Image credits: Havount, et al

The Race Toward Lightweighting

By Alejandro Enríquez | Wed, 07/07/2021 - 11:37

Weight is key for vehicle efficiency and performance. Both elements have been hot topics for decades but are now paired with the concept of sustainability. While it might still be possible to advance the performance, experts weigh in on the importance of doing so while keeping a sustainable mindset.

The US Environmental Protection Agency reported that in 2018 the average car weighed 1.85 ton, of which 55 percent is cast iron and steel, 11 percent is plastic, 9 percent aluminum alloys, 7 percent rubber, 3 percent glass, 1 percent non-ferrous alloys and 14 percent represents other materials, according to researchers. This has not changed that much since 1975. "The key to improving fuel economy is weight reduction: the smaller a vehicle is, the less power it requires to accelerate and the less energy to maintain a fixed speed,” wrote Frank Field and Joel Clark for MIT Technology Review back in 1997.

While weight has remained mostly unaltered, vehicles have changed. Cars today have more sophisticated safety features including ABS systems, airbags and other systems that only add up to the vehicle’s weight. If weight were to increase, so would fuel consumption. Moreover, ambitious goals toward electrification require lighter materials to balance heavy battery cells or hybrid powertrains. The more the vehicle weights, the more energy is required and the more batteries need to be installed, which again increases the weight of the vehicle. The vicious cycle needs to be broken if electrification is to become a mainstream reality.

Alternative Materials for Body Applications

For decades, steel and metal alloys were automakers’ materials of choice to form the body of the vehicle. Academics agree that steel is a time-tested material that due to its performance and, most importantly, cost, remains one of the preferred options for automakers to use for the most part of the vehicle’s body. To replace steel, materials must deliver high strength, energy intensity or the ability to absorb impact, manufacturability, minimum weight, corrosion resistance and maintainability, according to the paper “Modern materials for automotive industry,” published by Havorun et al on the Journal of Engineering Sciences.

MIT researches point out that the vehicle's body only accounts for approximately one third of the vehicle's weight. However, “for every 10 pounds saved by reducing the weight of the body, another 10 pounds can be saved by downsizing other parts of the car.” Havorun et al agree that alternative body materials must be low density, which would “reduce structural weight, resulting in substantial fuel savings and a lower carbon footprint in transportation and material manipulation."

There have been key developments in alternative materials that meet the necessary conditions to replace steel. Aluminum car bodies have already reached mass production, although only for expensive models. According to researchers, premium brands tend to experiment with aluminum alloys, including Jaguar-Land Rover, Audi and BMW. "Thanks to aluminum, the car gets lighter, which increases speed and reduces CO2 and fuel consumption” said Havorun et al. Aluminum can weigh up to 30 percent less than cast iron. Some aluminum alloys include materials like titanium and vanadium (TiAl3 and VAl6)to further enhancing its characteristics and reducing weight.

Another relevant material pushing lightweighting forward is carbon fiber. This material is particularly important for electric vehicles. BMW i3 EV model is largely made of carbon fiber, which according to Havorun et al, made it possible to increase the weight of the battery by 250-350kg. BMW called this material “carbon fiber-reinforced plastic.” The car body of this material is 50 percent lighter than steel and 30 percent lighter than aluminum.

Given the high cost of carbon fiber, it is currently used only in light sports vehicles, including Mexico’s VUHL. "ETXE Diseño, which is our engineering consulting firm founded in 2007, and Adman Leku, an advanced manufacturing company founded in 2013 and focused on carbon fiber components and complex sub-assemblies, work for VUHL and represent between 25 and 30 percent of our portfolio, respectively," said Guillermo Echeverría, Co-Founder of VUHL, in an interview with MBN.

Chemical Companies Supporting Lightweighting

Vehicles are becoming increasingly complex and leightweighting involves vehicle components, adhesives and coatings. OEMs have set ambitious sustainability goals, which involve more efficient and electrified vehicles. Consequently, the supply chain is also adapting. Throughout the years, MBN has documented how companies have tackled the lightweighting trend and how this has molded the agenda toward the future of the industry.

“We are working closely together with electric car OEMs and scientific research centers that use our materials for designing parts for these vehicles. With sustainability in mind, our coating business has developed a new self-repairing coating that eliminates the need for new paint to repair scratches on the car,” said to MBN Bjoern Eller, CFO of Bayer's material science business Covestro, back in 2016.

Chemical giants like DuPont, Evonik and LANXESS have continuously supported OEMs and Tier 1s’ lightweighting goals. “Evonik has two main drivers: saving weight and boosting efficiency. The company is now working on high-performance, lightweight materials to replace metal or rubber parts. By combining different polymer materials, weight is reduced and efficiency soars. Our solutions give customers the power to design commercially optimized vehicles with a perfect blend of multi-material systems," said Martin Toscano, Managing Director of Evonik Industries de Mexico.

In recent years, DuPont has also introduced its AHEAD strategy, through which the company will focus on advance hybrid, electric and autonomous driving. "Lightweighting, sustainability and comfort remain macro trends for combustion, hybrid and electric cars. We have a special program called AHEAD™ (Accelerating Hybrid-Electric Autonomous Driving) to address these challenges. Today, 30 percent of our global profit comes from AHEAD technology developments. This rate is similar in Mexico, since every vehicle in the US carries at least one auto part produced in Mexico," said Juan José Zaragoza, DuPont Latin America.

More recently, Pedro Bocajá, CEO México of LANXESS, confirmed that business decisions are also driven by lightweighting trends. "LANXESS’ goal toward 2040 is for all of our processes to be climate neutral, which is unprecedented in the chemical sector. We have also bought a company called Tepex, which is focused on fiberglass and other materials, to reduce the use of metal materials,” he told MBN. “Traditional materials like steel are being replaced with plastic and this has had numerous advantages. First among them is safety, since the vehicle can better absorb impact. Second, the vehicle is lighter and thus more efficient.”

Lightweighitng Among Tier 1, Tier 2 Suppliers

Different companies have confirmed how important weight reduction is, not only for vehicle efficiency but to keep them in business. "We are waiting to obtain the first patent for a camshaft manufactured through a foundry process of iron and steel. This will be a disruptive improvement for the engine. Combining both materials will result in less weight, lower costs and better injection-system performance. We need to work on our testing processes, to assure our clients that this component will provide better quality at a lower cost," said Mario Rodríguez, CEO of Arbomex, a leading Mexican Tier 1.

Even suppliers of industrial threats highlight the importance of reducing weight. Coats – a 200-year-old British thread company – is working on the development of carbon fiber-based composite materials like Synergex and Lattice, which can substitute metal and plastic in some vehicle components. “These composite materials come in handy when striving to meet OEMs’ vehicle weight objectives,” says Wenevir Maldonado Commercial Director Latin America North of Coats Mexico. Composite materials are lighter, more flexible and resistant than aluminum and can be woven through design software and thermoforming technology, thus reducing waste and weight.

Photo by:   Havount, et al
Alejandro Enríquez Alejandro Enríquez Journalist and Industry Analyst