Magnesium, plastic and other lightweight materials allow engineers to boost fuel efficiency. With 75 percent of fuel consumption relating directly to vehicle weight, potential weight reductions that result in improved price-performance ratio continue to spur demand for new materials.
"Lightweight materials such as plastic are ideal to improve fuel efficiency and design flexibility without compromising on performance or safety," explains Sathyaraj Radhakrishnan, a research analyst at Frost & Sullivan Inc. (San Antonio). "Reduced tailpipe emissions and improved corrosion resistances are some of the other added benefits of lightweight materials.
"The automotive industry can expect an impressive 6 percent to 8 percent improvement in fuel usage with a mere 10 percent reduction in vehicle weight," adds Radhakrishnan. "This translates into a reduction of around 20 kilograms of carbon dioxide per kilogram of weight reduction over the vehicle's lifetime.
"Compared to traditional materials, plastic bumpers, engine covers and fuel tanks are 10.4 kilograms, 4.2 kilograms and 5 kilograms lighter, respectively. Lighter vehicles facilitate easier braking, reduced collision impact and superior driving experience."
Apart from plastic, magnesium alloy, which is two-thirds the density of aluminum and one-fourth that of iron and steel, and equally durable, is making inroads into the automotive industry. "With the engine comprising the bulk of a car's weight, magnesium's capacity to reduce engine block weight by 66 percent is a significant achievement," notes Radhakrishnan.
Magnesium is more expensive, but it is recyclable and offers unique advantages over steel and aluminum. For instance, magnesium provides design flexibility and is highly moldable into complex components that operate at elevated temperatures, which makes it attractive for under-the-hood applications.
Metal matrix composites are also promising lightweight materials, especially for powertrain and brake applications. Embedded silicon particles magnify the mechanical and wear properties, while the high thermal conductivity of the matrix increases the functionality of brake rotors. However, before metal matrix composites reach their full potential in the auto industry, Radhakrishnan says significant cost reductions in raw materials, fabrication methods and process improvements are essential.
