ere for you. That was a key message shared during a Sept. 30 webinar given by the Aluminum Association that focused on the future of vehicle lightweighting.

ere for you. That was a key message shared during a Sept. 30 webinar given by the Aluminum Association that focused on the future of vehicle lightweighting.

“A brand-new study by DuckerFrontier tells us that in your companies’ work to electrify fleets, aluminum is going to be your preferred material,” said Tom Dobbins, Aluminum Association president and CEO, addressing attendees that represent parts of the automotive supply chain.

“DuckerFrontier interviewed participants throughout the automotive value chain, including automakers. Data tells us that aluminum will remain the fastest-growing material as a way to reduce mass. Whether you are working on an electric vehicle or designing a multi-material vehicle, the aluminum industry is here for you,” Dobbins said.

We expect electric vehicle growth will drive aluminum growth.

Russ Long, chief engineer for the Ground Transportation Products unit at Arconic, said that aluminum usage in passenger vehicles has steadily increased since the Aluminum Association began conducting surveys in 1975.

“In 2020, vehicles in North America contained 459 pounds of aluminum. That is projected to grow to 570 pounds in 2030—this includes power train, closures, suspension. The common uses in the early years, 1975 to 2000, were largely castings, heat exchangers, engine blocks, transmission cases and wheels.”

In the early 2000s, cast aluminum suspension components became common. Over the last 15 years, the use of aluminum sheet, extrusions and castings in body in white and closures applications has been the fastest growing segment, Long said. Closures include the hood, fenders, deck lids and doors.

Below left, laser welding a Ford F-150 aluminum frame. Right, aluminum cylinder heads made at GM’s Defiance Casting Operations.

Below, laser welding a Ford F-150 aluminum frame. Very bottom, aluminum cylinder heads made at GM’s Defiance Casting Operations.

Add-on effect

“Quite often,” Long said, “we see OEMs select a weight target and move down the list—hood, fenders, deck lids, doors—until they reach their weight reduction target. This weight reduction is called primary. There are other weight savings that come along, called secondary weight savings. If you lightweight the body and closures, you will also likely reduce the size of the power train, or reduce the size of brakes or the fuel tank. So those are considered secondary.

“If you save 100 kilograms in primary, you can save 25 kilograms in secondary weight reductions,” Long said. “A convenient rule of thumb is a 10 percent reduction in curb weight results in a 6 percent improvement in fuel economy. So the weight reduction can have a significant impact on performance and fuel economy.”

Hybrid models

Aluminum isn’t new to the automotive industry. “The Audi A8 has had aluminum body in white (BIW) and closures since 1994. The Audi R8 and most sports cars have been aluminum for some time or are moving to carbon fiber because the light weight is key to their performance.”

In 2008, Audi released the TT, an early hybrid steel and aluminum body in white. “This vehicle has an aluminum front end and is more steel-intensive in the rear to provide better weight balance. The Audi Q7 is a recent vehicle using a hybrid steel and aluminum BIW and aluminum closures,” Long said. “It’s all aluminum closures, a largely aluminum rear and front end with a steel safety cage. This is a trend: More vehicles mix different materials as the design moves forward.”

In the case of the Audi Q7, the components are 48 percent steel and 52 percent aluminum by weight.

A majority of Jaguar vehicles have aluminum bodies. The Jaguar XJ has been aluminum since 2003, the Jag SF since 2008, and XE and F types since 2015 and 2013. The Jaguar F-Pace is a hybrid BIW with aluminum closures. The Jaguar I-Pace, an electric vehicle, is all aluminum BIW and closures. It was named EU’s Car of the Year in 2019, Long said. The Range Rover saved 420 kilograms by using aluminum.

“We have been speaking about electric vehicles. The Tesla lineup, Model S and Model X, are all aluminum BIW and closures. The models 3 and Y are hybrid BIW with aluminum closures. If we look to the most recent Mercedes-Benz C Class, it uses all aluminum closures and roof, and some BIW components. By weight, it is 24.8 percent aluminum, Long said.

Conversions

Among the U.S. carmakers, Ford’s 2015 F-150 cab, doors, fenders and box were converted to aluminum, riding on a steel chassis. “This configuration resulted in a 700- to 890-pound curb weight reduction, depending on the drive train and the size of the vehicle,” Long said.

Comparing the steel F-150 to the aluminum F-150, Long noted that both had aluminum hoods. “The fender weight savings was considerable. Tailgate doors also contributed to weight savings. The cab was 40 percent plus [weight savings], as was the cargo box. Overall, it was a 44 percent reduction in [weight across the] closures, cab and cargo box.”

Subsequently, the Ford Super Duty, Expedition and Lincoln Navigator were made with all-aluminum cabs and closures. Jeep adopted aluminum hood and doors for its Wrangler and Gladiator platforms. The 2019 Chevrolet Silverado pickup truck included an aluminum hood, doors and tailgate. The 2019 Toyota Rav 4 used an aluminum hood, fenders and lift gate.

Selections

“There is an ongoing trend where material characteristics are used to select specific compounds,” Arconic’s Long said during the webinar. “One extreme is an aluminum body in white, the other is a steel body in white. Hybrids fall in between the weight range.

“If you only need to save 50 kilograms, and an aluminum BIW can give you 100 kilograms, you can use selected parts in select areas. Press-hardened steels are dominating the safety cage area. Aluminum parts in the cage can do the job and save 30 percent [by weight], whereas in other areas, aluminum would save 40 percent or 50 percent,” he said, “so it’s logical to use some steel components. The difficulty is you have to change your methods for joining steel and aluminum. OEMs have different approaches to doing that.”