Army

3-D printed preforms thermally drawn into fibers and filaments

Creates parts with high mechanical and functional properties, as well as reduced surface roughness that also maintain geometric accuracy

Materials

(a) Two-color ABS preform with the ARL logo. (b) A multi-lumen microfluidic preform, consisting of a printed, white four-vaned PC core inserted into a transparent, extruded PC sheath. (c) A dual-material preform, consisting of a five-spoked PC core and mating red ABS insert. (d) Green ABS preform with three perimeter flow channels and one central channel for hosting the glass optical fiber.

3-D printing technology (additive manufacturing) creates physical models from computational models, usually layer upon layer. The subset of processes that create physical models by melt-depositing thermoplastic filaments are referred to a fused filament fabrication (FFF) which is synonymous with fused deposition modeling and plastic jet printing.

Quality of FFF products is based on a combination of precise geometry, high strength and stiffness combined with such other characteristics as electrical conductivity or optical clarity. Maximizing each of these is difficult since thermoplastics exhibit viscoelastic thermal softening – stiffness and viscosity reduces as the temperature is increased. Since both high-flow and high-mechanical stability conditions cannot be met simultaneously with a single polymer, FFF is typically executed at a compromised temperature at which weld lines partially fuse, providing a moderate level of mechanical robustness, and at which there is a moderate but acceptable level of geometric sag, shrinkage, or warpage

Army researchers have made a breakthrough in advancing the process for making optical fiber via additive manufacturing which yields FFF parts and monofilaments with high functional properties and high geometric stability. These components can have complex and tailorable cross sections for precision optical waveguiding, varying indices of refraction, as well as designed scattering, reflective, or absorbing properties. In this approach preforms or filaments are built up from materials such as thermoplastic, glass, metal, edible material, or other material. The filaments or preforms contain two or more polymers of differing flow temperature arranged in a geometric pattern within the filament or preform cross-section. The lower flow temperature (LFT) polymer fills the voids and forms strong weld lines, while the higher flow temperature (HFT) polymer remains mechanically stable to retain dimensional stability. By printing or annealing FFF parts within this processing window, parts with high mechanical and functional properties, as well as reduced surface roughness that also maintain geometric accuracy can be produced.

In addition to the manufacturing of optical fibers, this process can produce microfluidic fibers, such as would be used in vascularly accessed medical procedures in which multiple flow cavities are contained within a single fiber. Additionally, it could create fibers with images, text, symbols, logos, or a barcode microscopically incorporated into the fiber cross-section – useful for anti-counterfeiting, tagging, identification, tracking, or beautification of specialized goods and materials.

This US application number 20180087189 is related to US application number 20160281267.

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