General Motors Taking Further Weight-Reduction Steps with Magnesium
Updated February 1, 2017
Probably the hardest, but most effective, means of increasing fuel economy is to reduce weight. Automobile manufacturers have been working at this for years, resulting in the development of the unibody, the aluminum engine block, and more plastic parts in non-critical areas. Maintaining vehicle safety is, of course, still a major concern, which has kept lighter materials out of critical areas, such as the safety cage.
Faced with increasing demand and regulations on fuel economy, automobile manufacturers have been working on a number of weight-saving techniques in order to increase fuel economy, while maintaining the safety and rigidity that traditional steel components offer.
The industry standard steel components have one problem when it comes to fuel economy, which is weight. While different steel formulas have made it possible to reduce some of that weight, there are other materials that offer the same strength of steel, but with less weight. The only problem is that these other materials often require different processes.
Aluminum is one of those excellent materials, which was often found only in cast parts, and later, extruded aluminum parts. Recently, General Motors [GM] patented a new aluminum spot-welding process, making it possible for aluminum to be welded in more complex shapes, such as in the safety cage.
Magnesium is another light metal with an extensive automotive background, but has been limited to cast components such as engine mounts and steering wheels. GM’s R&D recently made another pioneering step into weight reduction using thermo-formed magnesium sheet metal.
The new magnesium panels are 96% magnesium, 3% aluminum, and 1% zinc. They are 75% lighter than steel, 60% lighter than titanium, and 33% lighter than aluminum.“Every gram of weight reduction matters when it comes to improving fuel economy,” said Greg Warden, GM executive director for global vehicle body engineering.
“Being able to replace heavier metals with one of the lightest will help us deliver better fuel economy,” Warden continued. GM estimates they could realize up to 12% increase in fuel economy by replacing 15% of the steel and aluminum weight with the new magnesium panels.
The new magnesium thermo-formed panels are three or four times more expensive, but as the technology improves, GM is expecting supplies to come down in price. GM’s R&D is still refining the thermo-forming process, hoping to work out a low-temperature process that will still produce a consistent product, which will also reduce costs on the manufacturing side.
One major hurdle of magnesium parts is corrosion, and with the addition of the 1% zinc, GM’s R&D believes they may have solved that issue. “Like all of our advanced material vehicle parts, we subjected the magnesium trunk lid to the most severe strength and corrosion tests we know of, and it passed with flying colors,” said Jon Carter, GM R&D metals researcher. “We expect it to perform extremely well even in the harshest environments.”