Minimizing mechanical anisotropy in fused filament fabrication through innovative thermoset materials and additive manufacturing processes

The additive manufacturing technology “fused filament fabrication” (FFF) provides an efficient way to produce parts and assemblies over a large spectrum of designs and materials. However, insufficient mechanical strength across interlayer bonding surfaces causes anisotropy in the printed parts. This drawback cannot fully be alleviated by process parameter optimization. Two innovative research approaches are pursued to solve this problem. In the project “HM3D”, the project consortium develops a novel thermoset filament that can be processed on ordinary FFF printers similar to thermoplastic filaments. First trials have shown that the printed parts achieve significant covalent cross-linking across layer interfaces after a thermal curing cycle, thereby potentially eliminating mechanical anisotropy. The project “EpoxySpacePrinter” takes this approach a step further by utilizing a continuous fiber reinforced thermoset filament, which is deposited in a system of two cooperating 6-axis robots, thereby increasing in-plane strength and eliminating the need to deposit the filament within a fixed X-Y-plane. The possibility to extrude the filament also in Z-direction as well as in any other orientation - without support structure or any moulding tool - allows for a load-path compliant part design and structure, thereby enabling real 3D printing in filament based additive manufacturing.

Subjects

Additive Manufacturing

Filament

Thermoset

DDC Class

600: Technology

620: Engineering

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Minimizing mechanical anisotropy in fused filament fabrication through innovative thermoset materials and additive manufacturing processes