In a recent in-depth interview, MagnesiumCom President Marks Lisnanskis discusses the characteristics and superior advantages of forged aluminum and magnesium wheels for improved performance and safety considerations in luxury and sport vehicle applications.
Mr. Lisnanskis explained that wheel weight, a key component of unsprung vehicle mass, is critically important to overall performance.
In a ground vehicle with a suspension, the unsprung weight (or the unsprung mass) is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them, rather than supported by the suspension. (Wikipedia) In other words, the unsprung weight includes wheels and tires, brake assemblies, the rear axle assembly, and other structural members not supported by the springs.
According to Mr. Lisnanskis, the generally accepted rule of thumb for predicting performance benefits from sprung vs. unsprung weight reduction is a factor of about 4:1—reducing one pound of unsprung mass yields a four-fold advantage in vehicle performance parameters. For example, large diameter (20”-22”) forged magnesium wheels increase the weight advantage over aluminum by eliminating an average 70-75 pounds of unsprung mass, while at the same time providing the same acceleration time and braking distance benefits that would accrue by eliminating 250-300 pounds from the vehicle’s engine, chassis or passenger compartment.
Mr. Lisnanskis adds that magnesium forged wheels are “approximately 50% lighter than regular aluminum cast wheels, sustaining equal loads -- with better characteristics which yield shorter, life-saving braking distances” and which allow for shorter acceleration, reduced fuel consumption and a longer-lived vehicle suspension.
The forged magnesium wheel manufacturing process is critical to the strength of the finished wheel, which is produced by applying extremely high pressures to the base material in a contained three-dimensional die. During the process, the forged wheel blanks, or “pre-forms,” undergo changes in their metallurgical grain structure which add to their strength and quality/characteristics -- forging gives the magnesium a more highly organized and aligned grain structure (versus that found in standard cast wheels). One result is significantly higher material strength, important whereas the wheels encounter load challenges from surface hazards or from lateral and other loading generated by the vehicle’s own inertia. Additionally, magnesium’s high damping factor allows improved absorption of road vibrations and impacts (by 100x better) compared to aluminum’s. Modern computer-aided modeling techniques allow the wheel manufacturer and the automaker to collaborate on a specific forged wheel geometry and design for optimal vehicle strength and safety.
Mr. Lisnanskis also shed light on the introduction of one-piece forged magnesium wheels for street use in North America. The wheels are at least 20% lighter than forged aluminum and offer greater safety, such as somewhat shorter stopping distance, and increased performance benefits, he says. “The U.S. wheel market is quite formidable, and we intend to supply a smaller but very important segment of the 100+ million vehicle market. . .(with) best-in-class wheels that automakers can offer as an option on new vehicles, and consumers can add to their present vehicles,” he stated.
SMW Engineering is a global leader in developing forged magnesium wheels, and Mr. Lisnanskis says SMW engineers acknowledge another important feature of forged wheels over conventional, cast wheels: the integrity of the wheel’s surface finish. Most available forged wheel styles and finishes are enhanced by the density and uniformity of their surfaces. This is especially important on high-end, ‘bright wheel’ vehicle applications where high-quality aesthetics are desired but not always readily available due to cost and environmental considerations. Forged and properly coated/polished wheels add a distinctive element to a vehicle’s overall appearance; and the new technology available at SMW now allows for 10-year guarantee on the forged magnesium wheels.
With technological advances in forging magnesium wheels come new applications in production, design and end use. SMW Engineering is seeing an increased presence of magnesium wheels in the automotive and motorcycle racing venues and among enthusiasts, where these wheels provide efficient weight reduction, better handling and superior performance. Luxury car, motorcycle and bicycle manufacturers are also meeting greater consumer demand for high-performance magnesium wheels, often with exclusive designs and specialty coatings. SMW Engineering has been producing MotoGP, Superbike and Formula One competition wheels for many years, along with other championship classes. The wheels are forged in Russia and then machined and finished in Italy.
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