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Lasers Turn Designs Into Solid Objects

New technology expands auto designers' vision and speeds engineering process

A BRIGHT blue dot of light skates across the liquid's surface, tracing faint tracks, like fairies dancing across a pond. But slowly, over a few hours, a solid form begins to take shape.

Automotive stylists and engineers have discovered a way to create something out of virtually nothing. Designs that start out as no more than dots on a computer screen can be transformed into solid objects, thanks to stereo lithography. The technology promises not only to expand a designer's vision, but also to speed up the design and engineering process.

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At the Chrysler Corp.'s Jeep-Truck Engineering (JTE) Center, an engineer peers through a thick glass panel. As the jade-blue laser switches off, a motor hums to life, lifting a basket out of a vat of liquid epoxy. Inside the basket are a dozen small replicas of Chrysler's familiar Pentastar logo. ``If you can conceive it in your mind, we can build it for you,'' boasts Thomas Sorovetz, supervisor of Rapid Prototyping at the JTE Center. Today, most automotive designers and engineers work on computer screens, their drawings and calculations saved as digital data.

Occasionally, though, they find that it is useful to transform that binary information into something they can hold or touch. By conventional means, that data would have to be hand-molded in clay or carefully carved into steel - resulting in a delay of weeks and in costs of tens of thousands of dollars.

Stereo lithography, on the other hand, makes it possible to create a solid rendition almost instantly, and at a fraction of the cost. Engineering data is ``downloaded'' to a special computer that controls the laser. The bright blue beam is then sent skipping across the surface of a transparent epoxy. Whenever it pauses, a tiny dot of resin solidifies. Eventually, these solid dots begin to link together.

``When we started out, it was just a tool for visualization,'' says Bernie Robertson, vice president of the JTE Center, noting that it allowed designers to make models of cars and components. But automotive engineers were quick to discover that stereo lithography could do much more.

In early 1992, Chrysler was hurrying to get its Viper concept car ready for the Indianapolis 500. The Viper was intended as a pace car, but engineers struggled to come up with a working exhaust system. They finally hammered out a design, but fretted that it would take up to 18 weeks to make a working model. They fed the data into the stereo lithography and then, using the epoxy model as a mold, they crafted a one-of-a-kind metal manifold in time for the Viper to do its laps at Indy.

The concept behind stereo lithography was developed in 1980, when it was discovered that certain liquids could be hardened by exposure to ultraviolet light and stacked in layers. A practical method was patented four years later by the firm 3D Systems Inc. of Valencia, Calif. The technology is now being used by all three domestic automakers, as well as aerospace giant Pratt & Whitney and medical firm Baxter Labs. But Richard Fedchenko, vice president of 3D systems, says United States automakers are perhaps the most ``visionary group.''

While Chrysler engineers estimate that they have spent $500,000 on stereo lithography equipment, they figure that they have saved at least $15 million on tooling and modeling costs. And they have made other even bigger savings. One model revealed flaws in the design of a critical component needed for the new Jeep Grand Cherokee. If the defect had not been discovered so early, it might have delayed the product's launch - or forced an expensive and embarrassing recall.

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In some cases, Mr. Sorovetz says, the machines can help accelerate development of individual components by as much as 80 percent. That could provide a critical competitive edge, because automobile manufacturers are striving to trim ``lead time.'' It once took as many as five years to bring a product from concept to production, but most hope to cut that down to about three years.

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