Magnesium auto parts formed by high pressure die casting are already common in cars and trucks, for steering wheels and other parts.
Using magnesium sheets to make auto parts could be a significant breakthrough for GM and eventually lead to much more magnesium in vehicles” said Dick Schultz, managing director of Ducker Worldwide and an expert on metals used in manufacturing.
GM is starting slow, using magnesium from sheet metal to make inner panels of doors and trunk lids.
“Magnesium is 75 percent lighter than steel and 33 percent lighter than aluminum” said GM engineer Paul Krajewski.
He said “it also costs three to four times as much as aluminum, but wider use will encourage magnesium sheet metal producers to make more, which will bring down the costs”.
“Magnesium will allow us to reduce the weight of certain sheet metal panels and thereby improve fuel efficiency and handling and overall performance,” Carter said in a telephone interview.
Manufacturers can stamp out steel auto parts at room temperature.
“The ultimate goal is to be able to one day stamp magnesium panels just like today we stamp steel panels at room temperature. We’re not there yet,” said Carter, but he added that magnesium sheet makers are working with new alloys that will allow the sheets to be formed at lower temperature.
“But those parts using magnesium” Schultz said.
Schultz said “the average passenger vehicle on the U.S. market has a weight of about 3,800 pounds, including 10 pounds from magnesium, steel makes up 2,100 pounds of the weight of that average vehicle, and aluminum makes up 343 pounds”.
“We found that if we control the way we heat the sheet metal blank before it goes into the hot forming tool, it makes a world of difference in how the panel looks, how fast it can be formed and how to avoid making panels that have defects in them,” said Carter.
“Aluminum has gotten much better through innovations. Magnesium is probably where aluminum was 25 years ago,” said Schultz.
“Some of the existing infrastructure for making magnesium sheet dates back to World War Two when it was made for airplanes,” said Krajewski. “We are now seeing an evolution of both the alloys and the material processing technology that can truly drive the costs down.”