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M. Mitchell Waldrop


3D Printing Finds a Custom Foothold in Manufacturing, Part 1

From rocket thrusters to shoe soles—additive technologies expanding sights

Published: Monday, June 25, 2018 - 12:03

Since May 2015, in a section of its WorldPort distribution center in Louisville, Kentucky, United Parcel Service (UPS) has been operating a spare parts warehouse with no spare parts. Instead, the facility is stocked with ultrafast 3D printers that can build up almost any plastic part that’s required, layer by layer by layer—and have it ready for UPS to deliver anywhere in the United States by morning.

“It was a no-brainer,” says Alan Amling, UPS’s vice president for corporate strategy. Storing spare parts for quick delivery was already a big moneymaker for the company, he says. UPS operates more than a thousand field-stocking locations worldwide—all full of items that somebody might need someday, maybe. The industrial customers who pay for that service have to keep the parts available because of warranty contracts, says Amling. But they hate it. “Inventory storage costs are massive,” he says. “So we started to see 3D printing as a solution.”

Although 3D printing isn’t cost-effective for every part, says Amling, the Louisville microfactory has already been successful enough for UPS to replicate it at several sites around the United States, with plans to eventually take it worldwide. And that’s before the centers add the capacity to print metal parts later in 2018. But what Amling particularly savors is the way 3D printing has blurred the boundaries. When a delivery firm suddenly starts doubling as a manufacturer, he says, you’ve arrived at someplace new—“a white space.”

As part of an effort to supply parts “on demand,” United Parcel Service has partnered with Fast Radius, which can tap an array of additive and traditional methods to custom build metal and plastic parts (shown). CREDIT: UPS

It’s the kind of genre-scrambling that 3D printing is starting to get very good at. The various technologies that fall under that heading have always encompassed much more than the low-cost hobbyist machines most of us know. But in just the past few years, 3D printers have begun to emerge as a serious alternative to standard fabrication techniques like casting, milling, and injection molding. Often called “additive manufacturing” for the way they add material to make a part rather than grinding it away, this suite of 3D technologies is increasingly being seen as a force that could transform the very idea of a factory, in much the same way that personal computers have transformed the rest of the world.

“I think of additive as the democratization of manufacturing,” says Mike Molnar, a manufacturing engineer turned policy director at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. Molnar directs Manufacturing USA (initially called the National Network for Manufacturing Innovation), a series of federally funded laboratories that do research on additive technologies, artificial intelligence, robotics, and other advanced industrial techniques.

As he explains it, 3D printing promises a new era of on-demand, distributed manufacturing that’s as close as possible to the consumer—when it’s not literally in the hands of the consumer. UPS’s Louisville microfactory is an example. So is the 3D printer that NASA installed on the International Space Station in March 2016, so that astronauts can print hard-plastic ratchet wrenches and other parts without having to wait months for the next resupply launch. In neither case does anyone need elaborate assembly lines and machine tools, just digital files.

A part of 3D printing’s appeal is its ability to create tools and parts as needed, in remote locations. Aboard the International Space Station in 2014, NASA astronaut Barry Wilmore displays a ratchet wrench created from a 3D printer a long way from Earth. CREDIT: NASA

But just as important, says Molnar, 3D printing unleashes the creativity of inventors and designers. They can optimize their parts for shape, strength, weight, or whatever else they can imagine, without ever having to worry about whether it’s physically possible to machine, cast, or assemble the things. One example is the SuperDraco thruster developed by the private rocket company SpaceX. The intricately shaped nickel-alloy device isn’t put together in the usual way from dozens of smaller parts. It is 3D-printed as a whole from metal powder fused by a laser. Another example is Adidas’s Futurecraft 4D running shoe line, which features midsoles with a 3D-printed foam structure that is designed for ideal support and minimal weight—and that can be tailored to each customer’s foot and running style.

SpaceX launched its first metal rocket hardware created by 3D printing in 2014. The SuperDraco Thruster, shown here, is made of a high-performance metal alloy and was created using additive manufacturing techniques in less time than traditional machining. The thruster was designed to fire as part of the launch escape system for SpaceX’s piloted Dragon spacecraft.  CREDIT: SpaceX

Granted, says Molnar, “Additive has lots of hype.” In the real world, for example, most additive technologies are much slower than standard fabrication methods like casting or machining, and can work with only a comparative handful of polymers, ceramics, and metal alloys. “But take 90 percent of that hype and throw it away, and the rest is still revolutionary,” adds Molnar.

That prospect is why the Obama Administration made additive technology a top priority when it launched Molnar’s manufacturing research program in 2011. It’s why established companies and startups alike have entered the game, determined to achieve dramatic increases in printing speed. In 2016, for example, HP Inc. (formerly known as Hewlett Packard) introduced a system that can churn out plastic parts 10 times faster than previous 3D printers at half the cost. The machines can even help “print the printer” by making some of the parts required to clone themselves.

And it’s why companies like the German firm EOS, which has been making 3D printers (including the ones used by SpaceX) for nearly three decades, is experiencing a boom in demand. “It took us 20 years to sell our first 1,000 printers,” says Glynn Fletcher, president of EOS’s North American division. “Today we’re gearing up for 1,000 per year.

“Additive manufacturing today is a $5- to $6-billion industry,” continues Fletcher. And while that’s a lot, he says, “It’s only a tiny fraction of 1 percent of the total manufacturing industry.” So with even a little bit of additional market penetration, “Additive has the potential to go from $5 billion to $50 billion in the not too distant future. We have the potential to be very disruptive. We just have to figure out how.”


The idea of 3D printing was definitely in the air by the early 1980s, says Timothy Gornet, who manages the Rapid Prototyping Center at the University of Louisville in Kentucky. “Laser and inkjet 2D printing was advancing rapidly,” Gornet says. “So I believe for engineers it was natural to think, ‘If I can drive a 2D printer from a digital file, why not do that to create a 3D part?’”

In fact, he says, that idea was so compelling that inventors independently found more than half a dozen ways to implement it.

One evening in March 1983, for example, engineer Charles Hull phoned home from the little lab his company let him use nights and weekends. “Come on down here,” Hull told his wife. “You’ve got to see this!”

“It had better be good,” replied his wife, who was already in her pajamas.

It was. Hull’s day job was to make plastic coatings for tabletops: Just brush on a liquid acrylic resin, hit it with ultraviolet light, and the resin would instantly harden into a protective surface. But on his own time, Hull had been trying to add a dimension. His idea was to take a pot of that same resin, illuminate its surface with ultraviolet light in a pattern that would make a portion of the liquid harden into the cross-section of some part, then raise the level of the liquid a tiny bit to form a new layer and repeat. Eventually, he would be able to drain the unhardened liquid to reveal the finished item.

Hull called the process “stereolithography”—a mashup of Greek terms that roughly translates as “3D writing in stone.” What he proudly showed his wife on that March evening was his first successful print job: a small plastic eye cup that he still has. The company Hull co-founded in 1986 to commercialize the technology, 3D Systems of Rock Hill, South Carolina (originally based in Valencia, California), continues to be a major player in the field.

Plastic T. rex toys printed by Carbon using a variant of stereolithography CREDIT: Courtesy of Carbon

Three years later, in Eden Prairie, Minnesota, mechanical engineer Scott Crump carried out an experiment in the family kitchen. He’d been inspired by the way standard plotters move pens around on 2D sheets of paper to make blueprints and architectural drawings. He wanted to do something similar in 3D, using “pens” that built up solid objects by extruding material one layer at a time. And he’d finally figured out a way to demonstrate the idea. Using a handheld hot-glue gun that he’d filled with a mix of polyethylene and candle wax, he systematically built up a toy plastic frog for his 2-year-old daughter.

She loved it. And that positive customer response encouraged Crump to keep experimenting with the technique, which is now called fused deposition modeling. His wife, Lisa, finally exiled him from the kitchen to the garage after everything the family ate started tasting like plastic. But Stratasys, the company that Scott and Lisa Crump founded later in 1989, has gone on to become another major maker of 3D printers.

At the University of Texas in Austin, meanwhile, a mechanical engineering graduate student named Carl Deckard had spent the mid-1980s working out the kinks in a scheme that had obsessed him since his senior year in college. The idea was to lay down a thin layer of powdered plastic—Deckard initially used a large salt shaker—then trace the cross-section of a part with a laser guided by a computer (a heavily modified Commodore 64.) The plastic would melt wherever the laser touched it, fusing with the cross-section below. Then the process would repeat after he added a new layer of powder. At the end, the leftover powder could be vacuumed up for reuse, leaving just the finished part.

Deckard eventually got this laser sintering technique to work well enough to earn his master’s degree in 1986 and his Ph.D. in 1988. The company he cofounded to commercialize it, DTM, was later purchased by 3D Systems—and laser sintering is now one of the go-to techniques for industrial-strength additive manufacturing.

Additive manufacturing allows the creation of intricate designs in a variety of shapes and sizes. Although plastics (right) have been the most well-known products of 3D printers, the last decade has brought progress in making metal parts (left) as a laser sintering process and other methods opened up new vistas for the technology. Challenges remain in speed, materials, and infrastructure. CREDIT: MARINA GRIGORIVNA / SHUTTERSTOCK

During the early years, these 3D printing techniques and the others that soon followed were collectively known as “rapid prototyping,” largely because that was almost the only profitable application. 3D printing turned out to be a very good way to make new device prototypes, which engineers still liked to use for checking fit and function, or for holding in their hands as a communication tool. (“If a picture is worth a thousand words, a part is worth a thousand pictures,” says Gornet.)

The pioneers in the field had plenty of other applications in mind, adds Gornet. “As soon as engineers were able to get prototypes quickly, they immediately started to think how 3D printing could be used” to advance manufacturing customization, on-demand spare parts, and all the rest. But reality too often intervened. Early 3D polymer parts were often quite brittle, for example. They also tended to be expensive, mainly because the printing was so painfully slow that it took days to make even simple parts. And the range of available materials was quite limited, with metal and ceramic parts not yet out of the laboratory, and polymer parts pretty much restricted to nylon.

Still, by the end of the 1990s, researchers had made steady progress on these problems, and 3D printing was beginning to find other profitable niches in applications where the advantages outweighed the time and cost penalties. Orthodonture was an early example: In 1999, the Netherlands-based firm Align Technology introduced Invisalign, first of the removable, clear-plastic inserts that serve as an alternative to conventional wire braces. Because each of the devices had to be custom-fitted to an individual patient’s teeth, Align started 3D-printing them with stereolithography, as did the competitors that followed. This meant that the inserts were roughly twice as expensive as wire braces—the cost of a full set today averages $5,000—but the convenience factor made them a hit anyway. They require fewer orthodontist visits, and can easily be removed for eating and tooth-brushing. The industry is currently printing millions of the inserts per year, each of them customized by a simple change in the printer’s programming.

One of the most commercially successful applications of 3D printing so far has been customized, see-through braces (sold as Invisalign and under other names) made by stereolithography. CREDIT: DAVIS DENTAL / WIKIMEDIA COMMONS

Hearing aids followed a similar path, starting in 2000 when the Swiss company Phonak began using stereolithography to make hearing aids that were customized to fit each patient’s ear canals. Today, the vast majority of in-ear hearing aids are made this way.

Part two looks at some of the challenges and solutions involved in making 3D printing cost-effective for industry.

First published May 2, 2018, in Knowable Magazine.


About The Author

M. Mitchell Waldrop’s picture

M. Mitchell Waldrop

M. Mitchell Waldrop is a freelance writer in Washington, D.C. He is the author of Man-Made Minds,Complexity, and The Dream Machine, and he was formerly an editor at Nature.


Additive- The Wild West of Manufacturing

For all its promise and potential, additive manufacturing is, in fact, the wild west of manufacturing. For several years, the America Makes & ANSI Additive Manufacturing Standardization Collaborative has been working diligently to identify needed industry standards covering additive. The second version of "Standardization Roadmap for Additive Manufacturing" has just been published. It is available at Standardization Roadmap for Additive Manufacturing (Version 2.0)