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LIGHTWEIGHTING: Now Comes the Hard Part

Bill Koenig
By Bill Koenig Senior Editor, SME Media

Automakers, suppliers have made vehicles lighter but the task is getting more difficult.

An operator at Constellium’s new plant in White, GA, conducts a quality check on an aluminum bumper beam.

Automakers, working closely with suppliers, have reduced the weight of their vehicles, in some cases by hundreds of pounds. They’ve introduced new materials, stepping up the use of high-strength steels, aluminum and magnesium. They’ve found new ways to join parts made with different materials together.

Now comes the hard part—continuing the momentum, going deeper into vehicles and components to find weight savings. The industry, while doing all that, has to balance safety and customer demand for more vehicle features.

“Pressure is on the engineer to get weight out,” said Jay Baron, president of the Center for Automotive Research (CAR; Ann Arbor, MI).

“What is happening, the pressure to reduce is forcing the industry to reduce the margin of error,” he said. “Are we going to lightweight to be less safe? The issue of crash worthiness is huge.”

Some companies, amid their lightweighting efforts, discover unanticipated problems.

Mahle Industries (Farmington Hills, MI) while developing lighter weight automotive components found that some pistons and piston rings could crack unpredictably. Engines are getting smaller while being equipped with turbochargers to maintain power. Thus, there’s more strain.

“This is about downsizing,” Joachim Wagenblast, director of product development for engine systems and components in North America for Mahle, said at a June media briefing by auto suppliers. “Downsizing is about lightweighting. You have to get more power out of a smaller combustion chamber.”

“You have to make these products more robust,” Wagenblast said in a follow-up interview in July. “You increase the wall thickness of some areas. You develop new coatings.”

There are also limits, in some cases, how quickly vehicles can go on a diet.

New ‘Architectures’

General Motors Co. (Detroit) has achieved its biggest weight reductions following major vehicle redesigns, including new “architectures.” Lighter materials for component designs were included as part of the process. For example, the company reduced the weight of its GMC Acadia by 700 lb (322 kg).

The GMC Acadia shed 700 lb (322 kg) after a redesign involving a new “architecture.”

“We could pull out all the stops,” said Rob Peckham, GM technical integration engineer for mass strategy and tools. “Every bit of learning could be put in there. We’re not going to make a major architecture change every other year. To get mass out, you have to make major investments.”

Lightweighting stems from regulatory and other pressures to improve fuel efficiency and reduce greenhouse gases. Regulators, in rules set in 2012, set a target for the US vehicle fleet to average 54.5 mpg (23 km/l) by the 2025 model year.

Achieving that target has been complicated by consumers buying more (and heavier) trucks than regulators originally anticipated. The Trump administration said in March it was reviewing the target, set during the Obama administration. It’s not known how the review may affect the standards.

Given the lead times for developing vehicles, automakers and suppliers are proceeding with their efforts to cut weight of vehicles.

For example, Gestamp Automocion SL (Madrid) has opened a new North American research and development center in Auburn Hills, MI. Lightweighting will be one of the major tasks for the facility. The company estimates that body and structural parts comprise more than half of a vehicle’s weight.

“We want to be a global player,” said Paul Belanger, Gestamp’s director of research and development for North America. “We have to be close to where you develop” new vehicles. Gestamp customers include GM, Ford Motor Co., FCA US LLC and Honda Motor Co.

Gestamp previously co-developed with Honda a rear rail system made from high-strength steel for the automaker’s Civic. Energy from a crash is absorbed by system components.

“We worked collaboratively with Honda,” Belanger said. “That supports the need to build a North American R&D center. We were [previously] limited in R&D” in North America.

The new R&D facility has an area of 3425 m2 and has 45 employees, with plans to expand to 64 employees by the end of the year. It has crash simulation capabilities for body in white components and testing equipment for chassis components.

“We try to look at all of the emerging technologies,” Belanger said. “There is not a single answer” to lightweighting.

Constellium, an aluminum products maker, has expanded its automotive business because of lightweighting.

New Factory

The Netherlands-based company supplies Ford and BMW. It operates a plant in Van Buren Township, MI, and has opened a new 135,000 ft2 (12,540 m2) operation in White, GA.

An example of its offerings include a one-piece aluminum extrusion windshield header, which replaced a five-piece steel assembly.

An operator at Constellium’s Van Buren, MI, plant loads a bumper beam and crash boxes into a weld cell for assembly of a crash management system.

At the Michigan plant, such parts are bent so they can be attached to a vehicle. The parts are then heat treated to increase their strength. The factory also makes aluminum components for crash management systems designed to fold up and absorb energy in crashes.

Eric Krepps, the company’s vice president and general manager for Constellium Automotive Structures North America, said automakers will “combine parts and remove parts. We’ve done this with customers, it allows you to eliminate cost and weight.”

The company also sees electric vehicles as an opportunity. Regulators in California, the largest vehicle market in the US, and nine other states require sales of electric vehicles to reduce emissions. One concern with EVs is their range between charges.

“Driving distance is directly related to the weight of a car, the mass of the car,” said John Biel, engineering director for Constellium Automotive Structures North America.

It’s not just automakers and suppliers who are drawn to lightweighting issues.

‘Explosive’ Welding

There are academic studies related to the issue. For example, Ohio State University (Columbus, OH) is studying “civilized explosive welding” as a way to join dissimilar materials and avoid corrosion.

With the process, a thunderbolt rams one material into another to create a welded joint.

“It’s an early stage technology we’re committed to,” Glenn Daehn, professor of metallurgical engineering for the university, said in February at the Lightweight Vehicle Manufacturing Summit in Detroit.

“We think this is the best way to join advanced or dissimilar materials,” Daehn said at the conference.

Also involved are two institutes that are part of Manufacturing USA, a program set up under the Obama administration for academic institutions, non-profits and companies to collaborate on manufacturing technology.

The two working on lightweighting are Lightweight Innovations for Tomorrow (LIFT; Detroit) and the Institute for Advanced Composites Manufacturing Innovation (IACMI; Knoxville, TN). IACMI has a satellite office at LIFT’s headquarters.

New Equipment

Equipment has been installed this year at LIFT after the 100,000 ft2 (9290 m2) headquarters building’s electrical system was rewired. One large piece of equipment is a linear friction welder, that’s 60 × 40 with a 9′ foundation (18 × 12 and 2.7-m deep). There will also be a “beta area” where machine makers can demonstrate new models for up to six months.

Manufacturing USA institutes are intended to develop new manufacturing technology to the point that companies can commercialize them. LIFT members have participated in a series of projects, including one for an automotive differential that’s 50% lighter, according to the institute.

A work cell at Gestamp Automocion SL’s new North American Research and Development Center in Auburn Hills, MI.

“A lot of our portfolio is going after the 10, 20, 30% improvement,” said Alan Taub, chief technology officer at LIFT.

LIFT also is developing computer modeling to predict how different materials change during manufacturing. It’s dubbed Integrated Computational Materials Engineering, or ICME. It’s more informally known as the Materials Genome Initiative. “The engineers like to call it that,” Taub said. “It’s basically getting materials processing simulation tools fully integrated with product design tools.”

LIFT also is exploring “low investment, agile metalforming technology,” Taub said.

At IACMI, one of the primary missions is to develop new composite materials and find ways to spread their use in manufacturing. With automotive, IACMI is trying to develop “potential replacement of steel and aluminum with lower carbon footprint materials,” said Uday Vaidya, the institute’s chief technology officer.

One IACMI priority, he said, is to develop cheaper forms of carbon fiber that would be cost effective for auto manufacturing. Currently, the material is used in race cars and expensive production models such as BMW’s i3, Ford’s GT and Honda’s NSX.

“If we can get this into high production, it’s a very big breakthrough,” Vaidya said.

Reaching Limits

Lightweighting remains a high priority for the steel and aluminum industries.

The steel industry has developed high-strength and ultra-high-strength steels, which are strong enough so less of the material is needed compared with conventional steel.

“We’re getting to the limits of the [high-strength] grades available,” said Jody Hall, vice president of the automotive market for the Steel Market Development Institute. “But new steels are being developed.”

One lightweighting issue, she said, is “we have to get more power out of smaller engines. We are studying pistons and crankshafts because of increased performance.”

Hall also said steel will remain in the picture as the industry shifts from steel-dominant to “mixed material” vehicles.

Body in white of vehicles are “almost 100% steel,” she said. “Half of body in white are advanced higher strength steels…Steel is still going to be around with higher penetration of alternate materials in the body.”

The aluminum industry also is optimistic.

“There’s an increasing need for mass reduction,” said Doug Richman, chairman of the technical committee of the transportation group of the Aluminum Association trade association. “It gets more stringent year over year.”

Aluminum previously made inroads in wheels, engines and cylinder blocks, Richman said. “Now the major area is the body. That’s certainly for the next 10 years where the growth will be.”

‘I Feel Great’

Aluminum’s biggest inroad into vehicle bodies was Ford’s F-150 and Super Duty pickups. The trucks sell at high volume—which justified Ford’s investments in revamping body shops. Also, the trucks are North American products made at a handful of factories.

Nevertheless, as the industry shifts to multi-material cars and trucks, Richman likes aluminum’s chances.

“There are 300–350 metal parts in a car body,” he said. You look at each individual part and ask what is the material for that part.” Aluminum will win its share of such decisions, he said.

“I feel great,” Richman said. “I’m somewhat relieved.” The aluminum industry, he said, would struggle “if everybody stampeded to all aluminum vehicles.”

The main certainty is that lightweighting remains a marathon.

“We’re adding more lightweighting technology every year,” said CAR’s Baron. “Regulators have accelerated demand for these lightweighting technologies.”

Added GM’s Peckham: “We’re pushing everything to its limits. We’re looking at everything. It’s just the challenge of doing it on all fronts.”

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