3D Printing Finds a Custom Foothold in Manufacturing, Part 2

Innovations in speed and compounds

Published: Tuesday, June 26, 2018 - 12:03

This story was originally published by Knowable Magazine.
Part one looked at the innovative possibilities inherent in 3D printing; here we consider some of its shortcomings and the solutions that companies are finding.

A few years into this century, the industry reached a tipping point, as sales of all kinds of 3D fabricators and raw materials began to accelerate substantially. One impetus was simply the passage of time: Because U.S. patents generally last for only 20 years, the ones granted during that first flurry of 3D printing during the 1980s were beginning to expire.

This had a particularly strong impact on the low-end hobbyist market, which was (and is) almost entirely based on fused deposition modeling—Scott Crump’s glue-gun extrusion technique. The raw materials were inexpensive and nontoxic, and the fabricators were safe to use in the home or office. So after Crump’s basic patent expired in 2009, copycats were quick to jump in, the price of the machines fell from more than $10,000 to under $1,000, and they became common sights in “makerspaces” and even schools. “I once counted about 50 companies marketing low-end 3D printers,” says University of Texas materials engineer David Bourell.

Another key factor was that laser sintering of metal parts had finally emerged from the laboratory, after years of efforts by Bourell and others to eliminate voids and weaknesses in the fused powder grains. EOS announced the first commercial metal fabricator in 2004, and continues to dominate this sector. “The metals machines offered a way to manufacture complex parts and achieve mechanical properties very similar to those from traditional methods,” says Rapid Prototyping Center’s Timothy Gornet. And this, he says, “really triggered the thought that additive manufacturing may be able to grow dramatically”—that 3D printing could move out of its niche markets and begin to challenge traditional technologies on their own turf.

For that to happen, however, researchers would have to overcome 3D printing’s biggest shortcomings, starting with its painful slowness. “It would take two days to make a coffee cup,” using standard laser sintering, says UPS’s Alan Amling.

That slowness automatically puts additive manufacturing at a severe economic disadvantage, says John Dulchinos, vice president for global automation at Jabil, an international “contract manufacturing” company that does much of the actual production for brand-name firms such as HP. For most products, says Dulchinos, manufacturers typically do production runs numbering in the hundreds of thousands. But today, he says, “3D is competitive only at tens of thousands.” And even that is only when the parts are intricately shaped and small. When you’re building things up point by point, notes Bourell, “if a part is twice as big, it takes eight times longer.” All of which is why researchers in industry and academia alike have been making speed a top priority.

One notable effort is HP’s first foray into 3D printing, which has drawn a lot of attention because the company is already a major player, not just another startup. The company’s “Multi Jet Fusion” fabricator first lays down a thin layer of powdered polymer in much the same way as a laser sintering system. But instead of tracing the cross-section of the part with a laser, it prints the cross-section with microscopic drops of infrared-sensitive ink. “The print heads are the same as those we use in our industrial inkjet printers,” says Paul Benning, HP’s chief technologist for 3D printing. Then it follows up with a flash of heat that is absorbed by the ink, which fuses the powder underneath. Finally, the cycle repeats with a new layer.

This all happens very quickly, making HP’s machine about 10 times faster and substantially cheaper than an equivalent laser sintering system. “HP is pretty good at inkjets,” notes Bourell. That said, the first model is limited to plastic parts; the company has announced that metal fabricators are coming, but not until later in 2018.

And by that point, HP may well have company: Desktop Metal, a startup based in Burlington, Massachusetts, has announced that it will soon be coming out with a high-speed metal fabricator that will work in somewhat the same way as HP’s. (Instead of ink, it sprays each layer with a binder that holds the powder together until the whole part can be fused in a separate heater.) “Our study concluded that you can do well over 500 parts in a day, while with lasers you could do 12 in a day,” says Desktop Metal’s chief technology officer, Jonah Meyerberg. The company’s machines can also use a wider (and cheaper) range of metal powders, he says, since the material doesn’t have to be optimized for laser melting.

In Redwood City, California, meanwhile, Carbon Inc. has achieved dramatic speed-ups in stereolithography. Carbon founder and president Joseph DeSimone credits several key innovations. The first, developed in his lab at the University of North Carolina, Chapel Hill, is a technique that exposes the working liquid to ultraviolet light and oxygen simultaneously. The resulting chemical interplay, dubbed continuous liquid interface production, “allows us to go really fast” in printing an object, says DeSimone—up to 100 times faster than conventional stereolithography. That’s one reason Adidas is using the company’s fabricators to make its Futurecraft 4D midsoles.

The second innovation is that the working liquid isn’t just a single photosensitive resin, but a mix of several compounds. “Only about 10 to 15 percent of the volume is light sensitive,” says DeSimone, and is there simply to set the shape of the part. The other components are chemicals that will react to form a strong polymer once the fully shaped part is sent to a baking oven. “It’s like epoxy glue, where you get the bond when you react two liquids,” he says. This mixing approach also allows the company to produce a much wider range of materials than was possible with earlier stereolithography systems.

Expanding the range of available materials is, in fact, another key challenge for everyone in the field. EOS, for example, is taking a comparatively incremental approach to increased speed—mainly by improving the fabricators’ powder-handling, and having two, four, or even eight lasers working in parallel. But the company has a whole subsidiary, Advanced Laser Materials (ALM), working to improve the stuff that goes under the laser.

This is especially difficult when it comes to polymers, says ALM president Donnie Vanelli. Within the laser sintering sector, he says, “80 to 90 percent of what’s moved to date has been built on nylon.” That’s because nylon is one of the few polymers that can be not only ground into a powder that rolls out nicely in the machine, but also melts well under the laser. Advanced Laser Materials has been able to make nylon harder, stiffer, lighter, and stronger with fillers such as carbon fiber, tiny glass spheres, and even aluminum granules. “But nylon is not what people typically build parts out of,” says Vanelli. “So, if we really want to expand the future in additive, we have to be able to tell engineers, ‘We can do the materials you’re familiar with.’” There’s been some progress. In November 2017, for example, EOS and sportswear maker Under Armour announced a partnership to develop running shoes with soles made by laser-sintering a flexible polyurethane that’s very common in footwear.

The fundamental challenge

For everyone in additive manufacturing, however, easily the biggest challenge is what EOS’s Glynn Fletcher calls “the habits of the present.”

His office is in Michigan, explains Fletcher, surrounded by factories supplying parts to the automotive industry. “They’re making things in the traditional way,” he says. “They are comfortable with that. And they are not going to overnight throw all that equipment in the dumpster and go to additive manufacturing.”

On the other hand, he says, when you talk to engineers about the advantages of additive—the nonexistent retooling costs, say, or the freedom to design parts for function instead of for manufacturability—“everybody gets that.” So he thinks it’s a matter of when people make the jump, not if.

Certainly it’s the case that EOS, like HP and most other players in the additive manufacturing field, finds itself hosting a growing stream of potential customers who are intrigued by the possibilities—and daunted by the learning curve. “This is a technology that’s very disruptive to process engineering and design,” says EOS marketing director Patrick Boyd. “Potential customers come to us and ask, ‘How do we even start?’” By 2016, he says, EOS was hearing that question so frequently that it launched Additive Minds: a dedicated training division with 100 instructors in five centers worldwide. “It’s Additive Minds’ job to tell people about how to select applications, who needs to be trained, and where are the early adopters succeeding,” says Boyd.

It seems to be working. In one quarter of 2017, he says, the company sold more than it did in all of 2016. Indeed, the potential looks strong for additive manufacturing across the board.

“We’re at the middle of the beginning,” says Boyd, “and it’s going to ramp up very quickly.”

This article originally appeared May 2, 2018, in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

About The Authors

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.

Knowable Magazine

Knowable Magazine is an independent journalistic endeavor from Annual Reviews, a nonprofit publisher dedicated to synthesizing and integrating knowledge for the progress of science and the benefit of society. Sign up for Knowable Magazine’s newsletter.