Five years ago, automotive lightweighting was supposed to be steel versus aluminum, but the consensus today is that mixed
materials is the way to go
Earlier this decade, the auto industry moved to lighten cars and trucks. It was supposed to be a competition between steel, long the dominant vehicle material, and aluminum. The latter got a boost when Ford Motor Co., Dearborn, Mich., bet big on aluminum, making aluminum bodies for its F-150 and Super Duty pickups.
However, no outsized rush to aluminum took place. The material is being used more than it once was, making up a variety of parts. Aluminum is making more incremental advances since Ford’s trucks took on aluminum bodies. Meanwhile, the steel industry has countered with a mix of high-strength and ultra-high-strength steels. Such steels are stronger, meaning less of the material is needed, reducing weight.
A consensus has emerged. The future for the industry is a mix of materials, a mix that will vary from vehicle to vehicle. It’s also likely to be a more complex future, with composite materials making inroads in the long run.
“You have to take into account all sorts of factors,” said Jay Baron, retired president of the Center for Automotive Research (CAR), Ann Arbor, Mich. Vibration and stiffness figure into the equation, he said. And there’s cost. “It’s much more than weight and strength.”
James Truskin, technical fellow-body advanced architecture at FCA US LLC, Auburn Hills, Mich., described how that automaker has viewed the materials evolution.
“We did see a strong swing to consider all-aluminum vehicles,” he said. “It started to swing back with a mix of steel content. It was a challenge to meet safety tests with aluminum. We stayed the course with steel because we saw these new steels coming.”
At the same time, he said, “For our volumes and our infrastructure, we’ve been strategic in picking the right material” to reduce vehicle weight.
The aluminum industry, meanwhile, likes its prospects. “It is by no means slower growth,” said Ganesh Panneer, vice president and general manager, automotive at industrial aluminum supplier Novelis Inc., Atlanta, and a previous vice chair at the Aluminum Association’s Aluminum Transportation Group.
Studies have indicated aluminum growth in vehicles to 2025 and beyond, he said. The material has applications for closures such as doors, deck lids and fenders.
What’s more, he said, 200,000 tons of automotive aluminum capacity will come on line in early 2020. The aluminum industry has been coordinating with automakers concerning bringing on more capacity.
Lightweighting became an emphasis after the Obama administration instituted fuel efficiency regulations through the 2025 model year to reduce emissions. The administration of President Donald Trump wants to ease up on the regulations.
However, in late July Ford, Volkswagen, BMW and Honda reached a deal with the state of California to increase gas mileage standards and reduce greenhouse gas emissions. And automakers still face regulatory pressure in China and Europe, with China also wanting automakers to make more electric vehicles. Many automakers sell globally, so they must take the various regulatory plans into account. That means lightweighting still remains a priority.
For automakers, said Arun Kuman, director of the automotive practice at consulting firm AlixPartners LLP, New York, “I can’t develop a platform that only works in North America or only works in China.”
Further, cutting weight for EVs is seen as one way, along with improvements in batteries, to extend range.
“If I’m selling reasonable quantities of electric vehicles, I’d want to put that into North America.” Kuman said. EVs need to cut about 400 lb (181.4 kg) to help increase range to win the confidence of consumers, he added.
All of this is occurring as the industry faces new financial strains. The global industry is entering a “profit desert,” AlixPartners said in a June report. Sales in key markets are slowing while automakers and suppliers are investing in EVs, self-driving and “connected” vehicles. Automakers have announced spending of $225 billion for “electrification” from 2019 through 2023, according to the consulting company.
That’s happening while the U.S. market is forecast to fall to 16.9 million vehicles this year, down from 17.3 million in 2018. Deliveries may slip to 15.1 million in 2021. The China market is expected drop to 24.8 million vehicles in 2019 from 27 million last year. The European market is forecast to slip to 20.4 million this year, down from 20.6 million in 2018, while it is predicted to increase 1.3 percent annually through 2026. As a result, the auto industry will be coping with making a lot of investment amid stagnant conditions. The drive to make vehicles lighter will face cost constraints.
Cost is one reason why high-strength and ultra-high-strength steels have been utilized. “Even the large vehicles have to be more affordable,” said Jody Hall, vice president of automotive for the American Iron and Steel Institute, Washington, D.C.
Switching to aluminum bodies like the Ford trucks requires new body shops. The new steels can be used with existing facilities, although some adjustments often are needed for stamping presses so tools and dies don’t wear out more quickly.
At FCA, the company seeks to apply lightweight materials where there is “direct customer benefit,” according to a 2018 presentation concerning its Wrangler JL. The company achieved 66 kg of lightweighting. That was partially offset by almost 15 kg for features. Still, the model finished 51 kg lighter than its predecessor model. Sections that ended up lighter included the body-in-white and closures.
The automaker said ultra-high-strength steel and high-strength steel in the frame maximized energy absorption and improved safety.
Some aluminum parts also contributed to weight reductions. “We were able to achieve that by bolting on most of the aluminum content,” FCA’s Truskin said. “It doesn’t upset the manufacturing process. We use the same bolting process as with steel closures.”
FCA has reduced weight on other models, including its 2017 Pacifica minivan, which used high-strength steel, aluminum and magnesium to pare 168 lb (76.2 kg) from its body structure. The minivan overall was 250 lb (113.4 kg) less than its predecessor model. Examples of weight reduction included using aluminum for its hood and sliding doors. The model’s liftgate has an aluminum outer panel bonded to a cast-magnesium inner panel. The combination reduced with by 18.5 lb (8.4 kg) per vehicle.
FCA has more lightweighting plans, though the company says it can’t specify them now. “We’ve got some very exciting improvements,” Truskin said. “There’s more that we can do with steel. We can be more aggressive in that area.”
With aluminum, he added, “There’s still a lot of room to improve. We’re considering how to integrate aluminum and not just bolt it on. We’ve used a lot of aluminum for a long time, and we’ve used magnesium for some time.” He described the company’s approach to lightweight materials: “We’re doing it on components the customer touches and uses.”
Some companies and groups are developing advancements for the future. Techniplas, a supplier to automakers such as BMW and Daimler AG, said it has developed a process involving 3D printing and artificial intelligence (AI) to make parts up to 47 percent lighter. AI helps calculate how to minimize the amount of material used to make parts while 3D printing enables new shapes. With 3D printing, parts are made from a digital design. According to the company, automakers can send 3D printed models to Techniplas to have parts printed and delivered.
‘One Correct Answer’
“In our case, AI helps us to do a few things at the design phase primarily using algorithmic topology,” said Avi Reichental, Techniplas Digital CEO, in an email interview. “We believe there is only one correct answer for each design optimization problem … if you set the design problem correctly. AI helps in determining that.”
Automakers have been using 3D printers for design and to make prototypes. Companies gradually are discussing their efforts publicly. Ford last year provided press tours of its Advanced Manufacturing Center in Redford, Mich., a Detroit suburb. The facility, among other things, tests 3D printers from various manufacturers for adapting to vehicle manufacturing.
Reichental, a former CEO of 3D Systems, said use of 3D printing is likely to expand in the industry because of lightweighting.
“You can mimic the kinds of efficient, high-performance structures we find in nature,” he said. “This is why we’re seeing an explosion in the adoption of 3D metal printers, especially in aerospace, automotive, and also in the medical device industry.”
Lightweight Innovations For Tomorrow (LIFT), one of the Manufacturing USA institutes developed under the Obama administration, is stepping up its efforts to develop lightweighting technology.
The Detroit-based group now operates a linear friction welder, which can produce large parts. The massive machine weighs 122,000 lb (55,338 kg). Most of it is below the floor of LIFT’s production area, which has various machine tools and robots. The friction welding technology is used in aerospace to reduce weight in parts. LIFT has said it will explore how the technology can be deployed in other industries, including automotive.
First in North America
The linear friction welder is the first in North America. Until now, companies had to go to Europe to use such a machine on projects. It’s known as the LF35-75 and was built and installed by Manufacturing Technology Inc. (MTI), South Bend, Ind. Both MTI and LIFT will have shared capacity of the machine while MTI will maintain it. The welder will be used for MTI customers and for LIFT projects. The linear friction welder also enables joining multiple materials and creates unique shapes.
LIFT also is becoming more involved in developing technology that can be commercialized. Previously, LIFT was a place where companies, non-profit groups and universities could collaborate on basic research. It would be up to companies to commercialize the technology from there.
The organization now is continuing development beyond the early stages. “In this country, lightweighting is tremendously important,” said Nigel Francis, LIFT’s CEO. “We’re proponents of a multi-material solution. The solution is likely to be many, many materials.”
In addition, suppliers are looking to take weight out of systems as they try to improve performance. In chassis for example, Brakes International, Eindhoven, Netherlands, is developing its brake-by-wire Smart Brake, which it plans to introduce in 2025. Smart Brake eliminates hydraulic braking. It replaces the master cylinder, brake lines, brake fluid, fluid-driven caliper pistons and anti-lock braking components. Braking will be done electronically with electric motors that exhibit a high clamping force on brake pads and rotors. Each wheel end will be individually controlled. Chassis Brakes says the system has a simplified design.
Looking ahead, lightweighting efforts will continue and utilize other materials. One possible area is composite materials, such as carbon fiber. Some high-end “super cars,” such as the Ford GT and Acura NSX, use carbon fiber. How quickly composites spread is uncertain.
“I don’t think we’re going to see a lot of growth in composites for the next 10 years,” said Jay Baron, the retired CAR president. “We are constrained by costs. It is not a technology issue.”
Advancements in design software also will affect efforts to reduce vehicle weight, Baron said. “New software recognizes the complexity and recognizes the interaction” of materials, he said. “We will see a proliferation of new materials throughout the car.”