An official website of the United States government
Abstract Aerosol jet printing offers high resolution, broad materials compatibility, and digital patterning for flexible, conformal, and hybrid electronics. However, limited throughput, instability, and complex optimization requirements inhibit translation to industrial applications. An in‐line heater integrated on a custom printer is demonstrated to modulate droplet evaporation in the aerosol phase, thereby decoupling the deposition rate of functional solids and liquid ink to enable taller, narrower features with aspect ratios reaching 0.29 for a single line. Heating the printhead from room temperature to 80 °C reduced the sensitivity of resolution to deposition rate by ≈90%, improving reliability. With this strategy, increasing the linear deposition rate by 10x results in a modest increase of 27% in line width, compared to a four‐fold increase without heating, permitting higher throughput without sacrificing print quality. Providing a control for in‐line drying independent of ink formulation enables rapid, straightforward design of new materials and processes. This ability to engineer drying of droplets prior to impingement provides a versatile tool to meet complex fabrication challenges, as demonstrated here for both high aspect ratio printing and conformal patterning on rough and three‐dimensional surfaces.
more »
« less
Dual Extrusion FDM Printer for Flexible and Rigid Polymers
Commercially available fused deposition modeling (FDM) printers have yet to bridge the gap between printing soft, flexible materials and printing hard, rigid materials. This work presents a custom printer solution, based on open-source hardware and software, which allows a user to print both flexible and rigid polymer materials. The materials printed include NinjaFlex, SemiFlex, acrylonitrile-butadiene-styrene (ABS), Nylon, and Polycarbonate. In order to print rigid materials, a custom, high-temperature heated bed was designed to act as a print stage. Additionally, high temperature extruders were included in the design to accommodate the printing requirements of both flexible and rigid filaments. Across 25 equally spaced points on the print plate, the maximum temperature difference between any two points on the heated bed was found to be ∼9°C for a target temperature of 170°C. With a uniform temperature profile across the plate, functional prints were achieved in each material. The print quality varied, dependent on material; however, the standard deviation of layer thicknesses and size measurements of the parts were comparable to those produced on a Zortrax M200 printer. After calibration and further process development, the custom printer will be integrated into the NEXUS system — a multiscale additive manufacturing instrument with integrated 3D printing and robotic assembly (NSF Award #1828355).
more »
« less
- Award ID(s):
- 1828355
- PAR ID:
- 10310613
- Date Published:
- Journal Name:
- 15th International Manufacturing Science and Engineering Conference
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Plasma jet printing is an emerging alternative to popular 2-D printing techniques, such as inkjet and aerosol jet printing. The inherent nature of the plasma provides films with good adhesion upon printing without the need for thermal sintering. The reduced logistics and the ability to print a wide range of materials on rigid and flexible substrates make it a valuable technique for printed and flexible electronics. In this tutorial article, we discuss the principles behind plasma printing, printer hardware, and printing mechanisms and provide representative print results.more » « less
-
Binder jetting (BJ) is an additive manufacturing process that uses a powder feedstock in a layer wise process to print parts by selectively depositing a liquid binder into the powder bed using inkjet technology. This study presents findings from high-speed synchrotron imaging of binder droplet-interaction during the BJ printing process. A custom laboratory-scale BJ test platform was used for testing which enabled control of relevant process parameters including powder material, print geometry, spacing between droplets, powder bed density, and powder moisture content. Powder ejection was observed above the powder bed surface and powder relocation due to droplet impact was observed below the powder bed surface. Powder relocation was observed to be sensitive to powder material, powder bed density, powder bed moisture, droplet spacing, and print geometry. Increasing powder bed density was found to increase particle ejection velocity but reduce the total number of particles ejected. Process parameters that increase binder / moisture content in the powder bed were found to reduce powder ejection. The number of ejected powder particles was reduced for lower droplet spacings. Both powder ejection and powder relocation below the powder bed were reduced by treating the surface of the powder bed with a water/triethylene glycol (TEG) mixture before printing. Results from this study help to build understanding of the physical mechanisms in the BJ printing process that may contribute to formation of defects observed in final parts.more » « less
-
Additive manufacturing promises to revolutionize manufacturing industries. However, 3D printing of novel build materials is currently limited by constraints inherent to printer designs. In this work, a bench-top powder melt extrusion (PME) 3D printer head was designed and fabricated to print parts directly from powder-based materials rather than filament. The final design of the PME printer head evolved from the Rich Rap Universal Pellet Extruder (RRUPE) design and was realized through an iterative approach. The PME printer was made possible by modifications to the funnel shape, pressure applied to the extrudate by the auger, and hot end structure. Through comparison of parts printed with the PME printer with those from a commercially available fused filament fabrication (FFF) 3D printer using common thermoplastics poly(lactide) (PLA), high impact poly(styrene) (HIPS), and acrylonitrile butadiene styrene (ABS) powders (< 1 mm in diameter), evaluation of the printer performance was performed. For each build material, the PME printed objects show comparable viscoelastic properties by dynamic mechanical analysis (DMA) to those of the FFF objects. However, due to a significant difference in printer resolution between PME (X–Y resolution of 0.8 mm and a Z-layer height calibrated to 0.1 mm) and FFF (X–Y resolution of 0.4 mm and a Z-layer height of 0.18 mm), as well as, an inherently more inconsistent feed of build material for PME than FFF, the resulting print quality, determined by a dimensional analysis and surface roughness comparisons, of the PME printed objects was lower than that of the FFF printed parts based on the print layer uniformity and structure. Further, due to the poorer print resolution and inherent inconsistent build material feed of the PME, the bulk tensile strength and Young’s moduli of the objects printed by PME were lower and more inconsistent (49.2 ± 10.7 MPa and 1620 ± 375 MPa, respectively) than those of FFF printed objects (57.7 ± 2.31 MPa and 2160 ± 179 MPa, respectively). Nevertheless, PME print methods promise an opportunity to provide a platform on which it is possible to rapidly prototype a myriad of thermoplastic materials for 3D printing.more » « less
-
Magnetic Field Assisted Additive Manufacturing (MFAAM), 3D printing in a magnetic field, has the potential to fabricate high magnetic strength anisotropic bonded magnets. Here, 10, 35, and 54 wt% strontium ferrite bonded magnets using polyamide 12 binder were developed by twin screw compounding process and then printed via MFAAM samples in zero, and in 0.5 Tesla (H parallel to the print direction and print bed). The hysteresis curves were measured using a MicroSense EZ9 Vibrating Sample Magnetometer (VSM) for 3 different mount orientations of the sample on the sample holder to explore the magnetic anisotropy. The samples printed in zero field exhibited a weak anisotropy with an easy axis perpendicular to the print direction. This anisotropy is caused by the effect of shear flow on the orientation of the magnetic platelets in the 3D printer head. For the MFAAM samples, the S values are largest along the print bed normal. This anisotropy is caused by the field. The alignment of the magnetic particles happens when the molten suspension is in the extruder. When the material is printed, it is folded over on the print bed and its easy axis rotates 90° parallel to the print bed normally. Little realignment of the particles happens after it is printed, suggesting a sharp drop in temperature once the composite touches the print bed, indicating that field-induced effects in the nozzle dominate the anisotropy of MFAAM deposited samples.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/MSEC2020-8377
