3D printed wood warping

When a tree is cut down, drying process occurs, resulting in reduction of its volume due to water loss. Trees are in good approximation to cylindrical symmetry, which causes uneven shrinkage for different axis, in a process known as wood warping. Here we present investigation of wood warping for objects that are fabricated by 3D printing. Similar to natural wood warping, water evaporation causes volume decrease of the printed object, but in contrast, the printing pathway pattern dictates alignment that can be predesigned and affect the resulting structure after drying.

The fabrication of the objects was performed by a Direct Ink Writing (DIW), which is an extrusion based 3D printing technique, that enables deposition of water based inks into 3D objects. The printing ink is composed of 100% wood based materials, wood chips or powder, and plant-extracted natural binders- cellulose nanocrystals and xyloglucan, without the need of any additional synthetic resins. The resulting as-printed objects transformed their geometry through the evaporation of water. It was found that printing parameters such as flow rate and printing pathway, effect the morphology of the fully dried objects, and therefore it is possible to design the printing of wet objects that will form a different final 3D structures.