Editor's note: Thomas Kurfess is a member of the American Society of Mechanical Engineers. His affiliation was incorrect in earlier versions of this story.
It seemed like a cute stunt two years ago when a little-known startup called Local Motors took to the streets of Las Vegas with a car built largely of parts made with a 3-D printer.
But cute no more.
The auto industry is beginning to take 3-D-printed car parts seriously. 3-D printers, once little more than handy tools for quickly creating a one-off prototype part, are emerging as a practical alternative for low-volume automotive production.
Carbon3D, a startup in Redwood City, Calif., is supplying production parts made from polymers to BMW AG and Ford Motor Co. Mini models use a 3-D-printed decorative side scuttle, while the Ford Transit Connect has been fitted with damping bumper parts.
Carbon3D now is working with Delphi Automotive to line up more customers. Others are jumping into the technology.
In September, Alcoa invested $60 million in its Pittsburgh r&d center to develop 3-D printers that could form components from aluminum, titanium and other alloys.
Meanwhile, General Electric has begun using 3-D printers to manufacture fuel nozzles out of powdered metals for jet engines.
The emerging practice -- also called additive manufacturing -- has enormous implications for the auto business. Manufacturers spend huge amounts to tool up assembly lines to make auto parts. Tools and dies must be created to produce early prototypes of parts, often repeatedly as engineers try to get new parts to meet design specs.
Suppliers and automakers now believe they can sidestep some of that investment and time-consuming effort by using advanced printers that build finished parts to spec by building them up from digital designs.
The technology "has definitely advanced a lot over the last several years," says Deb Holton, director of industry strategy for the Society of Manufacturing Engineers. "That's their dream -- to make parts without using a mold."
Carbon3D hopes to supplant traditional injection molds on low-volume production runs of 50,000 units a year or less.
Until now, skepticism about 3-D printing has had less to do with the basic science than with the practicality of relying on it on unforgiving factory schedules.
Printers have been slow until now. They could work with just a few raw materials. And the durability of the objects produced was minimal. The layered component could crumble under the stress of everyday use, so they primarily were used for protoypes or display.
But the technology has evolved and is creeping into other industries, such as aerospace and medical products.
The printers used for commercial purposes by Carbon3D, for example, are up to 100 times faster than previous-generation printers. They can turn out objects in a variety of raw materials. And more important, their parts match the strength of parts produced by injection molds.