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Rapid, large-volume, thermally controlled 3D printing using a mobile liquid interface

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Science  18 Oct 2019:
Vol. 366, Issue 6463, pp. 360-364
DOI: 10.1126/science.aax1562
  • Fig. 1 Flow profile of a mobile interface that enables continuous printing.

    (A) Scheme of a 3D printed part emerging from the HARP 3D printer. (B) Velocity profile under printed part at different flow speeds, demonstrating the presence of a slip boundary. Colors represent increasing volumetric fluxes q (red, q = 0.21 mm/s; orange, q = 0.30 mm/s; green, q = 0.44 mm/s; teal, q = 0.56 mm/s; blue, q = 0.66 mm/s; violet, q = 0.75 mm/s). Open circles are experimental data points from particle-imaging velocimetry; continuous lines are fits from an analytical model. (C) Scheme inset of the slip boundary flow profile under the part, with a representative experimentally observed flow profile.

  • Fig. 2 IR thermal images of an emerging 3D printed part (hard polyurethane acrylate resin; cross section, 5 cm × 5 cm; vertical print rate, 120 μm/s; optical resolution, 100 μm) under three different print conditions.

    (A) Stationary print interface. (B) Mobile interface. (C) Mobile interface with active cooling. Elapsed time between panels (left to right) is ~500 s; scale bars, 25 mm. Data and thermal color mapping correspond to movies S1 to S3.

  • Fig. 3 Manufacturing-ready materials and resolution.

    (A) Type I dog-bone structures made from an ABS-like polyurethane acrylate resin exhibit isotropic mechanical properties (ASTM D638) and are comparable to a part cast from the same resin (black line) as well as injection molded ABS (gray line). (B) HARP also enables high spatial resolution and print fidelity, as evidenced by the variation between designed and printed features as a function of feature size down to ~300 μm (below this, the ability to resolve parts becomes inconsistent) using a light-patterning engine with an optical resolution of 100 μm. Data points are mean values; error bars represent SD across 10 5-mm posts printed in differing regions of the print bed. Red dashed lines represent the bounding constraints of ±1 pixel for the light-patterning engine. (C) A computed tomography (CT) scan between a printed part (print rate, 120 μm/s; optical resolution, 100 μm) and its CAD design file reveals a volumetric correlation of 93%. Blue and purple volumes represent the printed object and the CAD object, respectively. Scale bar, 1 cm. (D) Representative height profile scans along the print direction for a series of 3-mm-thick dog bones for varying widths [red, 1 mm; green, 2 mm; blue, 4 mm; black, 6 mm; see additional data in (24) for dog bones 1 to 2.5 mm thick]. Red dashed lines represent the bounding constraints of ±1 pixel for the light-patterning engine. (E) Analysis of the profilometry data allows for the calculation of the arithmetic surface roughness, Ra, of the printed parts as a function of minimum feature dimension and reveals a strong linear correlation with a Pearson correlation coefficient of r = 0.90 (n = 20, rcrit = 0.444 for P = 0.05). (F) Despite this surface roughness, the maximum tensile stress remains invariant of the feature size (data points are mean values; error bars represent SD across five Type IV dog bones, ASTM D638). The inset shows a scatterplot for each dog bone, revealing a Pearson correlation coefficient between the surface roughness and maximum tensile stress of r = –0.34 (n = 25, rcrit = 0.396 for P = 0.05). The hard polyurethane acrylate resin was used for all experiments in (B) to (F).

  • Fig. 4 A wider palette of resins.

    (A) A hard, machinable polyurethane acrylate part (print rate, 120 μm/s; optical resolution, 100 μm) with a hole drilled against the print direction. Traditional noncontinuous layer-by-layer printing techniques typically delaminate and fracture when drilled in this orientation. (B) A post-treated silicon carbide ceramic printed lattice (print rate of green polymer precursor, 120 μm/s; optical resolution, 100 μm) stands up to a propane torch (~2000°C). (C and D) A printed butadiene rubber structure (print rate, 30 μm/s; optical resolution, 100 μm) in a relaxed state (C) and under tension (D). (E) Polybutadiene rubber (print rate, 30 μm/s; optical resolution, 100 μm) returns to expanded lattice after compression. (F) A ~1.2-m hard polyurethane acrylate lattice printed in less than 3 hours (vertical print rate, 120 μm/s; optical resolution, 250 μm). Scale bars, 1 cm.

Supplementary Materials

  • Rapid, large-volume, thermally controlled 3D printing using a mobile liquid interface

    David A. Walker, James L. Hedrick, Chad A. Mirkin

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Supplementary Text
    • Figs. S1 to S9
    • Captions for Movies S1 to S8
    • References

    Images, Video, and Other Media

    Movie S1
    IR Thermal Mapping with No Flow (corresponds to Fig. 2A of main text; see Fig. 2A for scale); Video plays at 100x actual speed.
    Movie S2
    IR Thermal Mapping of Flow with No Cooling (corresponds to Fig. 2B of the main text; see Fig. 2B for scale); Video plays at 100x actual speed.
    Movie S3
    IR Thermal Mapping of Flow with Cooling (corresponds to Fig. 2C of the main text; see Fig. 2C for scale); Video plays at 100x actual speed.
    Movie S4
    Drilling of Machinable Hard Urethane Acrylate Resin (corresponds to Figure 4A of the main text); Video plays at actual speed.
    Movie S5
    Flame Test of Silicon Carbide Ceramic Print (corresponds to Figure 4B of the main text); Video plays at actual speed.
    Movie S6
    Butadiene Rubber of Varying Elasticities (corresponds to Figure 4C,D of the main text); Video plays at 100x actual speed.
    Movie S7
    Compression of Butadiene Rubber Lattice (corresponds to Figure 4E of the main text); Video plays at 100x actual speed.
    Movie S8
    Print of 30 cm x 30 cm Hex-Tube Lattice (corresponds to Figure 4F of the main text); 3D latticed printed at 120 μm/sec. Play speed is at 100x real speed.

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