If you were building a bike frame and could choose between carbon fiber and wood, which material would you choose? It is a safe bet that carbon fiber would be the obvious choice in nearly every case. And yet, it’s quite possible that carbon fiber might find itself in competition with wood at some point in the near future.
Thanks to research being undertaken at the University of Maine, in partnership with the U.S. Department of Energy’s Oak Ridge National Laboratory, wood fiber products fabricated with 3D printing technology are right around the corner. The research focuses heavily on what is known as cellular nano fiber (CNF) technology.
3D Printing Carbon Fiber
Creating a carbon fiber part using a 3D printer starts with choosing the right carbon fiber thread. That thread is manufactured by subjecting carbon molecules to high heat and pressure. The high heat and pressure forces the molecules to align end-to-end to create a long chain that behaves very much like any other kind of thread.
Carbon threads can be used in any number of ways. For 3D printing purposes, thread is run through a printhead where, upon outflow, it is married with a resin and laid in place. A carbon fiber reinforced plastic is created when the two materials fuse together and cure.
3D printing with carbon fiber allows parts to be made in place without the need for manual layups, expensive tooling, and autoclave curing. While the technology is limited for now, it shows great promise for carbon fiber fabricating down the road.
3D Printing Wood Fiber
Printing with wood instead of carbon is quite similar in principle. Nano and micro cellulose fibers are joined together to make a thread product similar to carbon fiber thread. The resulting material is then fed through a similar printhead and married with an epoxy resin.
The resulting material is every bit a reinforced thermoplastic. The wood fibers perform the same function in the resulting material as the carbon fibers in a carbon fiber reinforced plastic. They provide additional structural rigidity without adding significantly to weight.
As for their strength as compared to carbon fiber, there is not enough data yet to reach any definitive conclusions. But even if nano and micro-cellulose reinforced thermoplastics turn out to be not as strong as their carbon fiber counterparts, it’s likely they could still be used for nonstructural parts in much the same way recycled carbon fiber is.
Bringing Down Composite Prices
Salt Lake City’s Rock West Composites says the appeal of wood fiber products is mainly in their cost. Carbon fiber is as expensive as it is because producing it requires a tremendous amount of energy. Even when 3D printing is the chosen fabrication method, carbon fiber is still more costly than most other building materials. Wood fiber plastics would be different.
We already have the technology in place for transforming wood into nano and micro cellulose fibers. Not only that, the process is comparatively cheap. It is conceivable that wood fiber plastics could offer the cost benefits certain industries need to delve more deeply into composites.
According to Composites World contributor Scott Francis, successful research at the University of Maine could also be a boon to that state’s timber industry. As the world is transitioning away from wood-based products for construction and manufacturing, the timber industry needs to develop a new customer base. That customer base could very well be established through wood fiber composites.
Carbon fiber currently has few competitors. That could change in the future, with wood fiber becoming carbon fiber’s chief rival.
