The limiting factors for 3D printing on an industrial scale are the limited choice of materials and possible print sizes using them. Here, CFIP (Continuous Fibre Injection Process) provides a remedy because it facilitates the use of affordable lightweight materials. By injecting endless fibers, the process developed by Reinforce3D from Spain, increases the stability of 3D printed parts. The flexible PC-based control technology from Beckhoff simplified the automation of the novel process in the compact Delta machine.

In general, there are four fundamental stages in additive manufacturing: design, 3D modeling, printing and post-processing. Regardless of the manufacturing technology used, the last step is especially important, as it gives the printed parts the desired surface finish. Moreover, many post-processing techniques are also used in order to enhance the physical and mechanical properties of the parts. CFIP (Continuous Fibre Injection Process) is a new post-processing technology that can potentially be a new milestone in the additive manufacturing industry. In the patented process developed by the start-up company Reinforce3D, 3D-printed parts are reinforced by the subsequent injection of continuous fibers. The advantage lies in increasing the mechanical performance while maintaining any lightweight properties.

Originally, Reinforce3D was a project within the Eurecat technology center, located in Catalonia, Spain. Together with Eurecat and former development leader Marc Crescenti, investors BeAble Innvierte Kets Fund (BIKF) launched a start-up in 2022, to further develop the CFIP technology. Under its CEO, Blanca Garro, the company succeeded in bringing its technology to maturity in a short period of time. In 2023, new head of automation Marc Roselló started to develop the Delta machine, which could be presented in that same year during the Formnext trade fair in Frankfurt. The objective of the young enterprise was to remove the boundaries for post-treatment accepted as standard until then.

Strengthening 3D printed parts from within

Instead of strengthening parts during the manufacturing process, as is common in conventional 3D printing, CFIP is improving part properties in a subsequent step. Specifically, this method involves injecting continuous fibers into pre-designed tubular cavities in the parts to drastically improve their strength. A key point to achieve this enhancement is the usage of continuous fibers instead of using short fibers because these will increase stability exponentially rather than gradually. In addition to strengthening parts, continuous fibers enable the integral bonding of different components by injecting fibers through the joints. The fiber continuity from one end to the other results in stronger bonds than those obtained with traditional joining methods, such as using adhesives. The fibers are carried by a liquid resin that seamlessly bonds with the 3D printing material after setting, creating a new physical interface and increasing the structural strength and mechanical properties of the part significantly as a result.

In addition to carbon fibers, CFIP can also be used with glass and aramid fibers. Moreover, Reinforce3D plans to expand its range of materials to include natural fibers in the future. Another advantage of the versatile method is its compatibility with a multitude of additive manufacturing methods. Therefore, users can turn to 3D printing technologies that are more suitable for volume production, such as well-known commercially available systems that work with thermoplastic polymers. Even when using these comparatively inexpensive materials, the user can achieve very good results by reinforcing the lightweight materials subsequently. In addition to plastics, the technology also works with a wide range of additive manufacturing materials, including metals and ceramics.

Unique new process and customized controls

As Marc Crescenti, CTO at Reinforce3D, explains: “CFIP is a completely new technology and Reinforce3D is exploring unknown territory, so we were looking to develop a machine that is sufficiently reliable to offer the best-possible user experience but flexible enough at the same time, so it can evolve together with the development of CFIP. After evaluating all options available, we concluded that Beckhoff provided the best solution for this application.”

The hardware core of the control solution is formed by a CX5140 Embedded PC. The powerful and compact computing device proved to be an ideal fit for this application, which demanded a balance between computing power and size. Marc Roselló emphasizes the significance of its flexibility, as the CX5140 can be easily upgraded for future needs with regularly available new processor generations. The fact that the machine design can remain unchanged is a user benefit in terms of simplicity and sustainability, according to the head of automation.

For the intricate task of fiber injection, the implementation of precise stepper motor control was paramount. This was achieved using four EL7037 1-channel motion interfaces from the EtherCAT Terminal portfolio for compact drive technology. Marc Roselló, head of automation, highlights: “This choice simplified the cabling significantly, compared to external stepper controllers solutions. Additionally, it facilitated the design of a compact control cabinet, seamlessly aligning with the design concept of the Delta machine.”

Another critical aspect of the fiber injection process is controlling the injection force to prevent material jams within the randomly formed part structures. Feedback is achieved through connecting a load cell to the EL3351 analog input terminal for direct connection of resistor bridges. This system-integrated measurement technology eliminates the need for an external amplifier, ultimately reducing complexity, conserving space and minimizing cabling efforts. Furthermore, various digital and analog I/O modules are used to integrate multiple process valves and a diaphragm pump into the control loop for resin supply.

Efficient implementation with TwinCAT

The driving force behind the successful development of the precision control solution lies not only in its hardware components but also in the software suite TwinCAT from Beckhoff, says Marc Roselló. He attests to the high user convenience and power of the automation software, particularly in conjunction with the EtherCAT stepper motor controllers. TwinCAT 3 NC PTP has proven invaluable for realizing software-based point-to-point motion control, he adds. Marc Roselló elaborates: “The engineering interface, software architecture and usability of TwinCAT have supported us throughout the familiarization period. It is straightforward, requires minimal effort, and ultimately facilitates the implementation of our core expertise.”

Highlighting the learning path, he emphasizes the wealth of training resources available with Beckhoff, coupled with the continuous support provided by Beckhoff. The unwavering availability to assist in overcoming emerging challenges has proven to be a key factor for the successful implementation.