Fabricator rides new wave of interest in hydroforming
American Hydroformers ready with expertise, equipment, capacity
Founded in 2003, American Hydoformers Inc. arrived on the scene a little too late to catch the first big wave of interest in hydroforming. A few automobile manufacturers had been oversold on the technology and were cautious to continue to convert parts to hydroforming, but AHI didn’t stumble and fall. Wise investments in equipment gave the company a unique and thriving position in the industry.
Every once in a while a revolutionary, disruptive technology comes along, and it’s only a matter of time until it displaces its predecessor. An obvious example is the light bulb, which put an end to gas lamps. On the other hand, many technologies don’t take over, but gain a foothold in an industry, grow to fill a niche, and then coexist with other technologies. Hydroforming is one example. Hydroformed parts won’t displace stamped parts of stamped-and-welded assemblies, but for some components, the hydroforming process delivers a better part more efficiently than a conventional process can.
Although using fluid to form sheet metal has been around since the turn of the century, efficient tube hydroforming is a much more recent development. It became a hot topic in the early 1990s when it emerged as a viable process for making tubular automotive parts. 1 Frame members, engine cradles, roof rails, and exhaust components are typical examples. Converting a part from a stamped-and-welded structure hinges on several considerations, both technical (can the part be made stronger or lighter?) and business-related (can the part be made faster or at lower cost?).
Technologies rarely enjoy a trend of unimpeded growth, and hydroforming is no different. In the headlong rush to adopt the technology, a few companies switched some applications to hydroforming that should have been left alone; eventually some of these were changed back to stamping and welding. 2 Despite occasional setbacks, the technology’s position in the automotive industry continued to strengthen. Knowledge of the process spread, and eventually some engineers took the next step: designing new parts specifically to be hydroformed, taking full advantage of its benefits.
It was into this environment that American Hydroformers Inc. (AHI), Fort Wayne, Ind., was launched in 2003.
The New Kid on the Block
“This is a great technology,” said Mark Blasi, a professional engineer and project manager for AHI. “The original tube is round, but the final structure can be rectangular, triangular, oblong, or any shape,” he said. Indeed, while some hydroformed parts are simple designs, many parts have a combination of cross sections. It’s also viable for a large number of alloys with a variety of characteristics.
“We can hydroform high-strength, low-alloy [HSLA] material, materials that have high yield strengths—55,000, 60,000, even 65,000 PSI—dual-phase steels, and so on. These materials are really strong, which allows the component designers to use thinner-wall material. This is what it’s all about—mass reduction was the technology’s big promise, combined with all the unusual shapes this process can do,” Blasi explained.
Automobile manufacturers discovered long ago that expanding a tube inside a die often results in a stiffer, lighter assembly made in less time than stamping two component halves and welding them together. Additional benefits are increased design flexibility, improved crash performance, and easier fastener integration; meanwhile it can reduce the tooling cost and assembly cost, which reduce the part cost. It also can reduce the finished part’s dimensional variability.
However, it’s not necessarily easy to build a successful hydroforming business. AHI did it by bringing together a unique combination of equipment and expertise to carve out a niche.
Presses. AHI uses big presses—big in their bed dimensions and closing capacities. The largest has a bed that measures 124 by 84 in. and develops 5,500 tons of closing pressure. The others are a 4,000-ton, triple-action press with a bed that measures 120 by 245 in. and an 1,800-ton press with a 130- by 98-in. bed. These capacities provide the company the ability to handle long parts, such as roof rails, and high-yield-strength alloys.
“Outside of Tier 1 manufacturers, not too many companies have presses this size,” Blasi said. He contrasted these big automotive parts with plumbing components, which require much smaller presses, from 500 to 1,000 tons.
Processes. “We have rewritten quite a bit of the software for our hydroforming machines,” Blasi said. “We wanted to integrate some of the steps, so we could do the preforming and forming in the same step. We also needed a relief valve to limit the internal pressures to 3,000 PSI (200 bar) while it was in the preforming stage,” he said.
Rewriting machine software sounds more than bold, but Blasi explained that the original software was written in 1985. Such machines are still up to today’s manufacturing tasks, but after 25 years, they were due for updates to keep up with programming advancements and improvements in solid-state control technology.
Cylinders. Hydroforming requires large hydraulic cylinders to develop sufficient pressure to seal the parts during forming. Blasi cited parts made from INCONEL® alloy, which in some cases need up to 45,000 PSI of pressure. AHI uses a modular system to keep costs down (see Figure 1). For some applications, this cuts the tooling cost in half.
Cutting. After they are formed, parts with complex contours and unusual features require a sophisticated tool for piercing, cutting, and holesizing. For many parts, the only choice is a 3-D laser cutting machine. Initially AHI outsourced laser cutting; these days it has three gantry-style machines (see Figure 2).
Finite Element Analysis. Developing capabilities is one thing; understanding your limitations is another, equally important thing. AHI relies on outside expertise when necessary. Simulation is one area in which it relies on an expert.
“To do finite element analysis [FEA] right, you almost need a Ph.D.,” Blasi said. “We don’t need to do FEA often, but for a rigorous program of checks and balances, we partner with a specialist with a lot of experience in complex shapes and modern alloys.”
Integration, Cooperation, Collaboration. No man is an island, nor is any business. A company that relies on forming dies as much as AHI does would benefit from having a partner that specializes in machining tools and dies, and AHI has one in Zemco Manufacturing Inc. Both are part of a small conglomerate of manufacturing companies, co-located in an industrial complex, an arrangement that provides quite a bit of crossover of metalworking capability and expertise.
AHI collaborates with companies outside the building as well.
“We often do die runoffs for our diemaker’s other clients,” Blasi said. If this sounds like AHI occasionally assists its competitors, indeed it does.
“When Tier 1 suppliers are out of capacity, we run parts for them,” he said.
What happens when AHI is in a tight spot?
“We had to rely on another company to run parts for us about five years ago,” he said. “We’d rather be in charge of our own destiny, so when this happened, the owner decided that we should add more capacity. Now we have plenty. For example, we have two lasers cutting features in frame rails for a big luxury car. We don’t need both machines for that part, so when we get some extra work, we can handle it. We just run the machines a little faster. When things slack off, we use both machines but we run them slower. This has a second benefit—when they run slower, they require less maintenance.”
Niche. Although AHI rubs elbows with many Tier 1 suppliers, it doesn’t consider itself to be a full-fledged member.
“We enjoy doing special parts,” Blasi said, citing the challenges that come with developing processes to manufacture new and unusual parts.
Part volume is another factor.
“We can handle high volumes, but this isn’t where we specialize,” he said. “We like opportunities with volumes under 90,000 per year.”
Riding the New Wave of Interest in Hydroforming
Although AHI was launched after the big wave of hydroforming interest in the 1990s, the company has seen this technology ripen throughout the current decade, and it’s enjoying a small resurgence in interest in the process. Two developments, both related to transportation, propelled inquiries over the last few years.
EPA Guidelines. One was an initiative by the Environmental Protection Agency (EPA) to reduce the amount of particulate matter generated by diesel engines. The EPA didn’t put the entire burden on the truck manufacturers; its two-pronged approach requires a reduction in the fuels’ sulfur content and a more aggressive process for dealing with the exhaust. The exhaust systems have provided additional work for quite a few manufacturers. The exhaust filtration units aren’t small—AHI makes parts for a unit that is roughly the size of a clothes dryer—so to save weight several of the components are hydroformed.
Second was the updated corporate average fuel economy (CAFE). After climbing from 18 MPG for passenger cars in 1978 to 27.5 MPG in 1990, it stalled. Oil was cheap and fuel efficiency wasn’t a pressing concern. Much changed over the next few years, renewing the focus on fuel consumption. The CAFE standard proposed in 2009 requires an average of 28 MPG for the 2012 model year and is set to climb to 46 MPG by 2025. 3
A Look to the Future. More than 20 years after the first mass-produced automotive part came out of a hydroforming press, does the technology have more to offer? Apparently it does.
“Manufacturers are continuing to explore new and unusual shapes, but they’re also trying to use hydroforming more effectively, across platforms,” Blasi said, referring to the practice of using a single component such as an engine cradle in as many models as possible. Meanwhile, knowledge about the process continues to spread into industries that aren’t yet hydroforming-intensive.
“We get occasional inquiries for making parts for downhole well tools,” Blasi said. “We’re also looking at an aerospace application, an effort to replace a casting with a hydroformed tube.” Other calls have come in from manufacturers involved in furniture, transmission components, and defense.
Much of this relies on the technology’s design flexibility, and while this is difficult to quantify, designers should keep in mind that an aggressive design and a not-too-ductile material aren’t mutually exclusive; an intermediate anneal can restore some of the ductility lost in earlier forming stages. On the other hand, the combination of reduced mass and increased stiffness is easy to quantify. Blasi gave an account of a high-profile part that showcased the process’s capabilities and helped solidify its reputation in the automotive industry.
“One of the early hydroformed components had half the weight and five times the torsional rigidity of the competing component,” he said. “GM was pleased with the results and started hydroforming that part of the Corvette®.”
1. Gary Morphy, “The evolution of tube hydroforming,” www.thefabricator.com, June 12, 2007.
3.Before 2012 passenger cars were treated as a single class of vehicle under the CAFE standard. Starting with the 2012 model year, passenger cars are divided into two classes based on footprint: less than 41 sq. ft. and greater than 55 sq. ft.
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