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EAST HARTFORD, Conn. — For decades, aerospace manufacturers like Pratt & Whitney have fabricated engine parts by tooling, lathing, milling and forging.

Now, they’re printing.

They’re using
3-D printers, which use lasers to heat granules of plastic or metal to build up three-dimensional parts, layer by layer. The end product could be any solid design, however complex.

Pratt & Whitney and GE Aviation are extending the limits of this technology to make production-run parts for their latest commercial engines. This process is letting manufacturers design components that would have been impossible to mill or forge in yesterday’s aerospace factories, while saving money and, in some cases, making parts lighter.

And for 3-D printing — also called additive manufacturing — the fact that the vanguard technology has passed through the testing fires of a jet engine is a good sign.

Pratt, the engine division of Hartford, Conn.-based United Technologies, put more than two dozen 3-D-printed components on its latest quiet and fuel-efficient PurePower geared turbofan engine, said Thomas Prete, the company’s head of engineering. “We’ve contemplated lots of parts and continue to add to the list.”

Pratt’s main competitor, GE Aviation, is using 3-D printing to make complex fuel nozzles for an engine.

Prete said that Pratt’s designers can now make a single part in one process that otherwise would have been a time-consuming combination of five or 10 pieces that need to be attached and heat-treated before they are ready.

But the main advantage, Prete said, is that engine designers can do things that would have been impossible before.

“What we do now is go directly from design to metal using additive manufacturing so you eliminate an entire process,” Prete said. The process speeds up the company’s engine development as well as saves costs by eliminating the need to mill down new parts every few days.

Prete said that some of the 25 parts are simple, such as brackets, and others are more complicated components in the engine’s air pathway.

In November, GE Aviation acquired 3-D printing firm Morris Technologies. Months ago, GE announced that it would be 3-D printing the fuel nozzles on its commercial LEAP engine, being developed with French aircraft manufacturer Snecma. When the parts were manufactured traditionally, they were made of 18 parts fused together. Now they are made as one part and come out 18 percent lighter.

In the next five years, GE plans to invest $3.5 billion in additive manufacturing and 3-D printing.

More than anything, though, the placing of these components into jet engines is just what the advanced manufacturing industry has been waiting for: a serious proving ground that shows that mainstream manufacturers have figured out how to make the materials and the process work, and work in a quality way that makes financial sense.

It’s one thing to print a plastic trinket, and it’s another thing altogether to manufacture a metal component that will hold up under thousands of degrees of temperature, constant stress and years of operation.

“A lot of people talk about additive manufacturing — we call them the hype people — they’re the ones that make a lot of the desk trinkets,” Prete said. “The magic comes from being able to predict accurately the capability of the materials using the additive manufacturing process and being able to confidently put it in a jet engine environment.”