Forming a new approach
Hydroforming is no longer a brand new technology, but it may be the solution for new applications
Attendees of the fifth Hydroforming Conference and Exhibition, organized by the Tube & Pipe Association, International, and the Society of Manufacturing Engineers, learned that hydroforming technology is not dead yet.
Hydroforming's not dead yet, according to Murray Mason, vice president of engineering for Van-Rob, a Tier 1 automotive supplier based in Aurora, Ont. In fact, the metal tube forming technology may be on the verge of a renaissance.
"It's not as new as it was [in the late 1990s] and the hype has died down. But you will find there's a lot of new things to take notice of," he told the audience gathered for the 5th annual North American Hydroforming Conference and Exhibition, organized by the Tube & Pipe Association, International®, and the Society of Manufacturing Engineers.
Attendees learned firsthand of what Mason spoke. They learned how new tools are helping hydoformed parts achieve a new level of formability; how ancillary technological developments are helping to make the hydroforming process more cost- and time-efficient; and how the technology is being used in new applications.
Still doubt about the future of hydroforming? Muammer Ko, associate professor and director, Center for Precision Forming, Virginia Commonwealth University, Richmond, Va., led off his presentation with these points:
- The U.S. uses 25 percent of the world's oil production, and almost 70 percent of that goes to transportation.
- Anything that can be done to reduce 10 percent of the weight of a vehicle results in about a 6 percent to 8 percent savings in fuel for that vehicle.
- One of the best ways to achieve this type of weight reduction is through the use of hydroforming.
As an example, he talked about an aluminum radiator support for a passenger vehicle. In the previous design, the part was stamped, comprised 17 unique parts, and weighed 16.5 kg. The hydroformed part, on the other hand, comprised 10 parts and weighed 11.5 kg.
Ko made this point in his presentation, "Warm Hydroforming of Lightweight Materials": Researchers believe that the incorporation of aluminum and magnesium into automotive part design could open the doorway to huge weight savings. For instance, an aluminum part that replaces a steel or cast-iron part means a mass reduction of about 40 percent to 60 percent.
The key to forming these metals, however, is the evolution of warm hydroforming. Warm stamping now is used to increase formability of aluminum and magnesium parts, but warm hydroforming can mean even more weight reduction and further part consolidation, when compared to conventional methods.
"Formability of aluminum and magnesium at room temperature is minimal, only about 15 percent [change in the original structure can take place] before some sort of failure," Ko said. "This greatly improves with warm forming."
Ko shared with the audience that adaptive isothermal finite element analysis and design of experiments delivered accurate prediction of proper temperature distribution. He also provided tips on getting the best quality out of the warm hydroforming process.
For those doing straight tube hydroforming with end feed, graduate student Alexander Bardelcik, University of Waterloo, Waterloo, Ont., discussed a way to predict tube performance during hydroforming.
Working with a 1,000-ton press, hydroforming dies, and a 250-kip end-feed actuator, Bardelcik conducted tests and developed hydroforming numerical models, which he used to ascertain extended stress-based forming limit curve failure criteria for certain hydroforming jobs. With that information in hand, he was able to predict failure pressure, formability, and failure location with consistent accuracy.
In his presentation, "Study on Work Hardening of Bending Operations on Hydroformed Parts," D.S. Park, Hyundai HYSCO, Korea, took a look at how forming activities before hydroforming can affect overall part quality.
After finding that bending operations can change the thickness and mechanical characteristics of a tube and create forming stresses in that same part, Park made the following suggestions to counteract those changes:
- Lower the expansion rate during the hydroforming process to prevent the excess expansion on the bending portion of the tube.
- Increase the end-feeding pressure to compensate for the thinness in the outer surface of the bent tube.
- Adjust the feeding pressure curve to prevent the rapid expansion on the outer surface of the bent tube.
As new approaches and tools stand to make hydroforming a more attractive metal forming process, new opportunities for using the technology may arise. Gary Morphy, president, Synthesis Solutions, Cambridge, Ont., suggested that the emergence of processes such as warm forming doesn't threaten the future of hydroforming. It's just one more metal forming tool in the tool chest.
"Stamping and welding, obviously, haven't gone away. But only a portion of that [work that traditionally has been stamped and welded] has gone to hydroforming," he said.
Today hydroforming is regularly used in automotive applications to produce frame parts such as side rails, cross members, and crush boxes. About 50 percent of those parts are made with hydroforming presses, according to Prashant Soman, a process engineer, Schuler Hydroforming Inc., Canton, Mich. That volume is expected to decline because of slowing truck sales in the U.S.
Morphy said he believes that it's imperative to point out to potential users that while hydroforming may be looked upon as a slow process—with its 20- to 30-second cycle time—it offers savings with its ability to combine parts that would have to be joined manually in traditional designs. Additionally, proper feasibility assessments for potential applications actually can yield a hydroforming process that might be economically attractive for low- and medium-volume parts, he added.
Morphy said new markets that might benefit from hydroforming include plumbing fittings, furniture frames, building products, lifting devices, and medical applications.
Schuler Hydroforming briefly discussed its new forming technology, HEATforming®, which may lead to new forming opportunities. Instead of relying on a room-temperature, water-based emulsion pressurized to 30,000 PSI as the forming agent, this new process relies on an air/nitrogen mix pressurized to 3,000 PSI and heated between 350 degrees C and 1,100 degrees C. Because less pressure is needed, a lower-tonnage press can mimic the forming capabilities of a much larger press used for hydroforming.
Soman said the technology currently is used to form aluminum, magnesium, and brass parts, and research into forming mild, stainless, and high-strength steel using the same process is under way. The new forming process can deliver sharp definition of edges and corners, formed threads, and up to 400 percent circumference expansion, all with limited wall thinning, according to the company.
Schuler believes the technology would make sense for the fabrication of all-terrain vehicle frames, outdoor power equipment, bicycle frames, bathroom and kitchen fixtures, sporting equipment, furniture, and door and appliance handles.
An Up-close View
The conference ended with a visit to Martinrea International Inc., a Tier 1 automotive supplier in Hopkinsville, Ky. The 350,000-square-foot facility produces automotive chassis and suspension components for the Ford Mustang®, Ford Focus®, Mazda 6®, and Chevrolet Malibu®.
The facility has been hydroforming parts since 1998. Today about 12 percent to 15 percent of the company's forming and fabricating activities center around hydroforming.
The company's hydroforming cell consists of two AddisonMckee tube benders, an automated lubricator, a 200-ton Schuler preform press, a 5,000-ton Schuler hydroforming press, a Haven Manufacturing Corp. tube cutter, and four Motoman material handling robots. Four people—two unloaders, a tool and die technician, and a maintenance technician—keep the cell running.
If you are interested in learning more about hydroforming, visit www.thefabricator.comand click on the Hydroforming tech cell on the left-hand navigation bar. If you want to learn more about future hydroforming conferences offered by TPA, visit www.tpatube.orgor call 815-399-8775.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.