\”Materials Today\”: a self-supporting vertical printing cylinder array

In recent years, a variety of additive manufacturing technology matures, began to play an important role in the manufacturing sector. Among them, direct ink writing (DIW) due to its simplicity universality, in areas such as tissue engineering and materials attracted wide attention and research. Typically, only the printing ink according to a set path in the X-Y plane formed layer by layer stacked in the Z-direction, this method is most suitable for printing structure. However, for extreme cases (e.g., a columnar array), and if still using the slice layer by layer stacking manner for printing, print resolution is limited by the configuration of the nozzle and the path design, the print structure surface irregularities. 《Materials Today》:垂直打印自支撑柱状阵列 Recently, University of Aveiro in Portugal José MF Ferreira et people affected by a drop on demand (DOD) inkjet printing method inspired, developed (the FOD) method for the first time in the vertical direction based on the 3D-demand print wire directly in ink (the DIW) is supported by the columnar arrays , suitable for printing a variety of ceramic materials and metallic inks, is expected to used in print in many fields of human tissues, organs, and functional devices. Work related to \”3D printing vertically: Direct ink writing free-standing pillar arrays\” in the title, recently published \” Materials Today \” on.

[explain] Photo

Researchers system uses a mechanical motor to print, can achieve rapid extruded downward movement is stopped and lifted upwards, the pneumatic system is difficult to rapidly stop the ink extrusion. In addition to the printing system, the ink is suitable for printing the vertical key. For horizontal print, the ink flowability and viscoelastic are critical and may be assessed by the rheometer. But in the vertical printing process, the ink only needs to have shear thinning characteristics, the need for further extrusion sufficiently rigid to ensure that the column does not collapse, the ink must exhibit thixotropy so that the \”increase in viscosity in a stationary state, and when subjected to a constant shear stress viscosity reduction. \” As shown, the print strut from the syringe 1 is gradually downward movement starts, until the nozzle reaches the printing position setting byQuantitative piston ink deposited extruded column, while the syringe at a predetermined rate is increased, the extrudate is stretched to the maximum stress of ink; print height after arrival, the piston stops moving, the syringe is retracted to the initial position quickly, the set height Print pillar is formed. Repeating the above printing step can print height-adjustable periodic or aperiodic columnar array. Effects

《Materials Today》:垂直打印自支撑柱状阵列
Fig 1 a schematic view of print individual strut

Researchers titania strut to print an example, a detailed study of the feed, the feed rate and other factors on the back of the printing architecture, found 1.0 retraction speed feed speed 1.8mm / s and 1.0-3.0mm / s can print the flat surface of the strut, the strut having a good self-supporting, but is slower or faster speed will result in a surface roughness or the occurrence of strut fracture.

《Materials Today》:垂直打印自支撑柱状阵列
Effect of FIG. 2 printing parameters of the printing architecture

Researchers vertical printing method for printing a traditional ceramic (TZ-3YS and titanium dioxide), the functionality of the piezoelectric ceramic and oxide aluminum and other materials, and titanium dioxide to print an example, shows the different height of the columnar arrays of printing, but can also print out a columnar array of a plurality of patterns.

《Materials Today》:垂直打印自支撑柱状阵列
FIG three vertical print more materials

Researchers ink containing titanium dioxide as an example, the effects of printing ink thixotropic structure. It was found that adding a very small amount PEI can greatly increase the elastic modulus of the ink, the ink shortened viscoelastic internet. Thixotropy test results show that, regardless of the original ink at the lower stationary or when shear modulus, is difficult since the printing support; PEI added ink modulus decreased when cut, the modulus of the ink is still rapid rise to more than 60% of the original high, reflecting the good thixotropy, a good print can be vertical columnar array structure.

《Materials Today》:垂直打印自支撑柱状阵列
FIG thixotropic Printing Ink 4

Summary

Researchers using a direct-write manner a columnar array of vertical printing, direct write printing increases the flexibility, no longer limited to the conventional printing XY plane, can be extended to XZ, YZ XYZ even multi-directional printing and the like. This printing methodIt can be used to build complex structures such as veins of the heart, has broad application prospects in the field of tissue engineering, can print a variety of functions such as piezoelectric ceramic materials, and applied to piezoelectric sensors, radiators, Braille and many other areas. Related links: https: //www.sciencedirect.com/science/article/abs/pii/S1369702120300171

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