Those who follow the composites industry know that researchers are putting everything they have into developing 3D printing technologies. 3D printing has the potential of completely replacing manual layups if science can perfect the process. To that end, printing processes continue to mature with every new innovation.
One of the more recent innovations combines the principles of carbon fiber additive manufacturing (CFAM) with those of injection molding and extrusion. The best of all three processes are put together to create a system capable of 3D printing ever larger parts without sacrificing speed, quality, or integrity.
Challenges of 3D Printing
Despite the amazing things 3D printing can accomplish, it is by no means perfect. 3D printing with composites is rife with challenges. For example, how do you keep printed material in place long enough to cure, even while new layers are being laid on top? Either your continuous material needs to be rigid enough to stay in place or you have to print around a scaffold.
The limits of 3D printing are not a problem for manual layups. For example, when technicians at Utah-based Rock West Composites prototype a new part using manual layups, they apply multiple layers of carbon fiber fabric in a tool, impregnate the fabric with epoxy resin, and put it into an autoclave to cure. The tool provides the structural support that keeps everything in place until the part is finished.
Achieving that same sort of thing with 3D printing is not so easy. Thus the idea of combining principles from CFAM, injection molding, and extrusion.
A New Way of Printing
This new way of printing starts with continuous carbon fiber thread that arrives at the manufacturing facility in large spools. The leading edge of the thread is fed into the printer in a fairly straightforward process. A second printhead supplies the thermoplastic material that combines with the thread during the printing process.
What is that thermoplastic material? It depends on the part being made. The process relies on plastic pellets contained in a printer in much the same way plastics are fed into an injection mold machine. The printer melts the plastic before sending it through the printhead and combining it with the carbon fiber thread.
This printing method allows for the use of different plastic products. The plastic itself still makes up the largest portion of the finished product with the carbon fiber acting as its underlying support. It is the thread that gives the product rigidity during printing. Thus, layers remain in place while they cure.
Faster Automated Printing
Making this printing system work for each kind of part is a matter of choosing the right plastic and additive. Get that right and there really is no limit to what can be printed – at least in theory. Best of all, printing is faster and can be automated.
Like printing anything else with a 3D printer, automation is a matter of writing a program that tells the printer exactly what to do. A well-written program that passes all of its tests can be left to print parts on its own. Technicians need only reload the machine with materials and inspect individual parts to ensure consistency and adherence to tolerances.
3D printing is by no means ready to completely replace manual layups. But engineers are getting closer with every new innovation. Today’s 3D printers are capable of so much more than their first-generation predecessors. It seems only a matter of time before they take the lead in producing all sorts of carbon fiber parts in a variety of shapes and sizes.