3D Printer Nozzle Research Articles

A New 3D Printing Strategy by Harnessing Deformation, Instability, and Fracture of Viscoelastic Inks.

Direct ink writing (DIW) has demonstrated great potential as a multimaterial multifunctional fabrication method in areas as diverse as electronics, structural materials, tissue engineering, and soft robotics. During DIW, viscoelastic inks are extruded out of a 3D printer's nozzle as printed fibers, which are deposited into patterns when the nozzle moves. Hence, the resolution of printed fibers is commonly limited by the nozzle's diameter, and the printed pattern is limited by the motion paths. These limits have severely hampered innovations and applications of DIW 3D printing. Here, a new strategy to exceed the limits of DIW 3D printing by harnessing deformation, instability, and fracture of viscoelastic inks is reported. It is shown that a single nozzle can print fibers with resolution much finer than the nozzle diameter by stretching the extruded ink, and print various thickened or curved patterns with straight nozzle motions by accumulating the ink. A quantitative phase diagram is constructed to rationally select parameters for the new strategy. Further, applications including structures with tunable stiffening, 3D structures with gradient and programmable swelling properties, all printed with a single nozzle are demonstrated. The current work demonstrates that the mechanics of inks plays a critical role in developing 3D printing technology.

Demonstration of passive saturable absorber by utilizing MWCNT-ABS filament as starting material

This work demonstrated a stable passively Q-switched laser with the employment MWCNTs dispersed in acrylonitrile butadiene styrene (ABS) resin (MWCNTs-ABS) based filament as passive saturable absorber. The simple fabrication process of the SA is further explained, started from the process of extruding the filament through a 3D printer nozzle at 210 °C to reduce the diameter from 1.75 mm to 200 μm. It is then weighed to about 25 mg and mixed with 1 ml acetone before sonicated for 5 minutes to dissolve the ABS. The resultant MWCNTs-acetone suspension is dropped on a glass slide to be characterized using Field-Emission Scanning Electron Microscope (FESEM) and Raman spectroscopy. It is also drop-casted on the end of a fiber ferrule to be integrated in the laser cavity. The proposed work revealed that the laser oscillated at about 1558 nm with threshold input pump power of 22.54 mW and maximum input pump power of 108.8 mW. The increase in pump power resulted in the increase in repetition rate where the pulse train increases from 8.96 kHz to 39.34 kHz while the pulse width decreases from 33.58 μs to 5.14 μs. The generated pulsed laser yields a maximum of 1.01 mW and 5.53 nJ of peak power and pulse energy respectively. The signal-to-noise ratio of 40 dB indicates that the generated pulse is stable.

Design and Analysis of Fused Deposition Modeling 3D Printer Nozzle for Color Mixing

Fused deposition modeling (FDM) has been one of the most widely used rapid prototyping (RP) technologies leading to the increase in market attention. Obviously it is desirable to print 3D objects; however, existing FDM printers are restricted to printing only monochrome objects because of the entry-level nozzle structure, and literature on the topic is also sparse. In this paper, the CAD model of the nozzle is established first by UG (Unigraphics NX) software to show the structure of fused deposition modeling 3D printer nozzle for color mixing. Second, the flow channel model of the nozzle is extracted and simplified. Then, the CAD and finite element model are established by UG and ICEM CFD software, respectively, to prepare for the simulation. The flow field is simulated by Fluent software. The nozzle’s suitable temperature at different extrusion speeds is obtained, and the reason for the blockage at the intersection of the heating block is revealed. Finally, test verification of the nozzle is performed, which can produce mixed-color artifacts stably.

Experimental and numerical studies on the gas velocity deviation in a 600 MWe tangentially fired boiler

In this paper, a comprehensive method containing cold-state modeling experiment, cold-state numerical simulation, and hot-state numerical simulation is employed to analyze the aerodynamic field in a 600MWe tangentially fired pulverized boiler. To investigate the non-uniformity characteristics of flow field distribution in the horizontal flue under deep air-staged condition by this method, a major attention is paid to the gas velocity deviation in front of the final super-heater. Experiments at the cases of various yaw angles of separate over-fire air (SOFA) are carried out under a cold model of the large utility boiler with a roughly 1:28 scale. And the cold model is equipped with 3D-printed nozzles arranged in the four corners. Moreover, the corresponding cases are conducted by cold-state numerical simulation in the cold model furnace, and hot-state numerical simulation in the original furnace. The results show that the experimental data are in general agreement with simulated results in the cold modeling furnace. And through comparison of velocity profile at the same dimensionless furnace height, the results of cold-state model show the similar characteristics of gas velocity distribution that presented in the hot-state situation of the original furnace. Thus, through reasonable cold-state modeling, a detailed velocity distribution can be obtained to give a good insight into the gas velocity deviation characteristics in the horizontal flue.