Aluminum is in the middle of industry lightweighting efforts
For global automakers, removing weight from their vehicles remains the top priority as they seek ways to meet a stringent federal fuel economy mandate by 2025 and other new pollution-control regulations. And, increasingly, they look to aluminum producers and extruders to help do just that.
The lightweight metal is one of the most relied-upon materials to help meet the 2025 standard, a recent annual WardsAuto survey shows. Vehicle manufacturers must meet the tougher standards but they don’t want to lose performance or aesthetics. This explains why aluminum is registering swift growth in exterior and structural applications as vehicle manufacturers substitute it for heavier steel, and increasingly look to expand its use for body components such as panels and closures as well as truck trailers.
Aluminum receives good marks as a lightweight material in existing models, including the best-selling Ford F-150 as well as models from Jaguar Land Rover. And every aluminum car and truck crash tested in the US has earned a 5-star safety rating as consumers indicate they like these vehicles’ fuel economy, durability, safety and overall performance.
R&D Innovations in Lightweight Aluminum
Aiding vehicle makers are research-and-development advances in developing new lightweight aluminum alloys and extrusion alloys and composites as well as new or improved fabrication processes. Investing in R&D is a critical strategy for aluminum producers and extruders and, increasingly, they are collaborating with vehicle designers and engineers to develop inventive solutions to further pare car and truck weights.
For instance, Sapa Extrusion North America opened a new $3 million automotive-focused Sapa Technology Americas R&D center in April 2016 in suburban Detroit to work more closely with the company’s business areas in serving OEM manufacturers. The R&D center has over a dozen of the company’s North America research team, including a specialist in joining technologies with a PhD in friction stir welding. Eight metallurgists work on new alloys, product development and applications. Another key to the personnel is a PhD mechanical engineer dedicated to computational modeling to optimize extrusion design for optimal weight savings.
Given the much tougher regulatory standards, the increase in R&D in new lightweight materials isn’t surprising. The WardsAuto survey found that respondents are only moderately confident that their existing materials will help meet the forthcoming standards, so they seek lighter substitutes.
Under the 2025 fuel economy and greenhouse gas emissions mandate, model year 2017–2025 light-duty vehicles would be required to get 54.5 mpg (23 kmpl). That figure, however, doesn’t include certain special credits that many authorities believe will translate to a 40 mpg (17 kmpl) standard in real-world fuel economy.
Related, through 2023, it is estimated that nearly 75% of total average vehicle weight reduction will pertain to the exterior and structural segment, with body and frame applications accounting for nearly half, and this has sparked development of lightweight materials.
Aluminum’s Role in Decreasing Vehicle Weight
Lightweighting is also being driven by such factors as escalating increases in car weights triggered by the constant addition of features to vehicles; the development of electric and other fuel systems that demand lighter weight to improve energy efficiency; and ever-growing global warming concerns. The R&D drive for lighter-weight aluminum and aluminum extruded materials supports these needs and can offer the most cost-effective lightweighting solutions.
Automakers remain challenged by consumer demand for additional vehicle features that commonly rely upon heavier steel and like materials. Safety, performance, and entertainment features all add to a vehicle’s weight. That’s why aluminum producers seek solutions that can replace the heavier iron and steel, through innovative design with aluminum extrusions and advanced aluminum alloys.
Consider that in 2015, the average new US vehicle produced contained 400 lb (180 kg) of aluminum, estimates Ducker Worldwide, a provider of auto industry trend data. By 2025, Ducker Worldwide forecasts, aluminum will comprise more than 75% of pickup truck body parts, 24% of large sedans, 22% of SUVs and 18% of minivan body and closure parts.
For autos, the most commonly used aluminum and aluminum extruded alloys are the 5000- and 6000-series, and companies such as Sapa Extrusions North America are focusing on improving the 6000-series alloys. The 6000-series alloys currently offer the most cost effective solutions. Sapa is also exploring other alloy systems to further advance lightweighting opportunities.
In crash performance tests, researchers at Ohio State University’s Center for Precision Forming found that two B-pillars—one formed from hot-stamped boron steel and the other from 7000-series aluminum—showed similar performance although the aluminum part cost 40% less.
New Manufacturing Approaches Embrace Aluminum
Automakers such as General Motors Co. are introducing new assembly materials and challenging their engineers to develop new approaches to manufacturing. Consequently, GM, for instance, is using more aluminum and aluminum extrusions because engineers find them resilient, easy to work with and more corrosion-resistant than low-carbon steel. It uses extruded aluminum for frame rails, sheet aluminum for body panels and complex aluminum castings as substitutes for multicomponent assemblies that require assembly into a large unit.
A Forbes reporter discovered that the new full-size luxury Cadillac CT6 weighs less than a BMW 5 series model because it uses a multimaterial approach that maximizes aluminum solutions in critical structures to optimize lightweighting. In addition, GM engineers have developed a welding tip that can handle steel-to-aluminum welding. That’s a breakthrough since welding aluminum and steel together is difficult, reflecting the big difference in temperature required to melt each.
Numerous Aluminum Advantages
Aside from aluminum’s lighter weight, automakers favor aluminum extrusions for several other reasons. Aluminum extrusions offer solutions that increase vehicle safety as demonstrated by numerous vehicles in production today. This is a direct result of the energy absorption provided by well designed aluminum alloys. Another significant advantage is related to the recyclability of aluminum and the enhanced value in the material. Since the repair costs of aluminum-intensive vehicles have been documented as comparable to traditional steel-focused vehicles, this sustainability factor adds significant value to an aluminum-intensive vehicle at end-of-life.
The desire for lighter-weight vehicles won’t diminish any time soon, even as other materials such as magnesium gain increased attention. This demand explains why aluminum and aluminum extrusion producers such as Sapa are focusing their R&D centers on the automotive sector. Collaboration with their automotive customers to better focus on light-weighting solutions is what will drive innovation.
Dave Lukasak, PhD, is director of metallurgy and research at Sapa Extrusion North America, a producer of common alloy extruded aluminum products.