Despite recent advances, additive manufacturing (AM) technologies remain too slow for mass-production automotive manufacturing. However, companies use AM extensively in design and engineering, and experts say the technology could revolutionize production by increasing efficiencies for traditional manufacturing methods.
“For Ford, producing the volume of parts that we need to support vehicles, this is one of the bigger areas that will impact the manufacturing world – supporting traditional manufacturing with additive technology,” says Harold Sears, Ford’s additive manufacturing technical expert, effectively the company’s in-house consultant for design and manufacturing engineers.
AM in design
For a company that considers AM technology too slow for automotive production volumes, Ford 3D prints many parts each year. The automaker has five additive factories worldwide, producing about 250,000 components per year – just don’t expect to see any of those on new cars or trucks.
From the tires to the roof, designers and engineers print versions of nearly every component on every car at some point in the product-development process.
“It’s really enabling engineers to do design iterations quickly. You can get a part in hours or days instead of weeks or months with traditional methods,” Sears says. “Traditionally, you would make one test, go back and modify the tooling, make another part, and so on. Today, designers are submitting requests for having multiple versions of a part built at the same time. They can do their testing in parallel.”
Sears explains that Ford uses AM prototypes for fit-and-finish testing and to measure functional performance.
Fit-and-finish – “An engineer will develop the characteristics he needs from a part, and we follow up very quickly with tests for fit and finish – fitting onto its place in the vehicle to test its interaction with components around it,” Sears says.
Typically used for plastic parts, fit-and-finish testing identifies where parts rub against each other, creating squeaks and rattles; where gaps between components are too large, creating spaces for wind noise and potential rain leaks; and aesthetic flaws – combinations of parts that just don’t look right when put together.
Scott Sevcik, head of Aerospace, Defense & Automotive at Stratasys Ltd., says automakers have been using AM for fit-and-finish testing for decades, but there’s still a lot of room to expand its use.
“Our newer polyjet systems can make incredibly detailed parts with lots of colors and textures,” Sevcik says, adding that older technologies were limited to a single material with few surface-finish options. “You can really get a true look and feel of what your final part’s going to look like. The ability to blend in different materials has helped grow capabilities.”
Functional testing – Newer AM systems can print metal parts, something that’s having a huge impact on powertrain testing, Sears says. Creating cast-aluminum or cast-iron engine and transmission parts was traditionally expensive and time consuming. As engineers got close to finishing engine programs, producing more than a handful of prototypes to identify the optimal design could be cost prohibitive.
“Now, with more robust materials and better processes, we’re able to take a lot of these prototypes beyond fit-and-finish testing and go into functional testing – being driven around test tracks, being run inside of dynamometers – functional parts on vehicles and in powertrains,” Sears says.
In some cases, engineers 3D print a metal part for tests. As designs get closer to production, Sears says it gets very important to make sure that the final part is still something that can be manufactured. So, designers use binder-jet printers from ExOne to create sand molds, similar to the molds that will be used for production parts – closely simulating prototype shapes and manufacturing build processes (see ExOne sand-casting sidebar).
Supporting bigger parts
Automotive designers have increasingly consolidated smaller components into bigger parts. Dashboards, for example, used to be produced in three or four pieces and assembled in plants before installation. Today, many car designs have plastic dashboard enclosures that have been injection-molded as a single piece.
Sevcik says larger moldings have fewer welds and connections, creating fewer points of failure and fewer opportunities to introduce squeaks and rattles into vehicles. Eliminating welds, fasteners, and adhesives to bond components together lowers manufacturing costs and reduces weight. Prototyping those massive parts, however, hadn’t been possible.
Sears says Ford engineers used to split CAD files into four or five parts, print each of those, and connect the segments to create large prototypes. Thick weld or glue lines made it hard for designers to evaluate the aesthetics of components, and the parts weren’t perfect representations of production components, so fit-and-finish evaluation was difficult.
“We wanted to support what the designers were already doing – designing some really large pieces that didn’t fit into the build areas of most of our machines,” Sevcik says. The result was the Stratasys Infinite-build 3D printer, a machine that Ford engineers are experimenting with. While it has a defined X- and Y-axis, the machine has an open space in the back for the Z-axis. Theoretically, it could print 100ft-long components (See Stratasys Infinite-build 3D printer sidebar).
“With this equipment, we can print an entire console in one piece – much faster than producing each piece separately and gluing them together,” Sears says.
For now, Ford and Stratasys engineers are collaborating on the prototype machine to perfect build techniques.
“Even something as simple as taking some fasteners or bonding out of the car is another step toward weight-reduction goals, so there’s a real need for better prototypes,” Sevcik says.
While the vast majority of automotive AM work today is in design studios, Sears says he’s especially excited by the role he expects the technology to play in manufacturing plants.
“We’ve done a few applications with very positive results. This is one of the biggest areas 3D printing technology will be able to impact – everything starting with more cost-efficient fixtures, checking devices, to more ergonomically correct tools for workers,” Sears explains.
Sevcik adds something as simple as making tools lighter can have a big impact. Many custom jigs are made from welded steel rods or bolted-together aluminum strips, making them so heavy that plants need to use forklifts to move them into place.
“They’re constrained by what you can machine quickly, so you have a lot of blocky shapes, and it’s really not ideal for what you’re doing,” Sevcik says. Replacing those heavy metal parts with lightweight plastic tools means “they’re easier to move around, easier to work with. You can incorporate a lot of complexity into the design to simplify the manufacturing procedure.”
With one customer, Sevcik says, Stratasys was able to replace a 150 lb metal fixture with a 10 lb plastic one. Employees could carry the new jig to work sites with one hand.
A big advantage for custom-printed fixtures is a lower cost of failure. Because traditional build techniques are time consuming, Sears says once a jig or fixture is in place, it tends to stay in use even if it’s not ideal for the job. The cost of replacing it with something better can be too high.
With a printed tool, Sevcik says getting it wrong isn’t as big of a deal. If the first version of the tool design works but could be a lot better, toolmakers could alter the design, set the printer, and have a new tool in place the next day.
“If there’s an idea to take a little more time off the process by making a small change to the fixture, there’s no 6-week wait time from the tool shop or a $30,000 price tag,” Sevcik says.
“That ability to customize the tool for an operator really applies for automation as well. We have customers who are 3D printing robotic end effectors,” Sevcik adds. For example, one customer 3D printed grippers for pick-and-place robots. “You can make that robot not work as hard if it’s carrying a lighter, more-optimal tool – extending the life and reducing maintenance on the automation.”
As excited as companies are to embrace 3D printing techniques, Sears says there are limits to the technology. Low print speeds will keep AM parts out of high-volume production for the foreseeable future, the technology can’t reproduce all of the materials automotive designers use, and it’s not cost competitive with injection molding for plastics.
However, the potential for improving operations and expanding capabilities for automotive producers is huge. With injection molds, tools are expensive, so plastics producers must produce high volumes of parts to recoup those tooling costs. AM technologies are lowering those tooling costs, making injection molding more affordable for lower-volume production runs.
“If we can make this tooling less expensive, it really offers the company the ability to refresh products more quickly because there’s not as much legacy cost that needs to be recouped,” Sears says.
He adds that it will be easier to justify specialty vehicles, such as Ford’s GT, if tooling costs fall quickly.
“When you’re making a low-volume vehicle, you’re still investing a significant amount of money in tooling,” Sears explains. “If you could now eliminate that investment, or reduce that amount, why not make more of those specialty vehicles?”
Ford Motor Co.