The U.S. military is relying more and more on gear that's older than the soldiers who use it, Photonics Spectra notes. Which means the companies that built the hardware -- and originally supplied spare parts -- may be defunct. Blueprints and documentation may be outdated, or have just plain vanished. So reverse-engineering firms, armed with laser scanners, are stepping in, to re-create what was lost."
"Laser scanning systems work by projecting a line of laser light onto a surface," the magazine says. "A camera continuously triangulates the changing distance and profile of the line as it sweeps over the object... [And] a computer translates the video image of the line into 3-D coordinates, providing real-time data renderings."
In other words, think Tron -- the scene where Jeff Bridges gets zapped into the computer -- and you're on the right track.
In the reverse-engineering application, a technician moves the scanner around the object in a manner similar to spray painting. The data is sent to software to convert the point cloud into a surface model that can be imported into computer-aided design software.
The resulting model serves as the basis of a technical data package for the part, and the company sends the package out for bid to contract manufacturers. The winning bidder uses the 3-D model to generate a computerized numerical control program that either produces the finished part or that builds a mold for casting it.
Radian Milparts, out of Willoughby, Ohio, is making new M60 gun mounts for the Navy's H-3 Sea King helicopters. The Navy "had a sample gun mount, but no manufacturing source, and no accurate technical data," the company explains. So Radian scanned the mount, dumped it into the computer, and then produced fresh mounts -- and blueprints -- from the new, electronic design. The effort "follows an earlier, small program where Radian Milparts reinvented, documented and fabricated" an H-3 circuit board.
Wixom, Michigan's Nvision Inc. is using laser scanners at Boeing's Phantom Works, to help maintain the F/A-18 Hornet and the F-15 Eagle -- and to build new planes, like the Joint Strike Fighter.
In this case, it is necessary to compare the physical aircraft to the CAD [computer-aided design] model. An interference problem, for example, may arise when the aircraft is being assembled. In this case, the need arises to compare the physical aircraft to the original CAD design to determine the exact cause of the problem. The complexity of the geometry of state-of-the art aerospace structures makes this a very challenging task. Even when a specific problem doesn't exist, the need often arises to compare the aircraft to the model in order to confirm that the design intent is being met.
