The automotive industry is going through an important development phase to address major issues concerning users and the environment. One of the biggest challenges is to reduce the weight of automobiles to reduce fuel consumption. It is expected that a 10% reduction in curb weight can result in a 6%-8% reduction in fuel consumption.
Original equipment manufacturers (OEMs) are facing criticism from different government bodies and NGOs, as almost a quarter of all greenhouse gas (GHG) emissions are from road transport. This is directly related to the weight of automobiles and their fuel consumption. Currently under review, the controversial 2025 CAFE standards require automakers to deliver a fleet average of at least 54.5 mpg by 2025. Apart from that, increasing customer awareness, along with energy security issues, are expected to drive the need for alternate materials for automobiles. Since 2017, interest in using lightweight materials has surged by 11 percentage points, according to Assembly magazine’s “State of the Profession Survey.”
This paper is divided into two parts, where the first is about the current applications using alternate materials and the second covers emerging applications with novel materials to approach the challenges.
Current state of the market:
To improve vehicle safety, noise and vibration, and fuel economy, automobile companies are constantly launching new materials, with most of them focusing on lightweighting. While cars of the past consisted of entirely steel-based products, manufacturers are now transitioning towards aluminum, the fastest-growing lightweight material, as well as magnesium and composite materials that deliver enhanced performance. The following figure represents the current materials being used for different automobile parts.
Vehicles today are predominantly steel structures, with some use of aluminum. The grades of steel range from mild (270 megapascal (Mpa) tensile strength) to hot-formed boron (1,500 Mpa plus tensile strength). Magnesium and polymer composites are used in some components, mostly on higher-end vehicles. The proportion of different composites in an automobile is listed in Figure 2.
Figure 2 demonstrates that the percentage of steel is higher compared to other composites. However, the automotive lightweight materials market is expected to grow at a CAGR of 7.4% from 2019 to 2027, and the market size is projected to grow from USD 89.1 billion in 2019 to USD 157.7 billion by 2027.
The key players in the automotive lightweight material market are BASF SE (Germany), Covestro AG (Germany), LyondellBasell Industries Holdings BV (Netherlands), Toray Industries Inc. (Japan), ArcelorMittal (Luxembourg), Thyssenkrupp AG (Germany), Novelis Inc. (US), and the Alcoa Corporation (US). At present, aluminum is popular with more than three-fourths (82%) of those assemblers. Other automotive lightweight materials in demand include plastics (53%), carbon-fiber composites (29%), high-strength steel (29%) and magnesium (11%). With the current challenges auto OEMs are facing, the industry is expected to shift the focus towards alternative materials to reduce the weight of automobiles for a better future.
Composites:
OEMs might have found an alternative material lighter than steel to reduce the weight of automobiles. OEMs are considering composites to replace steel and aluminium due to their properties:
- 10x stronger than steel
- 8x stronger than aluminium
- Very light compared to both steel and aluminium
Current alternate lightweight materials:
Ford is using natural fiber–reinforced composites to reduce vehicle weight. Cellulose tree fibers are used in the armrests of the Lincoln MKX mid-size SUV, while rice hulls and wheat are used to reinforce plastics and storage bins.
3M has developed hollow glass microspheres called “glass bubbles” that are engineered from water-resistant, chemically stable soda-lime borosilicate glass. It helps reduce the composite weight by up to 40%. It can be used as filler in sheet or bulk molded composites.
Tata Steel has launched an alternative for current flooring and sidewall material for buses and trailers. Coretinium is an optimized polypropylene honeycomb core used to lighten the weight of floors and sidewalls. Currently, it is used in the EU region for commercial vehicles.
SABIC, a chemical manufacturing company, launched a fiber-reinforced thermoplastic composite bulkhead to replace the traditional panels made of metal and thermoset materials. It is expected to have a 35% mass reduction compared to the existing metals. The bulkhead is made of UDMAX tape woven by Setex.
DSM Engineering Plastics developed EcoPaXX PA 410, a bio-based polyamide used in the crankshaft cover on Volkwagen’s MDB-4 TDI diesel engines.
Cadillac CT6 uses carbon fiber-reinforced plastic (CFRP) to lighten the weight of the body. Parts made of CFRP such as the hood, splitter, and wheel spats are super lightweight, imparting high performance and fuel efficiency as well as greater traction at high speeds.
BASF, in partnership with Magna and Ford, developed a carbon-fiber composite grill opening reinforcement. It was used in the 2016 Ford Shelby GT350 Mustang. The material is 24% lighter than the traditional metal. BASF’s Acrodur is a water-based, low-emission binder that strengthens the natural fibers to create a sustainable, stable, and lightweight solution for car roof frames. It was used in the Mercedes Benz E class.
Conclusion
As is evident, there are many unique challenges for transitioning to new materials across the automotive industry. However, the push toward these materials is strong: lightweighting is an effective method to meet coming CAFE standards and other restrictions. Composites will continue to be a tool with which the industry will meet rising challenges.
