expert voices, 3d printing, LIPSONKURMANEV, environment, green, Melba Kurman, Triple Helix Innovation, Hod Lipson, cornell universityIs Eco-Friendly 3D Printing a Myth? Green Manufacturing

An example of a design project gone haywire. These nearly identical variations of a design in progress were found littering the floor next to a 3D printer in a university lab. It's a good thing that a student could fabricate so many design prototypes in a single night. However, easy access to manufacturing tools might encourage a polluting, "physical debugging" mindset. Credit: Hod Lipson View full size image

Melba Kurman, author, and Hod Lipson, Cornell University associate professor in mechanical and aerospace engineering, are co-authors of "Fabricated: The New World of 3D Printing" (John Wiley & Sons, 2013) and leading voices in the field of 3D printing. They contributed this article to LiveScience's Expert Voices: Op-Ed & Insights as part of their new LiveScience series highlighting issues and developments in 3D-printing technology.

A few years ago, the consensus was happily (and naively) positive that 3D printing was innately greener than conventional manufacturing technologies. The truth is that today, the jury is still out. Society is growing wiser and maybe a bit more skeptical.

Recent research offers the grim estimate that, worldwide, about 2 million deaths each year are caused by air pollution, much of it generated by industrial manufacturing. Manufacturing is generally polluting, no matter how it's done. Ecologically speaking, 3D printing both giveth and taketh away.

Before presenting the bad news about 3D printing's environmental impact, let's talk about the good news: its potential. In the future, additive manufacturing processes like 3D printing will help make manufacturing greener. [How 3D Printers Work (Infographic)]

Compared with traditional manufacturing techniques, the 3D printing process:

– Maintains a strong mass-manufacturing base, but raises product values to high margins and supports skilled labor in biotech, new materials, IT and specialized, high-end manufacturing;

– Has the ability to help designers develop parts and products for optimal performance, which could include reduced weight or longer product lives;

– Makes more efficient use of raw materials: The 3D printing process places raw material only where it's needed (an ability referred to as "net shape manufacturing");

– Reduces the number of parts that need assembly, shortening supply chains; and

– Can fabricate small batches of custom parts at the time of need (reducing inventory maintenance) near the point of purchase or consumption (reducing transportation pollution).

Consuming lots of electrical power

The reality today is that the technology is not there yet. Despite the potential of additive manufacturing to promote cleaner manufacturing, 3D-printing technologies aren't yet eco-friendly. A 3D printer — no matter what sort of raw material it's working with — is an energy hog. [The 10 Best 3D Printers of 2013]

Research at Loughborough University in the United Kingdom (in a study called the Atkins Project) revealed that the 3D-printing process consumes a frightening amount of electrical energy. Researchers compared industrial-grade printers to injection molding machines. They learned that 3D printers that use heat or a laser to melt plastic consumed an estimated 50 to 100 times more electrical energy than injection molding to make an object of the same weight.

A scourge of plastics

Energy consumption during the manufacturing process aside, another not-so-ideal environmental impact of 3D printed manufacturing is its heavy reliance on plastics. Plastic is rarely good news when it comes to the environment, regardless of what sort of manufacturing technique is involved. However, odd as it may sound, injection molding (the traditional method used to manufacture plastic objects) is actually quite clean in that it leaves behind very few unused plastic pieces.

In contrast, industrial-grade-plastic 3D printers that use powdered or molten polymers leave behind a substantial amount of unused raw material in the print bed. Plastic byproduct left behind in a print job can sometimes be reused, but more typically, its material properties are corrupted and therefore no longer suitable. A glimmer of hope is offered by a corn-based printing plastic called PLA that's biodegradable (although its biodegrading process takes many years).

Secondhand fumes

It took years to prove that secondhand smoke was hazardous for your health. Recent groundbreaking research led by Brent Stephens suggests that secondhand printing fumes contain toxic byproducts given off when plastic is heated to high temperatures. For years, printing aficionados have remarked on the fact that certain 3D-printing plastics give off a nice, cozy smell, similar to burning corn kernels. To see whether the burning plastic smell was harmful to living things, Steele measured the air quality inside an air-conditioned office where five desktop 3D printers fabricated small plastic objects (using both ABS and PLA plastics) over the course of two and a half hours.

Air quality analysis revealed that 3D printers could be characterized as "high emitters" of what are known as "ultra fine particles," or UFPs. According to a report from the Heath Effects Institute (HFI), in animal and human studies, observed effects of UFPs included "lung function changes, airway inflammation, enhanced allergic responses, vascular thrombogenic effects, altered endothelial function, altered heart rate and heart rate variability, accelerated atherosclerosis, and increased markers of brain inflammation."The good news about the UFPs emitted by the few 3D printers in Steele’s study was their levels were about the same as cooking indoors. The bad news is that more research is needed on what UFPs, exactly, are emitted by home-scale plastic printers and the impact of UFP emissions in industrial-scale 3D printing environments. In the shorter term, it might be wise to not let your child leave the printer running overnight in her bedroom. And if you're printing plastic at home or in your office, open a window and use a fan to keep the air fresh.

Rethinking the product lifecycle

What about the bigger picture? The environmental impact of making products involves several stages beyond the manufacturing process. Every product — no matter whether it's 3D-printed or mass-produced — goes through a product life cycle.

For example, one environmentally devastating stage in a product life cycle is the process of mining  raw material. Another stage that leaves behind a large dirty footprint is the product assembly process. It takes a lot of petroleum-based fuel to ship products to where they're sold. Constructing, heating and cooling retail space takes a heavy toll on the environment as well. The most negative effects come during a product's final act: when it's thrown away.

3D printing might someday encourage a new kind of pollution: rapid garbage generation. Engineers being trained to respect their raw materials are taught "Think twice, cut once." When people get ahold of easy production tools, however, it’s easy to not heed that wise old adage. Like printing draft after draft of a term paper during its painful revision process, designers and tinkerers might find themselves rapidly printing out a series of incremental variations of a design, an environmentally costly process. [Video - 3D Printing: Doodads to Prosthetic Hands]

To unleash 3D printing's potential as a greener manufacturing technology, the key will be to create unique, greener product life cycles. Perhaps one of 3D printing's most promising environmental benefits will be the fact that computer-generated designs help improve a product's form, function, performance and durability. For example, a 3D- printed metal airplane made of computer-designed, lightweight parts would consume less fuel during its lifetime of use.

3D-printed manufacturing could also change the product life cycle by shortening global supply chains, reducing the amount of fuel that's consumed to ship products from place to place. On-the-spot 3D-printed manufacturing would also reduce the environmental costs of maintaining a climate-controlled warehouse to store inventory. Your family doctor could print out a custom hearing aid for you when you need it. Your local car mechanic could print out new parts for your car without having to order them from a supplier far, far away.

'Bursty manufacturing' and renewable energy

Renewable energy is key to greener manufacturing. However, most renewable energy sources today can't yet provide (at a reasonable price) the incessant, reliable stream of power needed to fuel mass-manufacturing operations.

What if small bursts of renewable energy could be applied to small bursts of manufacturing activity? Computer scientists call the transmission of electrical signals of vastly differing sizes "bursty communication." Why not a future in which "bursty energy" would be applied to "bursty 3D-printed manufacturing?"

Despite improvements in storage technologies and smart-energy grids, renewable energy may always be more prone to fits and starts than burning gas or coal. However, a 3D printer is a versatile beast and can turn on a dime, production-wise. A small manufacturing facility of the future could run several 3D printers, each making a wide variety of different products. This facility could be powered with set amounts of stored renewable energy that would fuel scheduled start-and-stop 3D-printed production runs.  Someday, it would be great to see agile 3D-printing facilities that would rapidly adjust fabrication rates to the level of available renewable power, instead of the other way around.

As Earth staggers under the weight of pollution, humanity needs to better balance the health of the environment against a global consumer economy that grows larger each year. Despite its promise as a manufacturing technology, there's nothing innately green about 3D printing. As 3D-printing technologies become more widely used in all industries, the resulting environmental impact will depend on how these emerging technologies are put to use.

Kuman and Lipson's most recent Op-Ed was How 3D Printing Will Transform Chinese Manufacturing. Follow Kurman @melbakurman. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This article was originally published on LiveScience.com.

绿色制造会成为3D打印神话吗？

一个设计项目的例子去失控。正在进行的设计，这些几乎相同的变化，发现乱扔垃圾旁边有3D打印机在大学实验室的地板上。这是一个学生能够制造如此多的设计原型是在一个晚上是一件好事。但是，容易获得的制造工具可能会鼓励污染，“物理调试”的心态。

梅尔巴Kurman，作者和利普森，机械和航空航天工程康奈尔大学副教授，是“捏造：新世界的3D印刷”的合着者（约翰·威利父子，2013年）在3D领域，最主要的声音打印。他们贡献了这篇文章，以生活科学的专家声音：专栏文章与观点作为自己的新生活科学系列突出了3D打印技术问题和发展的一部分。

几年前，达成的共识是愉快地（和天真地）积极的，3D打印是天生比传统的制造技术更环保。事实是，在今天，还没有定论。社会是越来越明智，也许有点多持怀疑态度。

最近的研究提供了，在世界范围内，每年约有200万人死于空气污染是造成了严峻的估计，其中大部分是由工业生产产生的。制造业普遍污染，无论它是如何做。从生态学上讲，3D打印既赐夺了去。

在提出关于3D打印对环境的影响的坏消息，让我们来谈谈一个好消息：它的潜力。今后，如3D打印添加剂生产过程将有助于使制造更环保。

与传统的制造技术，三维印刷工艺相比：
- 保持强大的大规模的生产基地，但提高产品价值，以较高的利润率，并且支持熟练工人在生物技术，新材料，信息化，专业化，高端制造业;
- 有帮助设计师开发零部件和产品的最佳性能，其中可能包括降低重量或更长的产品生命的能力;
- 可以更有效地使用原料：三维打印过程将原料只在需要的地方（称为“净成形制造”的能力）;
- 减少零件需要装配，缩短供应链的数目;和
- 可以制作自定义部分小批量的需求（减少库存维护）附近购买或消费（减少运输污染）的点的时间。

消费大量的电力

今天的现实是，这项技术还没有。尽管添加剂制造的潜力，促进清洁生产，三维打印技术还不环保。三维打印机 - 不管什么样的原料，它与工作 - 是一个能耗大户。 [2013十大最佳3D打印机]
研究在英国拉夫堡大学英国（在一个叫做阿特金斯工程研究）显示，3D打印过程中消耗电能的一个可怕的量。研究人员比较了工业级打印机的注塑机。他们了解到，使用热或激光来熔化塑料三维打印机消耗的估计50至100倍的电能比注射成型，使相同的重量的目的。

塑料洪水猛兽
在制造过程中的能源消耗之外，3D的另一个不那么理想的环境影响印刷生产是其对塑料的严重依赖。塑料是罕见的好消息，当涉及到环境，不管是什么样涉及制造技术。然而，奇怪的，因为它听起来，注射成型（用于制造塑料物体的传统方法）其实挺干净的，因为它留下很少使用的塑料件。

与此相反，使用粉末状或熔融聚合物的工业级塑料三维打印机留下未使用的原料在打印床显着量。塑料副产品在打印作业中留下的，有时可以重复使用，但是更典型地，它的材料性能损坏，因此不再合适。一线希望是由玉米为原料的塑料印刷称为中国人民解放军那是可生物降解的（尽管其生物降解过程需要很多年）提供。

二手烟雾
它花了几年证明，二手烟是有害你的健康。最近的开创性研究为首的布伦特·斯蒂芬斯认为，二手印刷烟雾含有有毒副产品放出时，塑料高温加热。多年来，打印爱好者都一再提及一个事实，即某些3D印刷塑料放出一个漂亮，舒适的气味，类似于烧玉米粒。要查看塑料燃烧的气味是否有害生物，斯蒂尔测量的空调的办公室凡五桌面3D打印机制造的塑料小物件内的空气质量（同时使用ABS和PLA塑料）在两个过程半小时。
空气质量分析表明，3D打印机可以被描述为“高发射器”的所谓的“超细颗粒”，或超微粒子。据来自希思影响研究所（HFI），在动物和人类的研究报告，指出超微粒子特效包括“肺功能改变，气道炎症，增强过敏反应，血管血栓形成的作用，改变内皮功能，改变了心脏速率和心脏率可变性，加速动脉粥样硬化，并增加脑部炎症标志物。“在斯蒂尔的研究为数不多的3D打印机发出关于超微粒子，好消息是他们的水平是差不多的烹调室内。坏消息是，需要更多的研究是什么超微粒子，究竟是由家庭规模的塑料打印机和超微粒排放的工业规模的3D打印环境的影响发射。在短期内，它可能是明智的，不要让你的孩子留在打印机在她的卧室里过夜运行。如果你要打印的塑料在家里还是在办公室，打开一个窗口，并使用风扇来保持空气新鲜。

重新思考产品生命周期
那么更大的画面？使得产品对环境的影响涉及超过制造过程的几个阶段。每一个产品 - 无论是3D打印或大规模生产 - 经历了一个产品的生命周期。

例如，在一产品的生命周期一个环境破坏性阶段是开采原料的过程。另一个阶段留下一个大的脏脚印是产品装配过程。这需要大量的石油为基础的燃料的船舶产品，他们正在销售。建设，加热和冷却的零售空间，需要对环境产生了沉重的代价也是如此。来在产品的最终法案的最负面的影响：当它扔掉。

3D打印有一天会鼓励一种新的污染：快速的垃圾产生。正在接受培训的工程师，尊重他们的原材料被教导“三思而后行，切割一次。”当人们得到阿霍德容易生产工具，但是，它很容易不小心，聪明的老格言。如同在其痛苦的修订过程中，设计人员和能工巧匠学期论文的草稿之后，草稿打印可能会发现自己很快打印出一系列的设计，环保代价高昂的过程的增量变化。

为了发挥3D打印的潜力，更环保的制造技术，关键是要创造独特的，更环保的产品生命周期。也许3D打印的最有前途的环境效益之一将是一个事实，即计算机生成的设计有助于提高产品的外形，功能，性能和耐用性。例如，一个3D-印制金属飞机由计算机设计的，轻质部件将利用它的寿命期间消耗更少的燃料。

3D打印制造也可以通过缩短全球供应链，减少燃料的消耗真实船舶产品从地方到另一个地方的量改变产品的生命周期。在现场3D打印制造也将减少维持一个气候控制的仓库存储库存的环境成本。您的家庭医生，可以打印出定制助听器时，你需要它。您当地的汽车修理工可以打印出你的车新部件，而不必从一个供应商订购他们很远很远。

“突发制造'和可再生能源
可再生能源是关键，更环保的生产。然而，大多数可再生能源目前尚无法提供（价格合理）不绝，燃料大规模生产业务所需的电力可靠的数据流。

如果可再生能源的小的脉冲串可以适用于制造活性的小的脉冲串？计算机科学家称之为千差万别不同大小的电信号传输“突发性的沟通。”何不在未来，“突发能量”将适用于“突发三维印刷制造？”
尽管改进存储技术和智能电网的能源，可再生能源可能总是更容易产生忽冷忽热比烧气或煤。然而，3D打印机是一种多用途的野兽，可以打开一毛钱，生产明智的。未来有可能运行几个3D打印机的小型制造工厂，每个制作各种不同的产品。这个设施可以供电与存储的可再生能源，将燃料计划的开始和停止三维印刷生产运行集量。有一天，这将是非常高兴看到灵活的3D打印设备，将迅速调整生产速度，以提供可再生能源电力的水平，而不是周围的其他方法。

作为地球污染的重压下蹒跚，人类需要更好地平衡环境的健康对全球消费的经济增长是每年大。尽管它作为制造技术的承诺，没有什么天生的绿色有关3D打印。随着3D打印技术的日益广泛地应用于各个行业，产生的环境影响将取决于这些新兴技术的投入使用。

Kuman和李碧菁的最新专栏文章是如何3D打印将改变中国制造。按照Kurman @melbakurman。表达的观点属于作者本人，并不一定反映出版者的看法。这篇文章最初发表于LiveScience.com。