Injection printing: additive molding via shell material extrusion and filling
Injection printing: additive molding via shell material extrusion and filling
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DOI：
10.1016/j.addma.2020.101469
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发表时间：
2020-12-01
影响因子：
11
通讯作者：
Colon, Austin
中科院分区：
文献类型：
--
作者：
Kazmer, David O.;Colon, Austin
材料挤压是原型制造和数字制造的一种流行工艺，但相对于替代工艺，它在零件强度、特征分辨率和生产率方面缺乏。注射打印解决了这些问题，它结合了零件外表面以精细分辨率的材料挤压和以高流速的更大的内部腔的注射成型。因此，注射打印旨在利用材料挤压打印机的完全熔化能力来减轻困扰增材制造的尺寸诅咒。给出了成形腔内流动以及壳壁应力和挠度的简单控制模型。为了验证注射打印相对于材料挤压的性能，用丙烯腈-丁二烯-苯乙烯（ABS）打印了冲击试样和拉伸棒。对试样的拉伸和冲击结果进行对比，并对试验后试样进行图像分析。研究发现，在相同的线性打印速度下，与传统材料挤出相比，注射打印的打印速度平均提高了3.2倍。在性能方面，与挤压材料相比，注射打印拉伸杆（平面内）的刚度、强度和失效应变分别提高了21%、47%和35%。冲击试样和垂直打印拉伸棒的性能也显示出有希望的进步，尽管与打印机的熔化能力有关。尽管如此，注射打印仍然是一种广泛适用且易于实现的工艺，可以提高零件强度和生产率，同时在不大幅延长打印时间的情况下提高特征分辨率。
Material extrusion is a popular process for both prototyping and digital manufacturing, yet it is lacking in terms of part strength, feature resolution, and production rate relative to alternative processes. Injection printing addresses these issues by combining material extrusion of the outer surfaces of the part at fine resolution with injection molding of larger interior cavities at high flow rates. Injection printing thus aims to utilize the full melting capacity of material extrusion printers to mitigate the curse of dimensionality that plagues additive manufacturing. Simple governing models for flow in the formed cavities as well as the stress and deflection of the shell walls are presented. To validate the performance of injection printing relative to material extrusion, impact specimens and tensile bars were printed of acrylonitrile butadiene styrene (ABS). The tensile and impact results of the samples were compared, and image analysis was performed on the post-test samples. It was found that injection printing increased print speeds by an average factor of 3.2 relative to conventional material extrusion using the same linear print velocities. With respect to properties, the stiffness, strength, and strain to failure of injection printed tensile bars (in-plane) were respectively increased by 21 %, 47 %, and 35 % compared to material extrusion. Properties of impact specimen and vertically printed tensile bars also showed promising gains albeit with constraints related to the printer's melting capacity. Even still, injection printing is shown as a broadly applicable and readily accessible process for increasing part strength and production rate while enabling improved feature resolution without greatly extended print times.