Wednesday, November 04, 2009

Device like ‘Star Trek’ replicator is in the works

Technology uses electron beam to melt metals, build objects layer by layer
Space explorers have yet to get their hands on the replicator of "Star Trek" to create anything they might require. But NASA has developed a technology that could enable lunar colonists to carry out on-site manufacturing on the moon, or allow future astronauts to create critical spare parts during the long trip to Mars.

The method, called electron beam freeform fabrication (EBF3), uses an electron beam to melt metals and build objects layer by layer. Such an approach already promises to cut manufacturing costs for the aerospace industry, and could pioneer development of new materials. It has also thrilled astronauts on the International Space Station by dangling the possibility of designing new tools or objects, researchers said.

"They get up there, and all they have is time and imagination," said Karen Taminger, the materials research engineer heading the project at NASA's Langley Research Center in Virginia.

Taminger's project has undergone microgravity tests aboard NASA's "vomit comet" aircraft. Now she hopes to get EBF3 scheduled for launch to the International Space Station, so that space trials can commence.

Shaping metals at will
EBF3 requires a few crucial components: power for its electron beam, a vacuum environment, and a source of metals. While "Star Trek's" replicator could work without a supply of subatomic particles, reality is a different story.

"It'd be nice if we could build something from nothing, but it doesn't work that way," Taminger told

For EBF3, metal wires continually feed into the tip of an electron beam. The beam melts the wires and applies them carefully on top of a rotating plate to build an object up slowly, layer by layer.

A few similar technologies exist, but EBF3 has several advantages. First, its electron beam requires far less power than comparable devices and produces less radiation compared to more powerful beams. Its dual wire feeders also allow scientists to create mixes of new materials that vary in strength or other properties within the same solid piece.

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"We can change the composition on the fly," Taminger explained. "You can add alloys of different chemistries and then adjust the speed that you feed the wires, and that would change the chemistry of the parts we build."

The flexibility of the manufacturing could also embed fiber optic cables inside a solid piece of metal, either for use in communication or for monitoring stresses within the manufactured part.

Major aerospace manufacturers have already begun running thousands of strength tests with the EBF3 device to see whether it can produce certified parts for engines and airframes, researchers said. They foresee cost savings of up to $1,000 per pound of manufactured parts, compared to the usual forging and machining methods that require a 6,000-pound block of titanium to produce a 300-pound part.

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