3-D printing gets real

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.

A Carbon3D printer resembles a hot water heater with the middle section missing. On a shelf at waist height sits a tray of liquid resin. 

Through a photochemical pro-cess, incoming light hardens the resin as it takes the shape of a component. Oxygen prevents it from sticking to the tray. A component rises out of the resin pool in one piece, rather than requiring multiple layers of material. 

"Since you get rid of the layers, you get a higher-quality part," says Kirk Phelps, Carbon3D's vice president of product management. "You get a product that is very strong, heat resistant and flexible." 

Last year, Carbon3D leased its printers to a group of early adopters for $40,000 a year per machine. One of those customers is Delphi, which now wants to find out whether 3-D printing is a practical technique for producing electrical components. 

Jerry Rhinehart, Delphi's manager of additive manufacturing development, says he will install a batch of 3-D-printed connectors and other electrical components in a 25-car fleet this June for road tests. 

Low cost is not the technology's value proposition. For most mass-produced components, 3-D printers will not be competitive with injection molds, Rhinehart notes. 

But if a subassembly of four or five pieces can be replaced by a single 3-D-printed component, manufacturers can cut cost, reduce weight and simplify assembly, he says. 

"You can make it smaller, lighter and simpler," Rhinehart says. "Now you have complete design freedom. That's a wonderful business model for this technology." 

The emerging science also has implications for the aftermarket and service parts business. 

Since 3-D printing is best suited for production runs of 50,000 units or less, it may find a niche in making parts that have low demand -- for instance, for a trim part on a 12-year-old vehicle. A parts retailer such as Pep Boys could maintain its own printers to spit out replacement parts as customers order them, rather than requiring factories to build them and warehouses to store them. 

"Why keep parts in a warehouse for 10 or 20 years when you can maintain a digital CAD file instead?" Rhinehart says. 

The technology's aftermarket potential got a publicity boost in 2014 when astronauts at the International Space Station printed a 4-inch-long ratchet wrench they needed, made from 104 layers of plastic. 

The backroom shop at Pep Boys might not be that glamorous, but that's where this technology may find a home, says Thomas Kurfess, a mechanical engineering professor at the Georgia Institute of Technology and a member of the American Society of Mechanical Engineers. 

"Pep Boys could download a digital file from General Motors and print it," Kurfess says. "So GM doesn't have to worry about inventories or the tooling to produce it. They could get a tremendous increase on their profit margins."