by Merve Canalp, Researcher at AMEXCI
During “Composite Workshops 2021”, four virtual workshops with the participation of high-performance polymers and composites AM companies were held successfully during Q4 2021. The main material focus was on Composite AM Technologies including Robotic Material Extrusion (by Ai Build), Composite Based Additive Manufacturing (by Impossible Objects and Ricoh), Fiber Placement Additive Manufacturing (by 9T Labs), and Composite Thermoplastic Material Extrusion (by Roboze).
With the help of article series, we would like to introduce some of the most prominent AM companies and their technologies which took part in the Composite Workshops 2021. And in this second part, we are going to introduce Impossible Objects and Composite-Based Additive Manufacturing (CBAM).
Part II: Composite-Based Additive Manufacturing presented by Impossible Objects and Ricoh
Impossible Objects & Ricoh: Composite-Based Additive Manufacturing (CBAM), developed by Impossible Objects (IO), is a type of Continuous Fiber Sheet Lamination process which enables printing sheet fiber, e.g., carbon or glass, reinforced parts held together by thermoplastic polymer matrix such as Polyetheretherketone (PEEK) or Polyamide (PA12, Nylon).
CBAM technology benefits lie in printing dimensionally stable parts with fine details, while having excellent strength-to-weight ratio. As of Spring 2021, IO provides parts to Ricoh UK for customers based in the EU.  
A closer look at CBAM Technology
Overall CBAM printer build size is 30,5 cm x 30,5 cm x 10,2* cm (*taller height might be possible for custom applications). CBAM printing involves several steps in realizing the final part as shown in Figure 2.
Printing Process (Step 1): After feeding the sheet into the inkjet printer, a binder is fed onto the sheet according to the CAD design, and following that, the selected thermoplastic polymer powder is deposited on top, which adheres to the binder-soaked area. The excess polymer powder is removed by vacuum. Only powder stuck on top of the binder stays on the fiber sheet. This process is repeated for creating each layer, and finally all layers are stacked on top of each other to create the 3D part out of the 2D sheets.
Heat and Press (Step 2): After all layers are printed, the stacked sheets are placed in a pressure oven where the polymer powder melts as the layers are stuck during compression.
Material Removal (Step 3): Finally, the unstacked parts of the print job are removed with the help of blasting revealing the final part.
What are the different CBAM Materials?
Thermoplastics exhibit different properties and depending on their performance under heavy loads; thermoplastics are divided into three main categories: high performance polymers, engineering polymers, and commodity polymers as shown in Figure 3. High performance polymers are preferred over commodity polymers for applications requiring high temperature resistance and excellent mechanical performance.
Currently, CBAM utilizes two different polymers as matrix materials:
- Polyamide (PA12, Nylon): A semi-crystalline engineering polymer (Tg = 35-45 °C, Tm = 175-180 °C)
- Polyetheretherketone (PEEK): A semi-crystalline high-performance polymer (Tg = 140-145 °C, Tm = 340-345 °C)
In addition to higher temperature endurance limit of PEEK, which belongs to the family of high-performance polymers, it also has higher mechanical properties than PA12.
There are two fiber reinforcement materials employed by CBAM technology:
- Glass Fiber (GF, Fiberglass)
- Carbon Fiber (CF)
In CBAM, fiber reinforcement properties vary according to the type of the chosen fiber. For instance, GF which is cheaper in price, has less tensile strength whereas it is more ductile than CF.
CBAM nonwoven composite veils and mats are typically composed of engineered fibers of 12.5 to 25mm in lengths with random fiber orientations (Figure 4). The fiber sheet and polymer powder are bound together with an organic polymer binder. The final CBAM part contains high levels of fiber (up to 80%). Compared to other AM technologies and feedstock materials, this high volume of fiber reinforcements provides better mechanical properties for the end products (Figure 5). On the other hand, filaments used in material extrusion have lower than 1 mm fiber length. For powder-based technologies, e.g., SLS, composite powder contains fiber particles measured in microns or nanotubes.
Composite parts printed by CBAM
Impossible Objects have been working on development of new solutions for printing composite materials in collaboration with Ricoh Japan, Owens Corning, Tiger and BASF. Currently, four different types of composite thermoplastics are available for printing low to medium volume production cases.
- Carbon Fiber Nylon (CF-PA12)
- Fiberglass Nylon (GF-PA12)
- Carbon Fiber PEEK (CF-PEEK)
- Fiberglass PEEK (GF-PEEK)
The application spectra of such composites are quite broad, from tools to electrical components in various industries such as in aerospace, automotive and energy. Depending on the product requirements and costs, a suitable combination of matrix and fiber reinforcement can be selected from CBAM materials portfolio.
During this workshop, both Impossible Objects and Ricoh UK presented and shared details about this evolving AM technology and composite AM materials. With the help of this virtual workshop, we had the chance to learn more about:
- Current and upcoming developments on IO’s side, regarding material development and CBAM technology advancements
- An overview of IO’s and Ricoh’s business structure and their partnership
- Both IO’s and Ricoh’s internal/external capabilities and networks
- Case studies and possible application areas through direct interaction.
All in all, we had the chance to witness closely that in some cases CBAM can offer a fast way to produce functional, high quality and performance parts. Since the process involves stacking of fiber sheets and polymer powder with the help of a binder, flat parts low in height (< 6-8 mm) would benefit from this AM technology the best when it comes to achieving better accuracy in dimensionality. Printing of such flat parts with CBAM will be also cost and time efficient. As Amexci, we aim at following new developments on CBAM technology and materials together with IO and Ricoh UK.
In the next part of this article series, we will dive deep into Fiber Placement Additive Manufacturing and the workshop presented by 9T Labs, summarizing some key takeaway notes from the workshop held in 2021.
 Technical datasheet of Carbon PEEK can be found from here: https://rapidfab.ricoh-europe.com/wp-content/uploads/2021/03/Ricoh-TDS-CF-PEEK-FINAL-WEB.pdf.
 Please see the information about the pricing from Ricoh UK’s website: https://rapidfab.ricoh-europe.com/3d-materials/impossible-objects-and-ricoh-3d-sales-samples/.
About Merve Canalp
Merve Canalp works as a Researcher at AMEXCI and her expertise lies in the field of polymer materials. Her daily tasks include investigating Polymer AM applications and managing corporate R&D projects.
For more information, or if you would like to discuss polymer AM, get in touch with Merve at: firstname.lastname@example.org