Discrete-Element Simulation of Powder Spreading Process in Binder Jetting, and the Effects of Powder Size
Discrete-Element Simulation of Powder Spreading Process in Binder Jetting, and the Effects of Powder Size
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DOI：
10.1115/msec2021-63351
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
Ana Paula Clares;G. Manogharan
中科院分区：
文献类型：
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作者：
Ana Paula Clares;G. Manogharan
粘合剂喷射在增材制造（AM）技术中获得了特别的兴趣，因为其广泛的应用、更广泛的可行材料系统以及不存在其他AM工艺中存在的快速熔融-固化问题。了解和优化粉末喷涂过程中的打印参数对于提高最终零件的质量至关重要。在这项研究中，离散元法（DEM）模拟，以评估粉末堆积密度，流动性和孔隙率在粉末铺展过程中，利用三个不同的粉末组。两组样品的粒径分布为75-84 μm和100-109 μm，第三组样品的粒径分布为50 μm + 100 μm。采用陶瓷铸造用砂，对粘结剂喷射工艺中粉末散布过程中粉末粒度分布的影响进行了深入研究。据观察，较粗的颗粒比较细的颗粒导致更高的流动性（休止角降低62%），这是由于后者中存在的内聚效应。双峰粒度分布在粉末床中产生最高的堆积密度（增加8%）和最低的孔隙率（减少12%），因为较细的颗粒填充在较粗的颗粒之间产生的空隙中。本研究结果可直接应用于喷射粘结剂AM工艺，也为AM粉末制造商提供了新的见解。
Binder Jetting has gained particular interest amongst Additive Manufacturing (AM) techniques because of its wide range of applications, broader feasible material systems, and absence of rapid melting-solidification issues present in other AM processes. Understanding and optimizing printing parameters during the powder spreading process is essential to improve the quality of the final part. In this study, a Discrete Element Method (DEM) simulation is employed to evaluate the powder packing density, flowability, and porosity during powder spreading process utilizing three different powder groups. Two groups are formed with monoidal size distributions (75–84 μm and 100–109 μm), and the third one consisting of a bimodal distribution (50 μm + 100 μm). A thorough investigation into the effects of powder size distribution during the powder spreading step in a binder jetting process is conducted using ceramic foundry sand. It was observed that coarser particles result in higher flowability (62% decrease in repose angle) than finer ones due to the cohesion effect present in the latter. A bimodal size distribution yields the highest packing density (8% increase) and lowest porosity (∼12% reduction) in the powder bed, as the finer particles fill in the voids created between the coarser ones. Findings from this study are directly applicable to binder-jetting AM process, and also offer new insights for AM powder manufacturers.