In an ongoing effort to lower vehicle weight, cut costs and reduce waste, Ford increasingly is turning to hydroforming to create critical parts and components.
The process, which involves injecting water under high pressure into a die to shape a variety of materials, offers many benefits over the traditional method of stamping hot steel.
Ford says hydroforming results in improved structural performance, avoidance of the cycle time and heating requirements associated with traditional stamping and a reduction in material scrappage rates.
The technology has existed for decades, but recent advancements have made the process more cost-effective and have prompted Ford to adopt it for a wider variety of parts and components, says Bruno Barthelemy, global chief engineer-body structures, closures and body CAE.
“In the 1990s it was not really efficient because there would be cracking (and) you were limited in the type of design you could do,” he tells WardsAuto. “Now we have pressure-sequence hydroforming where we tailor the pressure as we’re closing the die.”
By slowly increasing the water pressure as the die closes, Ford is able to create more complex shapes and ensure structural rigidity, Barthelemy says.
Although hot-stamped boron steel is stronger than the high-strength steels used in hydroforming, the process allows for better design, rather than stiffer steel, to make the body shell stronger.
Ford’s latest use of the process can be found on the upcoming all-new ’13 Fusion midsize sedan, which has hydroformed A- and B-pillars and roof rail.
By using hydroformed steel tubes for the pillars and rail, the auto maker says it shaved 9.2 lbs. (4.2 kg) off the body-in-white, leading to improved fuel economy and reduced emissions.
“With all the requirements in fuel economy in North America and carbon-dioxide emissions in Europe, weight savings is critical in all vehicles, so we’re looking at it very carefully,” Barthelemy says. “Fuel efficiency is a pillar of the company, and one of the tools to deliver that is the weight of the vehicle itself.”
Hydroforming also eliminates the need for additional stampings and reduces the number of spot welds and joints.
“In terms of structural rigidity, it’s better because one of the weaknesses of any structure is the joints,” he says. “The load always tends to concentrate at the joint.”
In terms of reducing scrappage, Barthelemy says traditional steel-stamping often results in the loss of 30%-40% of material, but with hydroforming the scrappage rate is only 5%-10%. “A roof has little scrap, but when you think about a body side, you have big door openings you’re throwing away.”
Past uses of the process include the roof rails and A-pillars of F-Series pickups, and as new products are introduced, Barthelemy says Ford will employ hydroforming where it makes sense. That may involve using the process to create components for smaller and hybrid-electric vehicles.
“We are considering smaller vehicles,” he says. “There’s no drawback (to hydroforming), it’s just a question when you introduce a new technology in a plant you have to invest. The improvements (from hydroforming) may not be big enough to pay for the investment itself.”
Barthelemy is mum on what cost savings result from the process, saying that information is kept confidential.
“The reason we went to hydroforming is because we saw cost savings buying less steel and having less scrap,” he says. “We’re not getting penalized by using hydroforming; it’s delivering the performance for weight and cost savings.”