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A novel process named ‘individual layer fabrication (ILF)’ is presented, in which objects are built up by laminating individually contoured wood-based panels. However, contrary to the well-known process of ‘laminated object manufacturing (LOM)’, in ILF, the individual panels are not shaped by a subtractive process but additively by selective binding of wooden particles. The particles are spread as a thin layer onto a built platform. A liquid adhesive is then applied only to those areas where the contoured panel is to be generated. As each layer is fabricated individually, the ILF process allows the application of mechanical pressure. Thereby, compared to other additive manufacturing techniques, the necessary amount of binder can be significantly reduced and mechanical properties comparable to particle boards can be achieved.

The renewable resource, wood, is becoming increasingly popular as a feedstock material for additive manufacturing (AM). It can help make those processes more affordable and reduce their environmental impact. Individual layer fabrication (ILF) is a novel AM process conceived for structural applications. In ILF, parts are formed by laminating thin, individually contoured panels of wood composites which are fabricated additively by binder jetting. The individual fabrication of single panels allows the application of mechanical pressure in manufacturing those board-like elements, leading to a reduction of binder contend and an increase of mechanical strength. In this paper, the ILF process is described in detail, geometric and processing limitations are identified, and the mechanical properties of the intermediate product (panels) are presented. It is shown that the thickness of panels significantly influences the geometric accuracy. Wood composite panels from spruce chips and pMDI adhesive showed flexural strengths between 24.00 and 52.45 MPa with adhesive contents between 6.98 and 17.00 wt %. Thus, the panels meet the mechanical requirements for usage in the European construction industry. Additionally, they have significantly lower binder contents than previously investigated additively manufactured wood composites.

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