AeroLas GmbH (Munich, Germany) has developed a spinning process by which discontinuous carbon fiber filaments can be combined with thermoplastic fibers to form a yarn material that can be used in additive manufacturing, 3D printing and other composite materials Potential applications in the process.
Traditional ring spinning machines (right) have a traveler, which tends to destroy carbon fiber filaments. The Aerolas ring spinner (left) has two curved circular steel rings in a ring that relies on air bearing technology to rotate. Photo Credit | CW
The looper enables Aerolas to spin on carbon and thermoplastic fiber materials, making it suitable for 3D printing systems.
AeroLas' technology is a derivative of traditional spinning, which uses a ring spinning machine (see photo). AeroLas executive director Michael Muth pointed out that the ring spinning machine used to spin 80% of the world's yarns is not compatible with carbon fiber filaments. The ring-shaped "Traveller" guides the filament to the bobbin (COP) located in the center of the ring, but it is too sharp and will cause the carbon fiber filament to break.
To solve this problem, AeroLas uses air bearing technology, which the company has developed for hundreds of industrial applications for decades. As the name suggests, air bearings use compressed air instead of traditional metal bearings, creating a gap between the two friction surfaces.
Using this technology, AeroLas reconsider the rotating ring to create an annular ring design where pressurized air enters the gap between the two to facilitate rotation. This design eliminates the need for traditional travellers and allows AeroLas to switch to curved round travellers that don't break carbon fiber filaments (see photo).
Muth said the company has been studying carbon fiber of different lengths for the past few months and combining it with thermoplastic fibers to determine the optimal fiber length for the spinning process. He said preliminary results indicate that the ideal carbon fiber filament length is about 80 mm. The company created a prototype yarn that combines chopped carbon fiber with polyamide 6 (PA6) and provides samples for evaluation by additive manufacturers. Muth said initial feedback was positive. In addition, AeroLas used its materials for the JEC World 2019 show in Paris (March 12-14), where it received a lot of interest from material suppliers and original equipment manufacturers.
Muth said the process can combine technical fibers with any thermoplastic fiber, but most of the company's work to date has been with carbon fibers. In particular, AeroLas sees its spinning process as an ideal target for recycled carbon fibers. Muth notes that most recycled carbon fibers are converted into nonwovens, which, while useful, do not take advantage of the mechanical properties in the fibers.
"Airbus and Boeing have a lot of scrap and they need a solution to turn it into a usable product," Muth said. "We actually prefer to call it an upgrade cycle because our process maintains the value of carbon fiber by keeping the direction of the carbon fiber in the same direction." Muth also noted that the yarn has flexibility and a small bend radius, making it Ideal for 3D printing.
Muth said that AeroLas' next step is the industrialization and commercialization of spinning technology. Since yarn spinning is not part of AeroLas' core business scope, the goal is to form a new corporate entity, hire engineers and build production-scale spinning machines. However, this requires a lot of investment, and Muth and his team are currently seeking investment from interested investors.