFRT, CFRP, and CFRTP) has become a rapidly developing digital, intelligent, and automated high-tech new technology for the preparation of carbon fiber composite materials at home and abroad. technology. Compared with the traditional carbon fiber composite material molding and preparation process, it has simple process, low processing cost, high raw material utilization rate, green production technology and environmental protection, reduces manufacturing cost of parts, and realizes structural design and manufacturing of composite parts Complete integration, no need to open mold manufacturing, can repeatedly digital mold repair and printed parts verification, which can speed up the development cycle, save development costs, and can be used as an effective technical solution for low-cost rapid prototyping manufacturing. Carbon fiber reinforced plastics and composite materials in aerospace and military industry can use 3D printing technology to manufacture lighter, stronger industrial-grade lightweight composite materials complex structural parts. The high cost of carbon fiber (CF), the complicated preparation process conditions and control, the lack of special processing and molding special equipment and the lack of professional engineering and technical personnel make it less developed and applied in the 3D printing industry, but in the end of various industries at home and abroad The potential for application development is huge, especially in the research and development of aerospace and new energy electric vehicles with broad application prospects and development.
Printing carbon fibers by FDM melt extrusion requires printing carbon fiber composite materials with hot melt plastics. For example, using hot melt plastics such as PETG. PETG material itself has good ductility, and it can withstand more The high CF load maintains a certain degree of ductility and impact resistance. It can adhere well to a variety of construction platforms, and also has excellent layer bonding, and the addition of carbon fiber can also increase its rigidity and dimensional stability. The XT-CF20 printing material of the Dutch colorFabb company contains Eastman Chemical's PETG material and 20% carbon fiber material. 3DXTECH also uses Eastman PETG material combined with high modulus carbon fiber to make a composite material. Another company, Proto-PAsta's carbon fiber-reinforced material PLA, is a synthesis of a derived plastic derived from corn starch and a carbon fiber composite material.
Carbon fiber 3D printing method
There are currently two carbon fiber printing methods: chopped carbon fiber filled thermoplastics and continuous carbon fiber reinforced materials. Chopped carbon fiber-filled thermoplastics are printed by standard FFF (FDM) printers and consist of thermoplastics (PLA, ABS or nylon), which are reinforced by tiny chopped strands, or carbon fibers. On the other hand, continuous carbon fiber manufacturing is a unique printing process that lays continuous carbon fiber bundles onto a standard FFF (FDM) thermoplastic substrate.
Although chopped carbon fiber filled plastic and continuous fiber manufacturing also use carbon fiber, the difference between them is very large. Understanding how each method works and its ideal application will help you make informed decisions and determine what steps should be taken in additive manufacturing.
Chopped carbon fiber is basically a reinforced material of standard thermoplastics. It allows companies to print generally weaker materials with higher strength. The material is then mixed with thermoplastics, and the resulting mixture is extruded into spools used in molten filament manufacturing (FFF) technology. For composite materials using the FFF method, the material is composed of chopped fibers (usually carbon fibers) mixed with traditional thermoplastics (such as nylon, ABS, or polylactic acid). Although the FFF process remains unchanged, chopped fibers increase the strength and rigidity of the model, and improve dimensional stability, surface finish, and accuracy.
This method is not always flawless. Some chopped fiber reinforced filaments emphasize strength by adjusting the supersaturation of the material with fibers. This will adversely affect the overall quality of the workpiece, thereby reducing surface quality and part accuracy. Prototypes and end-use components can be manufactured using chopped carbon fiber because it provides the strength and appearance required for internal testing or customer-facing components.
Continuous carbon fiber is the real advantage. This is a cost-effective solution that can replace traditional metal parts with 3D printed composite parts, as it can achieve similar strength using only a fraction of the weight. It can use continuous filament manufacturing (CFF) technology to embed the material in a thermoplastic. Printers using this method lay continuous high-strength fibers (such as carbon fiber, glass fiber, or Kevlar) in the second printing nozzle in the thermoplastic extruded through the FFF when printing. Reinforced fibers constitute the "backbone" of printed parts, producing a hard, strong and durable effect.
Continuous carbon fiber not only increases strength, but also provides users with selective reinforcement in areas where higher durability is required. Due to the FFF nature of the core process, you can choose to strengthen layer by layer basis. In each layer, there are two types of reinforcement methods: concentric shaft reinforcement and isotropic reinforcement. Concentric filling enhances the outer boundary of each layer (inner and outer) and extends into the part through a user-defined number of cycles. Isotropic filling forms a unidirectional composite reinforcement on each layer, and carbon fiber weave can be simulated by changing the reinforcement direction on the layer. These strengthening strategies have enabled industries such as aerospace, automotive and manufacturing to integrate composite materials into their workflows in new ways. Printed parts can be used as tools and fixtures (these require continuous carbon fiber to effectively simulate metal properties.), Such as tools at the end of the arm, soft jaws, and CMM fixtures.
Carbon fiber 3D printing technology
Laser sintering technology
Material characteristics: Short fiber reinforced nylon, PEEK, TPU and other powder materials Process characteristics: Mix chopped carbon fiber and nylon material in a certain ratio, and achieve integrated molding through laser sintering.
2. Multi-jet fusion technology
Material characteristics: Short fiber reinforced nylon, PEEK, TPU and other powder materials Process characteristics: Through the heating of the lamp tube, under the action of the cosolvent, enough heat is collected from the cross section of the part to achieve melt molding.
3. FDM technology
Material characteristics: Long fiber reinforced PLA, nylon, PEEK and other wire materials
Technological characteristics: FDM technology is used to fill long fibers into conventional wire materials and play a reinforcing role.