Soldiers in medieval times would wage war attended by a retinue of blacksmiths. Their job: to iron out the dents and dings in their bronze-plated armor and repair their weapons.
Now the U.S. Army is updating that concept with a mobile factory that can roll, fly, or float into battle. But instead of anvil, hammer, and tongs, the Army's factory-to-go uses cutting-edge computerized tools to fuse powdered metals into solid replacement parts for disabled weapons and broken vehicles. The tools can even analyze and fabricate components no longer being made.
The Army has spent more than two years and $16 million to create these futuristic, smart-manufacturing platforms known as Mobile Parts Hospitals. The task of putting together the MPHs was assigned to the Army's National Automotive Center and its partner, Focus:HOPE, a training center specializing in advanced machining technologies. To speed MPH development while holding down costs, the Detroit-area team has focused on testing, shrinking, and toughening up commercial machine tools selected for their versatility.
The real inspiration for MPHs, however, isn't machinery, but medicine. It's the Mobile Army Surgical Hospital (MASH) units featured in Robert Altman's 1970 film. Such units revolutionized wound treatment in the 1950s, and the MPH is poised to do the same for battlefield repair. The latest prototype, built earlier this year, occupies a 20-ft. long container--narrow enough to fit in a standard C-130 military transport plane. "The goal is to be able to deploy anywhere in the world in short order," says Coryne Forest, a civilian manager of the MPH program.
High-speed computer modeling and rapid prototyping are the key technologies in MPH. Suppose, for example, a soldier shows up with a snapped tie-rod, a steel part used to connect vehicle components. A technician checks to see if digital blueprints for the rod are available, either on board or by satellite-link from a U.S. maintenance center. If not, he sets about reengineering the broken rod. First, he uses a 3-D laser scanner to create a software model of the part. In about an hour, the tool, made by Israel's Nextec Ltd., generates a "cloud" of spatial data points that define the tie-rod's shape. Computer-aided design software then stitches this network into a virtual model accurate to a few microns.
Next, the tie-rod data are fed to a machine called a laser engineered net-shaping (LENS) tool, made by Albuquerque's Optomec Inc. By depositing a fine path of powdered metal, it traces a cross section of the part-in-progress. Trailing behind is a computer-controlled laser that fuses and hardens the metal particles. Layer by layer, more material is fused into place, so that--at a rate of about one cubic inch of material per hour--a new part emerges from the smoke and dust. Once the rough spots are ground off by a robotic milling machine, the part is ready to go. While the tools aren't new, the labs' compactness and mobility is novel and significant, says George Fadel, a mechanical engineering expert at Clemson University in Clemson, S.C.
There are some limits. For one, the LENS machine can't yet mix materials in one component. Also, the parts fabricated so far have been no bigger than one cubic foot. And it takes about six hours of processing to make an object that size.
But that's far better than the weeks or months required to fetch a part from the U.S. What's more, the MPH promises to solve one of the military's trickiest repair problems: how to replace discontinued parts. "Our legacy fleet includes heavy vehicles first made as far back as the '40s," says Forest. "Sometimes, the original manufacturer no longer exists." And some older gear is made with materials such as uranium that is now blacklisted because of toxicity. In such cases, the do-it-yourself approach of the MPH may be the only way out of a rut.
To support the MPHs, the Army is considering some ambitious backup infrastructure. It's developing the first of three planned agile manufacturing centers that will be able to whip up replacement parts too big or complex for the MPHs. By 2007, these centers could be connected by satellite to a fleet of MPH units in the field, allowing specialists to help the MPH crews diagnose tough problems.
If the Army can make it work, this on-demand manufacturing model could someday show up in extreme commercial environments as well. "Think of an offshore oil rig, a mine--or even space travel," says Forest. Until then, though, the real action will be on the front lines.
By Adam Aston in New York