Lightweight Trends Weigh Heavy on Aluminium Debate

Mon, 09/01/2014 - 13:48

What automotive industry experts all agree on is that, irrespective of the energy source, weight reduction will play a crucial role in reducing energy consumption. The race is on in the chemical industry to devise innovative solutions for the replacement of traditional metal components with plastic composites, but the solution with the most widespread application potential may well be another metal: aluminum. Aluminum is by no means a newcomer to the automotive industry as it has been used in cars for over a century, despite widespread uptake being slow to materialize.

As early as 1900, aluminum was being used as an alternative to steel, although sheet aluminum was, and remains, more expensive than steel. Cast aluminum brackets have historically been even costlier. From the outset, aluminum has been the preserve of the premium vehicle, with cars featuring sheet steel body panels manufactured for the masses, and those with aluminum body panels restricted to more exclusive lines. Modern vehicles that have benefited from aluminum incorporation have been the Audi A8, the Jaguar XJR, and the Tesla Model S, which are all luxury vehicles. Nonetheless, the prevalence of aluminum use in the automotive industry has steadily been increasing over the last two decades while the lightweight alternative to steel has been the focus of significant R&D investment. According to research released by the Washington DC- based Aluminum Association, aluminum can provide 5-7% fuel savings for every 10% of weight reduction when used to replace traditional steel components in vehicles. Aluminum also has a 20% smaller lifecycle CO2 footprint than steel. When aluminum structures are used in hybrid vehicles, 13.5% better fuel economy is observed, and aluminum-bodied diesel vehicles net a 13.1% saving. Lighter aluminum bodied vehicles also boost safety levels by ensuring shorter stopping distances.

According to a survey conducted by Ducker Worldwide on behalf of the Aluminum Association, more than 75% of pickup trucks produced in North America will be aluminum-bodied by 2025, with Ford, GM, and Fiat Chrysler predicted to be the biggest users of aluminum sheet over the next decade. This would undoubtedly mean big business for the aluminum market, with the body sheet aluminum industry currently valued at roughly US$300 million a year. If all cars were to go all aluminum by 2025, that market would leap to be worth over US$7.5 billion. The report findings show that Tesla, Mercedes-Benz, BMW, and Ford will all exceed average aluminum content by 2015. Pickup trucks by these OEMs will contain an average of 249kg of aluminum per vehicle, E segment sedans 248kg, SUVs 186kg, and minivans 180kg. The total North American aluminum consumption for light vehicle construction is expected to increase 28% by 2015, compared to figures recorded in 2012.

Due to ongoing cost barriers, increased aluminum use in cars has mostly been focused on substitutions for auto parts such as engine blocks, castings, and wheel rims. The reason for this is not only because of the expense related to the raw material cost, but also increased fabrication costs. The stages involved in assembling aluminum-bodied vehicles far outnumber those for the assembly of their steel-bodied counterparts. The industry’s current leader in terms of production of aluminum-bodied vehicles, and purveyor of the world’s first all-aluminum SUV, is Jaguar Land Rover. The company produces 95,000 all-aluminum bodied vehicles a year, including its leading Jaguar XJR  and Range Rover models, at its plant in Solihull, UK. A look at the complexities involved in the assembly processes highlights the reasons for the higher associated costs. Traditional processes for affixing aluminum sheeting to vehicle frames involve thousands of rivets and meters of adhesive, both of which are highly cost-intensive. Jaguar Land Rover is currently purchasing 353 million rivets a year, using 3,722 per Range Rover. Affixing all of these rivets requires meticulous checking and insertion processes, and any mistakes can lead to costly delays. Unlike some OEMs that closely safeguard assembly processes, Jaguar Land Rover has actually invited major competitors to its British plant to observe production of the all-aluminum Range Rover, the first all-aluminum SUV to be produced. Jaguar Land Rover hopes that cooperation among industry players will help to reduce the number and cost of complex processes involved in assembling aluminum bodies.

The first all-aluminum bodied mass-production vehicle, the Ford F-150, will go on sale at the end of 2014, and represents both a milestone and a risk for the US giant. The truck’s all aluminum body will reduce the weight of the 5,000lb (2267.9kg) F-series, Ford’s most profitable vehicle and the bestselling vehicle in the US, by 700lbs (317kg). The new F-150 features an aluminum cab and bed, affixed to a fully boxed steel frame, which has also seen its weight reduced by the use of high-strength steel. Ford is aiming to produce 650,000 of these vehicles a year, almost seven times as many as the vehicles produced by Jaguar Land Rover in its well-established UK plant. 2 million rivets a year will be purchased to assemble the truck. Of course, Ford benefits from the fact that it previously owned Jaguar Land Rover and played a significant role in devising the systems currently in use in the UK factory, arguably giving the OEM a head start on other mass volume producers.

Bearing in mind the challenges faced by the complexities of the assembly processes, other major OEMs will undoubtedly be observing the success or failure of the F-150 closely. Should Ford pull off the all-aluminum feat hitch-free, other car-makers are certain to follow suit. The extent to which aluminum bodies will be brought to the mass market in the near future is uncertain. However, Ford has already demonstrated how the knowledge gained from the development of the F-150 can be applied to other models by presenting its Ford Lightweight Concept Fusion vehicle in June 2014. The Concept Fusion showcased a 25% weight reduction making it as light as the compact Fiesta, by reducing the weight of the 2013 Fusion, which weighs in at 3,431lb (1556kg), by 800lb (362.8kg). The Lightweight Concept Fusion features a 1.0l, 3-cylinder EcoBoost engine, with 30% of the weight savings coming from the suspension and 35% from the interior and the glass. The impressive weight reduction was achieved with a mix of aluminum, ultra-high-strength steels, magnesium, and carbon fibers.

However, for the time being at least, the expenses involved in such innovations make them commercially unviable for mass-market vehicles like the Fusion. While OEMs scramble to find ways to utilize aluminum to its full potential, longtime supporters of steel may also be making headway. The World Steel Association’s automotive division, World Auto Steel, is pushing the benefits of the UltraLight Steel Auto Body (ULSAB), with strong support from Porsche. In a joint project, the OEM and the association revealed that an ULSAB structure has been assembled, weighed, and proven to be lightweight, structurally sound, safe, executable, and affordable. According to the study, the ULSAB structure offers 25% weight savings at no extra cost, an 80% improvement in torsional rigidity, 52% improvement in bending rigidity, and a 58% improvement in first body mode, as well as meeting all mandated crash requirements. Perhaps the ultimate lightweight vehicle of the future will include elements of all technologies currently being developed. What is clear is that industry-wide collaboration, along with bravery on the part of those currently holding executable innovations, will bring advances to benefit the industry, the consumer, and the environment.