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GM testing industry-first thermal-forming process for lightweight magnesium sheet metal

23 October 2012

102312 Magnesium Photo Graphic
Trunk lid inner panel is the first use of GM process for magnesium sheet metal. Click to enlarge.

General Motors is testing an industry-first thermal-forming process and proprietary corrosion resistance treatment for lightweight magnesium sheet metal that will allow increased use of the high-strength alternative to steel and aluminum. Magnesium weighs 33% less than aluminum, 60% less than titanium, and 75% less than steel.

GM wants to expand its use of low-mass parts on vehicles around the world and will pursue licensing opportunities related to this novel technology. The goal is for suppliers to be able to use the process to provide significant amounts of magnesium sheet that will trim pounds from vehicle mass.

Using high-strength lightweight materials such as magnesium and aluminum is one of the most effective ways to improve vehicle fuel economy and driving performance.

—on Lauckner, GM chief technology officer and vice president of Global Research & Development

GM R&D recently announced an industry-first welding technology for aluminum, which is expected to enable more use of the metal on future vehicles. (Earlier post.)

Until now, automakers have struggled to make reliably strong and non-corroding magnesium sheet metal panels using traditional panel forming methods. GM’s patented process turns increases the heat on magnesium to 450 °Celsius (842 °F), allowing the material to be molded into precise, rigid shapes.

Using this process, GM developed a production-ready magnesium rear deck lid inner panel that withstood 77,000 robotic slams and 250-kilogram impact drops without any issues.

Die-cast magnesium has been used in a variety of parts ranging from steering wheels to engine cradles, but GM is the first to use thermal-formed magnesium sheet metal in structural applications, and it expects magnesium sheet applications to grow with additional materials and process improvements targeted at reducing cost.

The United States Automotive Materials Partnership estimates that by 2020, 350 pounds of magnesium will replace 500 pounds of steel and 130 pounds of aluminum per vehicle, an overall weight reduction of 15%. This weight savings would lead to a fuel savings of 9% to 12%.

On the production ready rear deck lid inner panel, GM can remove 1 kilogram (2.2 pounds) of weight compared to a steel deck lid inner panel.

Every gram of weight reduction matters when it comes to improving fuel economy. Being able to replace heavier metals with one of the lightest will help us deliver better fuel economy to customers around the world while also still providing the safety and durability they expect.

—Greg Warden, GM executive director for global vehicle body engineering

Automakers also have struggled to make magnesium corrosion resistant. GM’s proprietary treatment for thermal-formed magnesium resisted 10 consecutive weeks of 24-hour environmental tests involving salt spray, 100% humidity and extreme temperatures.

October 23, 2012 in Manufacturing, Materials, Weight reduction | Permalink | Comments (8) | TrackBack (0)

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Comments

Many lighter materials such as composites, magnesium-aluminum alloys etc can replace heavy steel auto parts, specially for lighter more efficient electrified longer lasting rust proof vehicles.

Eventually, one-tonne (or less) mid-size electrified vehicles will replace our current 2+ tonnes gas guzzlers.

magnesium burns, right?

with an electric spark
oh maybe we have the worlds larget arc welder

So do gasoline, tires, interior fabrics, refrigerant liquid, sound proofing materials, luggage, drivers and passengers etc.

Magnesium IS a highly flammable metal, but while it is easy to ignite when powdered or shaved into thin strips, it is difficult to ignite in mass or bulk. And even when in the form of strips, the autoignition temperature of magnesium is approximately 473 °C (746 K; 883 °F).

" autoignition temperature of magnesium is approximately 473 °C (746 K; 883 °F)"

So the takeaway here seems to be that if you're trapped in your gasmobile and the fuel goes up you'll be well toasted long before your door panels start to burn.

Hey folks, don't you remember the ever popular 'mag wheels' of yore? No fire issues as I remember.

Magnesium wheels had higher fatigue and corrosion problems.

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