Feature based on interviews from July/August 2023, published online in February 2024. Roles, product ranges and projects refer to that period.
From wood-filled filament to powders and pastes, several additive manufacturing routes are developing. The launch of Forust, then a Desktop Metal subsidiary, renewed questions about producing end-use wood parts. What materials, applications and obstacles distinguish these approaches?
“Wood 3D printing” covers different materials and processes. In FDM/FFF, composite filaments typically combine a thermoplastic polymer with wood fibres or particles. Binder-jetting powders and extruded pastes use other formulations; their binders should not all be described as ingredients of thermoplastic filament. Some approaches aim to reuse wood waste, but environmental performance depends on the process, formulation and end-of-life route.
Type of wood materials
Binder jetting offers another route. Forust describes a technology combining wood by-products with binders to produce parts with digitally reproduced grain. The process announced in 2021 was described as using sawdust and lignin. The Forust system overview also distinguishes printing, powder recovery and post-print infiltration: final performance depends on the complete workflow.
In addition to powder, wood can also be available in the form of pellets. Industry SE, a machine manufacturer based in Sweden is utilizing this type of material for their 3D printers. Jonas Carlsson, the company’s CEO explains that this process is interesting both in terms of “material costs and print efficiency”. “We work mainly with Stora Enso, one of the largest forest- and wood companies in Sweden. They have developed a material called Durasens 50 and 30. The Durasense 50 contains 50 % of sawmill dust, and the Durasense 30 contains 30%. Stora Enso has a MAGNUM 3D printer installed at their facilities in Hyltebruk, Sweden. They have used our machine for developing the material, and also do production within their OneLoop concept. [A bar chair can be printed in less than 2.5 hours for example]. It is possible to reuse this material up till 20 times. After the 3D printed product has reached its end-of-life, you simply shred it into pellets again and print it in the MAGNUM again,” he adds.
Furthermore, in Israel, another team of scientists is developing a wood-based paste for 3D printing. Shany Barath, Disrupt.Design Lab (D.DLab) told 3D ADEPT that “certain materials have been developed within the Disrupt. Design Lab (D.DLab) at the Technion Israel Institute of Technology. This development process involves design-led iterative exploration aimed at creating a printable wood paste. Additionally, collaborative efforts extend to industry partners like Daika Wood, involving experimentation with their waste-based materials. The material arrives as a powder, and through experiments with different formulation ratios, we define the suitable paste for our printing requirements. Utilizing natural binders, sawdust derived from industrial waste can be efficiently repurposed for applications in 3D printing. The employed printing technique hinges on the principles of Liquid Deposition Modeling (LDM), a choice substantiated by the inherent material properties, akin to the procedures utilized in printing clay-based materials.”
Another approach is being explored by Ashley Beckwith, an MIT graduate and founder of Foray bioscience: producing plant-based materials through cell culture. This is not the first laboratory use of plant cells. Research presented by MIT in May 2022 studied zinnia cells grown in a gel, with tunable properties and shapes.
The researchers hoped to extend the method to other species, including trees such as pine. Zinnia does not produce wood: these experimental results did not yet demonstrate industrial production of construction timber or a replacement for forestry.
Applications: Is industrialization possible?
While most of these wood 3D printing solutions have already produced viable prototypes, it should be noted they do not always target the same vertical industry.
With FDM 3D printing and binder jetting, some of the interesting applications that have already been publicly shared, have been made for the consumer goods industry.
FDM 3D Printing
Material producer Fillamentum for instance offers Timberfill, a material made up of wood fibers, specifically spruce fibers. “The composite material Timberfill is specifically designed for 3D printing needs, specifically for FDM/FFF technology, so the length of the fibers had to be taken into account. Timberfill was developed by mixing PLA-dominated biopolyesters and wood fibers obtained from spruce trees. The development process involves mixing biopolyesters and wood fibers in the desired ratio, typically 15% wood fibers and 85% PLA. The printed objects have an authentic look and a temporary smell of wood. We currently offer 8 color shades and are preparing more. Thanks to the bio-sourced origin of the material, it is 100% biodegradable by industrial composting” Barbora Jurčová, head of Research & Development explains.
The composition and composting claims quoted are those stated in this interview. Bio-based origin alone does not establish compostability; industrial composting requires specific conditions and does not imply degradation in nature. The supplier’s material page describes Timberfill as a biopolymer blend containing 15% natural fibres.
As far as applications are concerned, the material can be used to develop 3D-printed speakers like the one developed as part of the Spirula project in cooperation with Akemake.
In the interview, Jurčová recommended a nozzle diameter of at least 0.5 mm, suitable drying, and adjustment of temperature, layer height and printing speed. She also discussed a hardened nozzle to limit wear. These recommendations are not a universal printing profile: current Fillamentum documentation describes Timberfill as non-abrasive. Settings should be checked for the formulation, nozzle and printer being used.
Other applications involve all kinds of decorative objects, artistic sculptures, furniture models, personalized gifts and even functional parts with the appearance of wood. The versatility of wood fiber filament 3D printing opens up opportunities in a variety of industries, especially design, art and prototyping.
As far as industrialization is concerned, it should be noted that several factors can limit the development of filaments with wood fibers. “There are limited mechanical properties (mainly fragility) compared to traditional materials such as metals or plastics. Furthermore, it is the low-temperature resistance of the material, which is due to the polymer used. For some users, the need to dry the filament before using it, as well as the use of a nozzle with a larger diameter, can be limiting. And last but not least, it is a higher price compared to standard PLA or ABS filaments,” Jurčová outlines.
At the time of the interview, Timberfill was available in 8 colours, which can deliver “an authentic-looking wooden surface”. According to the company, the potential for robotic 3D printing opens up possibilities for manufacturing large-scale objects, bolstering the case for industrial adoption.
Pellet 3D printing
While the consumer segment has a great potential, the combination of wood-polymer composite pellets and 3D printing has already delivered interesting applications in architecture.
The examples presented here do not establish a business model for every application. Repeatability, throughput, final properties and cost need to be assessed for each project.
Wood-based paste deposition (LDM)
D.DLab’s WoodenWood project illustrates the use of wood-based paste. It combines a solid timber frame with robotically deposited surfaces in research exploring the reuse of wood waste.
According to Barath, the toolpath creates a rattan-like texture from sawdust, while the timber frame also supports deposition. The team’s initial aim was a prototype demonstrator, with possible applications in construction, architecture, fashion and product design. These avenues are not all industrialized applications.
At the manufacturing level, the material formulation is suited for LDM printers (such as clay printers) that are based on air pressure. However, the developed design to manufacturing workflow requires knowledge in computational design and robotic tool pathing techniques. The truth is, the use of natural materials within LDM printing requires establishing specific protocols to handle the inherent shrinkage and subsequent drying processes effectively.
What might slow down the adoption of this technology is the disruption in the fabrication processes. Considerations such as overhangs, bridging, slumping, drying, etc. become more exaggerated as the print grows in scale. Therefore, adjustments to the formula and print toolpath are needed, and this requires further research and experimentation. In addition, apart from its design-oriented nature, mechanical testing is essential for evaluating the performance of the process at different scales, Barath outlines.
While it is too soon to speak about industrialization, it should be noted that in the long run, they seek to achieve applications tailored to the construction industry.
Conclusion
The processes described in this 2023 feature offer distinct opportunities in decorative objects, furniture, composite parts and plant-material research. Scaling production depends on formulation, drying, repeatability and required performance. These examples illuminate the challenges without establishing a single maturity level for all wood 3D printing.
This dossier has first been published in the July/August 2023 edition of 3D ADEPT Mag.
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