Additive Timber Manufacturing: A Novel, Wood-Based Filament and Its Additive Robotic Fabrication Techniques for Large-Scale, Material-Efficient Construction

Abstract

Additive manufacturing (AM), as resource-efficient fabrication processes, could also be used in the dimensions of the construction industry, as a variety of experimental projects using concrete and steel demonstrate. In timber construction, currently few additive technologies have been developed having the potential to be used in large scale. Currently known AM processes use wood in pulverized form, losing its inherent structural and mechanical properties. This research proposes a new material that maintains a complete wood structure with continuous and strong fibers, and that can be fabricated from fast-growing locally harvested plants. We describe the material technology to create a solid and continuous filament made of willow twigs and investigate binding and robotic AM methods for flat, curved, lamination, and hollow layering geometric typologies. The resulting willow filament and composite material are characterized for structural capacity and fabrication constraints. We discuss our technology in comparison with veneer-based lamination, existing wood filament printing, and fiberbased AM in terms of fabrication, material capacity, and sustainability. We conclude by showing possible applications in the construction industry and future research possibilities.

Wood-Veneer-Reinforced Mycelium Composites for Sustainable Building Components

“…This allows for complex tool paths, the creation of multi-directional reinforcement patterns and controlled anisotropy. Two approaches can be used for the layering: placing the veneers with the same direction or similar directions at once, then moving on to the next layer ( Figure 2 ); or printing one line from a different direction at a time, which results in a structure with interwoven fibers [ 31 ].…”

“…Precedents of continuous wood fiber laying research have explored synthetic binders, such as UV-curing glue, contact glue and hot melt glue [ 31 ]. Since mycelium growth is incompatible with synthetic materials, and the goal of producing a 100% bio-based composite cannot be achieved with the binders investigated to date, it was necessary to research alternative binding methods.…”

“…In recent years, researchers proposed a fabrication method for architectural elements, using continuous natural timber fiber filaments through robotic fabrication [ 30 , 31 ]. The aim was to produce structural elements by combining the advantages of continuous fiber-based manufacturing with bio-based materials.…”

HOME: Wood-Mycelium Composites for CO2-Neutral, Circular Interior Construction and Fittings

“…Various timber species (beech -Fagus sylvatica, spruce -Picea abies, maple -Acer pseudoplatanus, Oak -Quercus robur) were tested. Additionally, printing tests were performed using a solid filament produced from split willow withies [23].…”

A screw extrusion-based system for additive manufacturing of wood: Sodium silicate thermoset composites

“…38 There are other examples of using wood in AM that do not involve thermoplastics. Eversmann et al 39 used solid wood filament from willow twigs and glue to 3D print large-scale timber components using a robotic arm similar to that of a veneer-based lamination process. Ghanbari-Ghazijahani et al 40 evaluated the feasibility of printing composite sandwich beam elements with honeycomb cores made from timber and PLA to compare the flexural capacity of conventional beams used in the construction industry.…”