MIT Technology Review

Monday, May 9, 2011

GE and EADS to Print Parts for Airplanes

The technology could be used to make parts that perform better and cost less.

GE is starting a new lab at its global research headquarters in Niskayuna, New York, that's devoted to turning three-dimensional printing technology into a viable means of manufacturing functional parts for a range of its businesses, including those involving health care and aerospace. The company aims to take advantage of the technology's potential to make parts that are lighter, perform better, and cost less than parts made with conventional manufacturing techniques.

Technology for printing three-dimensional objects has existed for decades, but its applications have been largely limited to novelty items and specialized custom fabrication, such as the making of personalized prosthetics. But  the technology has now improved to the point that these printers can make intricate objects out of durable materials , including ceramics and metals such as titanium and aluminum,  with resolution on the scale of tens of micrometers.

As a result, companies such as GE and the European defense and aerospace giant EADS are working to apply it in situations more akin to conventional manufacturing, where large numbers of the same part are needed.

GE's first application of the technology could be ultrasound machines that are cheaper and perform better than current versions. One of the most expensive parts of an ultrasound machine is the device that transforms electronic signals into sound and back again—the part that's pressed against a person's skin during an ultrasound. These transducers are made up of thousands of tiny columns spaced just 30 to 40 micrometers apart, with each column being extremely thin, about eight to 10 times taller than they are wide. It's extremely difficult to make such parts using casting, since it's hard to free the part from the mold. So GE makes them using a precise cutting tool that very slowly carves away at a chunk of ceramic. The process is slow and expensive and can only be used to make a limited range of shapes.

Now GE has developed a new printing technology that spreads out a thin layer of a slurry composed of ceramic embedded in a polymer precursor. When a pattern of ultraviolet light is projected on this layer, the material solidifies only where it's been exposed to the light. Another layer of slurry is spread out on top of this and flashed with light, and the structure is built up in this way, layer by layer.

The process is still not ready for mass production, says Prabhjot Singh, a mechanical engineer and project manager at GE Research. But because the process is faster and saves material, "it could achieve orders of magnitude reduction in cost," he says. GE designers using the new process could improve the performance of the transducer because they won't be as constrained in the types of shapes they can make. This could lead to higher resolution ultrasounds.

GE is also investigating the possibility of printing some airplane parts, a strategy EADS  has also recently pursued. At the EADS labs in Filton, U.K., researchers demonstrated that they can print out several different metal parts for airplanes with a technology that uses a laser to heat  metal powders until they form solid metal shapes. Using this technique, EADS has printed metal hinges for engine covers: the hinges allow the covers to swing open for engine maintenance. The parts have intricate  shapes that maintain strength while cutting the weight of the part in half. The new hinge has been put through the tests used for conventional parts and shown to meet performance requirements.  Weight savings are critical in the aerospace industry. According to EADS, reducing the weight of an airplane by just one kilogram can result in fuel savings of $3,000 per year, or $100,000 over 30 years—the typical life of an airplane.

To be sure, the technology is still limited. Although many functional metal alloys can be printed, the high-performance ones used inside an engine can't yet be produced in this fashion (such parts require a level of precise control over the temperatures of the materials during processing that can't be achieved yet in printing). GE will use the new technology to print out engine parts—such as turbine blades—but only for testing certain properties of a design, such as its aerodynamics, and not its ability to survive high temperatures and pressures. Singh says that this could help speed up the design process by making it possible to have a high-precision part built in weeks rather than months.

The other main limitation of the technology is the size of the objects it can print. Depending on the material and the printer, it's possible to print things that are a few centimeters across to at most something near a meter. Printing out wings or parts for some of GE's large power-plant turbines is still not possible. And there are some things that likely will never be made using three-dimensional printing. "It will never be used to make something such as nails. But eventually it could be used to make the tools that make nails," says Jonathan Meyer, a research team leader at EADS Innovation Works.