By Ivan Amato

Machines that create products directly from digital files can save hours of painstaking human labor, compress production schedules, and eliminate costly overstock.

A boundary line of manufacturing history cuts across the factory floor of Siemens Hearing Instruments in Piscataway, NJ. On one side, skilled technicians use casting techniques, precision tools, and years of experience to craft the acrylic shells of hearing aids modeled from silicone impressions of actual ear canals.

On the other side of the factory floor, two pizza-oven-sized machines create similar shells from nylon dust. Inside the machines, needles of laser light, guided by digital design files, robotically scan back and forth, cinching paper-thin layers of dust into tough strata of plastic. Four hours and several hundred laser sweeps later, a batch of 80 hearing-aid shells is completed. The process saves hours of human labor and produces hearing aids that fit and sound better than traditional ones.

It works so well that Siemens, the world's largest maker of hearing aids, is completely switching to the technology at several factories. "This whole process allows us to be more accurate and eliminate human error. This is going to change the business," says William Lesiecki, director of software and e-business solutions for Siemens Hearing Instruments.

Siemens's switchover is just one example of a surging trend in automated manufacturing. Robotics on the factory floor are, of course, nothing new. These days, everything from cars to pharmaceuticals comes off of heavily automated production lines. But direct-manufacturing machines go the next step, using only a digital file--whether created by an engineer or by a scan of a physical object--to custom-make products. They are, in essence, large three-dimensional printers. They both fabricate materials--for example, plastic or metal from powders, or nylon from resin--and shape them into parts. In short, they're a direct bridge between the virtual world of design and the physical world of manufacturing.

The technology is already beginning to displace conventional manufacturing in some areas, like specialized parts for jets. At On Demand Manufacturing, a Boeing subsidiary in Camarillo, CA, 60 complex tubes for the environmental systems inside fighter jets are printed out by machines similar to those at Siemens. Gone are the expensive, specialized molds and dies that these parts previously required. Gone are stringent limits on shape and design, and the months-long waits for custom parts. It's the wave of the future in aerospace, says Miller Adams, a Boeing vice president at the company's Phantom Works R&D organization. "We could have cost savings of 50 percent on specific parts," he says, easily adding up to millions of dollars per year. What's more, printing parts compresses manufacturing schedules by 50 percent as well. "We believe this will work for many industries outside aerospace," Adams adds.

Indeed, Siemens and Boeing are not alone: more and more companies are exploiting direct manufacturing, says computer scientist David A. Bourne, director of the rapid-manufacturing laboratory at the Robotics Institute of Carnegie Mellon University. Bourne says direct manufacturing will eventually become ubiquitous in the manufacturing sector. "I've been talking about this for 15 years, and now it's becoming real," he says. "In five years, it will be on most people's lists of the coolest technologies." Among the business benefits, he notes, will be the dramatic reduction or even elimination of costly overstock. Companies will only have to make products when "someone is standing there with a dollar bill to pay for it," he says. Then, the manufacturer will simply print one out.

For now, the examples of these printout products are somewhat arcane. Beyond hearing aids and jet ducts, they include electrical boxes for race cars, fine-mesh ceramic filters used in making soy sauce, and surfaces that guide air inside jet engines. But evidence of surging interest is unmistakable, says Terry Wohlers, an industry analyst in Fort Collins, CO. The number of machines doing rapid prototyping--a key progenitor of direct manufacturing--is approaching 10,000, and a small but growing percentage of these machines are now being used for direct manufacturing.

Of course, not everything can be made with such machines, and nobody expects them to become as ubiquitous as laser printers: for one thing, the cheapest ones now cost around $30,000 (see "You Want One of Your Own?" sidebar). Direct manufacturing works best for relatively low-volume fabrication of high-cost items. Still, that describes multibillion-dollar markets in arenas as diverse as aerospace, medical devices, and even human bone replacement. "This will be a completely different way of doing things," says mechanical engineer Joseph J. Beaman of the Laboratory for Freeform Fabrication at the University of Texas. "You just push a button."

You Want One of Your Own?

In all likelihood you own a laser printer, which would have been an extravagance 18 years ago. Does this mean a personal fabricator is on its way to your home? You'd scan in something that catches your eye--or download a digital file from the Internet--then hit the "print" button, and your fabricator would bind, glue, and otherwise mold a material into a cell-phone cover, custom-designed fork, action figure, or any number of other digitally definable three-dimensional objects.

Don't hold your breath. Most industry watchers still consider such a scenario a long way off. Earlier this year, no less a player than printer giant Hewlett-Packard floated the concept of a less-than-$1,000 device that could create three-dimensional objects from digital files. More recently, though, the company drew back from the idea. "All I can say is it's one of the things we are looking at. I can't say whether we are still looking at it or have abandoned it," said Dave Berman, an HP spokesman.

Indeed, direct manufacturing's trajectory to homeowner affordability looks long. Prices of industrial machines have dropped quite a bit, but the cheapest still cost $30,000. Even if prices drop below $10,000 in the next decade, predicts Terry Wohlers, an industry analyst in Fort Collins, CO, the most likely buyers of household replicators will be self-employed engineers, who could make prototypes in their home offices, and tinkerers who already have garages full of machine tools. A killer app for the home is hard to foresee. "Most people wouldn't be able to justify a $10,000 or even a $1,000 price tag," Wohlers says.

But for those who did take the plunge, their children might someday pull CDs off of cereal boxes and print out action figures from the latest movie blockbuster. Add the Internet to this scenario, and they'd e-mail handmade presents to friends--or at least to those with their own personal replicators.

--New Scientist