Additive manufacturing has grown quite a bit in its 30 year existence. But what’s more impressive is the maturation of desktop 3D printing within the last 10. What was once a collection of hobbyist DIY kits and projects printing mostly PLA and ABS (with mixed results at best) has developed into a range of products that can serve even the most demanding professionals using more exotic materials such as carbon fiber and other composites.
With this rapid expansion of exotic materials comes a learning curve. For this article, we’ll discuss carbon fiber as a material, going through some of its history, benefits, and applications, and of course, the things you will want to know before you start with carbon fiber 3D printing.
Carbon fiber comes in many different forms. It can be used in conjunction with resin and molds; it can be combined with polymers in composite form. It has been used for everything from lightbulbs to high performance race cars - and is even being tested on Mars-bound rockets. While applications are wide ranging, the most obvious benefit of carbon fiber is it’s high strength-to-weight ratio.
Carbon fibers were first discovered by Thomas Edison in the late 19th century for use as filament in early lightbulbs. In the late 1950’s, The Union Carbide Corporation first realized the strength benefits that could be achieved through further processing techniques. Over the next 50 years, manufacturing techniques advanced further, and today carbon fiber has become ubiquitous with high performance products from race cars to airplanes.
In general, all carbon fiber is produced starting with a six step process. PAN (polyacrylonitrile) is obtained as a byproduct of petroleum and is typically the preferred material from which carbon fiber is produced. PAN is mixed with other ingredients and spun into fibers which are as thin as 10% of the thickness of a human hair. The fibers are then oxidized to stabilize bonding before going through carbonization during which the fibers are heated to temperatures of 1000° C to remove impurities. The surface is then treated to improve bonding before the final step of sizing in which fibers are coated and spun into different thickness yarns.
High performance racing teams in Formula 1 and other circuits need to be strong and lightweight to maximize speed and agility. The stiffness of carbon fiber combined with its low weight makes it the perfect material.
Cutting edge aerospace developments have shown carbon fiber to be a fantastic material for reinforcing wings and bodies of airplanes and are even being tested for next-generation rockets - in both cases, lightweight means more fuel can be carried and longer ranges can be achieved.
Many sporting goods companies have dabbled in using cutting-edge composites of carbon fiber to gain a competitive advantage - especially when it comes to professional athletics such as cycling and golf.
Factories, machine shops, and other manufacturing facilities that use robotics might use carbon fiber 3D printing to produce end of arm tools that can sustain a high degree of force while taking up the minimum amount of the robotic arm’s lift capacity.
3D printing carbon fiber means choosing the right composites for your application. The base polymer can dictate final properties of the part as well as the considerations that go into the 3D printing experience. Below, you’ll see a variety of composites in carbon fiber 3D printing and some of their strengths and weaknesses.
|Heat Deflection (ASTM 648, 66 psi)||363°F||184°C|
|Tensile Strength (ISO 527)||16,000 psi||110 MPa|
|Tensile Modulus (ISO 527)||1,102,000 psi||7,600 MPa|
|Strain at Yield (ISO 527)||2%||2%|
As mentioned earlier, nylon 3D printing in FDM is a bit difficult but with the right tools it can be used to produce consistent results. We will start with some of the common challenges with nylon 3D Printing.
Nylon carbon fiber is one of the more popular composites when it comes to carbon fiber 3D printing. That’s because nylon n already possesses desirable properties for engineering tasks. It has a high degree of strength and a high heat resistance. It also has a high degree of durability which balances out the brittleness of the carbon fiber itself. A potential drawback for nylon is its hygroscopicity making it all the more important to have a protected environment for spools of nylon carbon fiber, such as a mylar bag and a sealed material bay.
ABS is a well known material thanks to its common use in injection-molded consumer products. In carbon fiber 3D printing, ABS works as a solid base polymer because of its properties. ABS carbon fiber also tends to have a very nice surface finish which is almost always welcome whether the application is a prototype or end-use part. One downside of ABS carbon fiber is that it requires the use of a heated build chamber which is typically only found on higher end 3D printers.
PETG is a material known for its resistance to chemicals and moisture in general making it a good composite polymer for carbon fiber 3D printing in applications that experience such exposure. Examples of these applications include parts that will encounter coolants or simply products that will be outdoors in rainy climates.
Carbon isn’t the only fill material when for 3D printing composites. Glass fiber is an alternative to carbon fiber 3D printing when a more flexible end product is desired. It can be composited with many of the same types of materials and can yield high strength in a similar way to carbon fiber.
➜ Strong and Lightweight: Carbon fiber’s most well known property is its strength to weight ratio which is why it is frequently used in performance products. This is thanks to its low density.
➜ Heat Resistance: Carbon fiber is able to withstand higher temperatures than many polymers and even increase the HDT of those polymers when mixed in to form a composite.
➜ Stiffness: While some polymers may have high strength and durability, this often comes at the expense of stiffness. Carbon fiber’s ability to maintain its shape under high stress is a huge plus for many applications.
➜ Expensive: Due to carbon fiber’s complex manufacturing processes, the material has been known to be more expensive making it a luxury, which is one reason why it appears in high end products but not in the mass market.
➜ Brittle: One downside of high stiffness is that carbon fiber can shatter under high impact force. This means that applications with such forces are not going to be ideal for carbon fiber.
Carbon fiber composites materials can either be bought from filament manufacturers or 3D printer manufacturers. For the MakerBot METHOD, we recommend the use of MakerBot Nylon Carbon Fiber as it is optimized to deliver great results. Other carbon fiber 3D printing composites for METHOD can be found in MakerBot LABS.
Looking for a professional 3D printing platform that works with a variety of manufacturing-grade materials? Learn more at makerbot.com/carbon.