来自Columbia University’s School of Engineeringhave demonstrated a novel Selective Laser Sintering (SLS) 3D printing process which allows multiple powders to be sintered in the same print run.
通过将激光倒入SLS 3D打印机中，以使其向上指向，并用玻璃板代替其粉末床箱，研究人员能够同时用大量材料打印。该团队的新技术使他们能够制造增强的工作原型，其中包含同一层中的两个不同聚合物。随着进一步的开发，可以利用该过程来制造一系列多物质零件，从嵌入式电路板到机器人组件。
“我们的最初结果令人兴奋，”与霍德·利普森（Hod Lipson）一起撰写的约翰·怀特黑德（John Whitehead）说。Whitehead解释了结果：“暗示了可以在按钮的按下可以制造任何零件的未来，其中从简单工具到更复杂的系统（例如机器人）的对象可以从完全形成的打印机中删除，而无需组装。透明
“The limitations of printing in only one material has been haunting the industry and blocking its expansion, preventing it from reaching its full potential.”
多物质SLS生产的局限性
传统上，激光烧结通过使用向下定向激光融合粉末床中的显微镜材料颗粒来起作用。一系列材料与SLS 3D打印过程兼容，包括用于生产持久最终用途零件的热塑性和金属。
尽管激光烧结的灵活性在航空航天和国防行业中有许多应用，但生产方法仍然存在缺点。例如，为了促进粒子烧结，SLS过程需要将完整的粉末床加热到接近熔体的温度。这种环境加热会导致化学和物理变化，从而对物质可预测性产生负面影响，从而导致未加入的颗粒。
Furthermore, unsintered powder supports the part during printing and removes the need for dedicated support structures, it also makes monitoring the process challenging, as the print is hidden with a powder cake. As a consequence, if a build is failing and without in-process monitoring, the flaws may only be discovered at the end of the process.
“In a standard printer, because each of the successive layers placed down are homogeneous, the unfused material obscures your view of the object being printed, until you remove the finished part at the end of the cycle,” explained Whitehead. “This means that a print failure won’t necessarily be found until the print is completed, wasting time and money.”
此外，当前的SLS技术主要允许一次烧结一种材料，从而限制了其制造分级合金和多材料聚合物零件的能力。先前的方法已使用真空用二级粉末代替了未插入的材料，但是交叉污染仍然是该方法的问题。
倒激光烧结3D打印
As a result, the researchers devised a novel 3D printing technique that they’ve dubbed Inverted Laser Sintering (ILS). The new method sinters a material’s particles together by directing the printer’s laser vertically upwards into a thin layer of powder through a borosilicate glass pane.
ILS从沉积在玻璃上的受控聚合物粉末开始。然后将底物压在未连续的粉末单层顶部，因为蓝色激光器用于选择性地融合颗粒物材料。一旦过程完成并提起底物，就可以补充材料。然后重复该过程，不断将新层融合在一起，直到创建3D对象。
使用几个玻璃板可以使用多种不同的粉末，从而可以生产分级和多物质零件。更重要的是，烧结粉末可以分别防止它们混合在一起，就像传统的粉末床方法一样。尽管在团队测试期间未实施清洁过程，但也可以将其集成到ILS中。通过在多个打印床之间运输印刷零件，可以在打印中的停顿之间去除松散的粉末。
Future applications of the new SLS method
为了测试他们的新生产方法，研究团队使用enterit白色TPU和Sintratec PA12热塑性材料的混合物创建了50层厚的2.18mm样品。该部分的平均层厚度约为71μm，比使用常规SLS 3D打印的部分表现出更均匀的厚度。更重要的是，其各个层的高度为43.6μm，将结构很好地放置在常见激光烧结印刷品的标准范围内。
As a result, the researchers concluded that the feasibility of their process and its capability to make stronger, denser materials had been proven. In the future, the Columbia team aims to design an improved printer setup for ILS, with automatic powder deposition and optimized laser parameters, in addition to experimenting with a wider range of materials. With additional research, Hod Lipson, the co-researcher on the project, believes that the method could eventually be applied to produce a variety of multi-material components.
Lipson说：“这项技术有可能打印嵌入式电路，机电组件，甚至机器人组件。”“我们认为，这将通过实现复杂的多物质零件而无需组装来扩大激光烧结，从而将激光烧结到更广泛的行业。换句话说，这可能是将添加剂制造业从仅印刷被动统一零件而转向打印主动集成系统的关键。”雷电竞充值
推进SLS添加剂制造雷电竞充值
近年来，许多增材制造公司雷电竞充值采取了自己的方法来优化SLS打印。这些3D打印雷电竞app下载机通常与常规的SLS机器相似，因为它们从底部融合了粉末，但它们还具有增强的监视功能和材料兼容性。
One current option comes from 3D printer manufacturerAerosint和他们的multi-powder SLS printing alternative该公司的方法被称为“选择性粉末沉积”。该公司的方法由粉末分配器和图案鼓组成，该鼓选择性地以逐条方式沉积细粉。该技术可用于制造多金属3D打印零件。
German 3D printer OEMEOS, has built on decades of data to understand build chamber metrology and develop its patentedEostatein-process monitoringsuite. The technology uses an integrated camera to take a picture of the build area during printing and identifies any irregularities after each layer is formed. Using the captured images, uneven or incomplete layers can be quickly identified, enabling users to stop the process and rectify any issues.
Elsewhere, Swedish startupWematter，启动了其新的SLS 3D打印机重力2020去年11月。该系统已准备就绪，可以对其内置传感器和电子设备进行监视和过程控制。利用其集成相机（提供实时视频提要），用户可以跟踪实时打印的层数。
The researchers’ findings are detailed in their paper titled “倒多物质激光烧结，”发表在《增材制造杂志》上。雷电竞充值该纸是由约翰·怀特海（John Whitehead）和霍德·利普森（Hod Lipson）合着的。
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Featured image shows the research duo’s ILS 3D printing technique which allows more than one powder to be used in the construction of a part. Photo via Columbia University.
