Composites, the best of next-gen materials, have long been beleaguered by the lack of automation in its fabrication. The hand-layup process has abysmal rates of production (2.5 lbs/hour) and is very expensive while also being detrimental to human health. The fabrication of composites is a very challenging task on account of its extreme strength, abrasive nature, technical specificity required and the high degree of variation inherent in composites manufacturing. The presence of such formidable challenges has made the rapid and low-cost automation the holy grail of composite production.
Innovations have happened along the way, ex. Automated Fiber Placement (AFP) and Automated Tape Layup (ATL) processes which have ramped up the production rate to 50 lbs/hr, a 20-fold improvement over manual lay-up, but their level of integration is still low. But the need for faster and more versatile production still remains.
Taking things further, most firms have directed their investment and research into the advancement of 3D printing, for composites. The reason is simple; additive manufacturing seems to be the most promising solution for complete automation of composite production.
Of late, firms have successfully scaled the production speed, size and accuracy of the manufacturing process by roping in robots, parallelizing or use of multiple robots etc.
Advancements & Innovations
The biggest advantage of composites is their anisotropic property, which makes them many times stronger than conventional material. This property is best embodied by continuous composites, but with concurrent higher fabrication costs and complexities.
The efforts in 3D printed fiber composites seem to diverge in two main directions; one way focuses on mass production with low cost and the other focuses on a small batch size of products which have highly complex geometries with a need for high part accuracy as well.
Enumerated below are the technological advancements that have recently happened. Most of them strive towards the attainment of mass production at low costs.
Continuous-Fiber 3D Printing (CF3D): A mouldless, out-of-Autoclave (OAA) manufacturing process, is the intended outcome of the partnership between Spatial Corp. (a subsidiary of Dassault Systèmes) & Continuous Composites, in 2019. CF3D will use Continuous Composites’ continuous-fibre 3D printing (CF3D) process and Spatial’s 3D software. CF3D takes 3D printing beyond the traditional stacking of 2D layers, facilitated by the use of an industrial robot with in situ impregnation and a rapid-curing thermoset resin inside the print head, which is then pulled through the print head and cured using a high-intensity energy source (UV, heat, etc.), instantaneously resulting in a true 3D composite part. “The economics of CF3D will result in the mass adoption of composites in a variety of new industries and applications.” its engineers believe.
Arevo, the famous 3D printed e-cycle maker, has made many new developments. Direct energy deposition (DED) stands out with its 100-fold faster production speed achieved via its rotating build platform, an industrial robot, a printhead with laser heating and running multiple printheads per robot or multiple robots per work cell. Arevo has shown a decisive move towards mass production and staunch belief in the merit of in situ inspection as the way to go.
CEAD’s Continuous Fibre Additive Manufacturing (CFAM) technology (2019) is created to fill the present gap of lack of large scale industrial printing, as envisioned by its founder Lucas Janssen. CEAD offers the Robot extruder (featuring four heating zones) and its gantry-based CFAM Prime machine. The robotic arm can move at 4 m/min, which is very fast for a robot and offers multi-axis printing which can overcome the current challenge with z-direction properties. CEAD is developing 5-axis machines combining the two systems; the gantry system is faster, but this new system offers true multi-axis placement.
Orbital Composites has been very verbal about its intention of producing humungous quantities or objects and has been following the developmental philosophy is “material agnosticism” i.e. Orbital’s technology is designed to adapt to nearly any composite material which is presently used by industries. Its radical Coaxial extrusion end effectors, extensive use of parallel robotics and OOA processes expedite production 100 times vis-a-vis conventional methods.
In February 2019, 9T Labs (Switzerland) began beta testing of its CarbonKit which is designed to make existing 3D printers capable of continuous fiber printing, and for mass adoption along with industrial serial printing. Its variable extruder head can accommodate high-resolution applications with small tow, as well as big area additive manufacturing with large tow.
The Small Batch Innovations
There is a segment of manufacturing that can only be done via 3D printing. For instance, highly complex and integrated parts like stiffened grids with its high strength/stiffness-to-weight ratios; there are parts of aircraft (an example) that are required in very low quantity making a capital investment in mould or mandrel unjustifiable. A few firms have oriented their future endeavours to cater to this niche segment.
University of South Carolina’s Ronald E. McNair Center for Aerospace Innovation and Research have collaborated with TIGHITCO and Ingersoll Machine Tools to develop continuous fiber-reinforced 3D printing for highly complex applications demanding high accuracy as well.
Arturs Bergs, TIGHITCO project engineer at the McNair Center, articulates the firm’s objective to make accurate parts with least post-processing than vice-versa. Michel van Tooren, McNair Center professor, highlights that apart from other advantages, Overprinting is one leading advantage facilitated by their new machine. Overprinting involves the insertion of a component during the print cycle which gets fully embedded in the main structure thus eliminating the need for rivets, fasteners and bonding adhesives, resulting in a superior structure. This radically improves the level of integration (while working with thermoplastics).
In general, the 3D printed parts are printed, layer upon layer, thus compromising on its Z-axis strength. An object 3D printed by means of fused filament fabrication (FFF) may not be as strong on the Z-axis as it is on the X and Y-axes.
To bring isotropic strength to FFF 3D printing, the partnership (2016) between Essentium Materials and FFF printer manufacturer Cosine Additive created an FFF printer capable of achieving powerful levels of Z-axis strength. Once a number of layers are printed, the device applies an electric field to fuse the layers together, ensuring isotropic strength.
The future course of 3D Printed Composites
Though the present market of 3D printed composites is less than 0.1% of the total composite market, the market is experiencing high growth. Stratview Research analysts prognosticate that the global 3D-printed composite market will grow at a CAGR of around thirty percent over the next five years to reach a market size of over US$ 180 million by 2024. The growth gets reinforced further by the recent advancements which are directed towards the democratisation of 3D printed composites.
MarkForged, the pioneer of continuous fiber-reinforced 3D printing technology (2014), is selling its latest (2017) X7 printer (50X faster & 20X cheaper) and working on a closed-loop process for full integrated material tracing and comprehensive automatic reporting. Jon Reilly, MarkForged VP of products, anticipates the current market for continuous fiber reinforced 3D printing technology which is dominated by high-value & low-volume parts to grow towards relatively high-volume, low-value parts as printer manufacturers reduce? printing and material costs. “3D print companies that don’t invest for scale will lose out.” he believes. Painting a roseate picture, MAI Carbon Cluster Management GmbH, believes that the production costs of carbon fiber could soon be lowered by 90 percent, reinforcing the possibilities of mass adoption.
Many in the traditional composites industry are questioning how 3D printed continuous fiber composites can compete with conventional composites when they have such low fiber content and such high potential for delamination between the printed layers. “For sure, z-direction strength is one of the most challenging things for 3D printed composites.” Logtenberg, CEAD co-founder, agrees, but innovations like the one done by Essentium Materials shall come in handy, eliminating the existing bottlenecks.
With rapid advancements, the shift to 3D composite printing seems inexorable now.
Find out in greater detail the current market of 3D printed composites through Stratview Research’s report. Follow the link below