Why Use Composites?
Many industries including the aerospace, defense, automotive, construction, maritime and consumer products industries are increasingly turning to composite materials to make their products due to their enhanced performance. Composites can be defined as the combination of two or more constituent materials that have significantly different physical properties from one another. The advantages being that the new combined material can achieve better performance in desired areas than any one of the materials can alone. High strength and low weight products can be manufactured with composites, which can provide a major benefit for aerospace and automotive applications where strength and weight are two critical factors.
Traditionally, composites have been manufactured utilizing a layup method whereby the reinforcing fabric, typically glass fiber or carbon fiber is laid over a mold and the filler matrix that acts as a glue is applied to hold the fabric in place. The combined materials are then cured using a type of vacuum sealed oven called an autoclave. Recently, a new method, 3D printing composite materials, is starting to be utilized as well. The reinforcing material, glass or carbon fibers, are transformed into particles and are combined with a thermoplastic base, which could be nylon, ABS, or PETG, among many others. This allows the combined composite material to be melted and extruded through a nozzle into the desired shape of the product. The reinforcing fibers add additional strength, durability, stiffness and heat resistance.
Generally, many composites used for industrial applications can be broken down by the following chart. Three common 3D printing composite fibers are glass fiber, carbon fiber and Aramid (Kevlar) fibers.
Fiberglass is made by melting silica sand, limestone, and soda ash, among other minerals, and extruded to create long thin strands of glass fibers. These fibers are then oriented into various patterns. The performance characteristics of end composite material depends on the pattern of the fibers and the overall weight of the fibers. Generally, fibers can be woven or matted. Woven fibers are anisotropic, meaning they are stronger in certain directions and weaker in other areas. Whereas with matted patterns, they are shorter in length, but there is no pattern and the fibers are oriented in random directions, making it isotropic or equally strong in all directions.
Fiberglass is a very widely used composite as it is the most cost effective between itself, Kevlar and carbon fiber. It also provides the strength, heat resistance, and low weight profile that carbon fiber provides, but with more flexibility than carbon fiber or Kevlar.
3D printed fiberglass involves the use of glass fiber particles, mixed with a 3D printable thermoplastic, typically an engineering grade material such as nylon. Owens Corning, one of the industry world leaders in composites starting in the 20th century, recently introduced its brand of 3D printable fiberglass, XSTRAND, which provides many of the capabilities that traditional fiberglass provides such as impact resistance and increased strength with the advantages of additive manufacturing including high complexity, customization, prototyping and low volume production orders. Other manufacturers of fiberglass for 3D printing composite materials include BASF, that offers a Polypropylene with 30% Glass Fiber, and Clariant who offers a flame-retardant nylon 6 with 20% glass fibers. Check out ZABFAB’S fiberglass 3D printing capabilities here.
The main feature of carbon fiber is the added stiffness provided, relative to other composites such as fiberglass. Although costlier that other composites, carbon fiber has a strength to weight ratio that is five times that of steel, in addition to being highly chemically resistant, heat resistant and having a low thermal expansion. The carbon fibers are made by taking a plastic fiber, composed of thousands of filaments and chemically altering it to form a perfect chain of carbon atoms. These strands of fibers are bundled together to form a tow bundle and are mixed with a resin adhesive or thermoplastic. Like fiberglass, the orientation, length and overall weight of the fibers determines the properties of the final carbon fiber composite product.
To be used for 3D printing composite materials, these carbon fiber strands are transformed into carbon fiber particles that can be mixed with engineering grade thermoplastics. The carbon fiber provides a dramatic improvement in performance than what would have been possible with the thermoplastic alone.
Carbon fiber, due to its high strength to weight ratio is being used in many applications in industry; specifically, airplane manufacturers Boeing and Airbus have utilized carbon fiber parts on each of their Boeing 787 and Airbus A350 models respectively.
Aramid Fiber (Kevlar)
Kevlar, like fiberglass and carbon fiber, is a fabric material made of aramid fibers that is combined with a resin to make incredibly strong and impact resistant parts. Invented by Dupont, Kevlar is used for bullet proof vests, helmets and many other anti-ballistic applications, in addition to boats, gloves, tires and many more. Although not as strong as fiberglass or carbon fiber, Kevlar boosts some amazing energy absorption properties which is why is it is most well-known for its use in bullet-proof body armor.
Like 3D printing composite materials fiberglass and carbon fiber, 3D printing with Kevlar involves transforming aramid fibers into particles that can be combined with a thermoplastic matrix.
Composites in 3D Printing
Many challenges with 3D printing that remain are due to the deficit in strength versus other conventional methods. However, fiber reinforced 3D printing composite materials could open the door to provide solutions to a variety of new applications. Thermwood produced a 12 ft long tool for in support of Boeing’s 777X program with an ABS 3D printing composite material reinforced with 20% carbon fiber.
Cincinnati incorporated (CI) utilized a Glass fiber reinforced ABS to 3D print a kayak, eliminating many manual labor hours of hand layup of each layer of composite fabric.
Oak ridge national Labs 3D Printed a car with ABS material reinforced with carbon fiber.
3D printing offers some unique advantages when it comes to manufacturing including the ability to produce products with more complex geometries, customized products, and faster lead times. These advantages combined with the capabilities of composite materials could be revolutionary for companies looking for materials with an exceptional level of performance with the high accuracy, rapid solutions, and unique design possibilities that additive manufacturing offers.
Interested in using composite 3D printing material on your next project? Contact ZABFAB to learn more or check out our composite 3D printing materials. For more information on 3D printing materials, check out our Ultimate Guide to 3D Printing Materials.