Magnesium for light weight?

[Chiefxxx]

Hello,

I am interested in how seriously magnesium is taken as a material for light-weighting. I am trying to find studies that compare mag against steel and also take into account scrap amounts produced during manufacture.

Would be very happy to receive any help

 

[BrianPetersen]

I have had a few motorcycles with magnesium valve covers and ignition-rotor covers ... non-structural stuff.

I've seen it used for the backing structure for automotive instrument panels and pedal-cluster pivot brackets.

The old original VW air-cooled Beetle had magnesium crankcases.

It is only practical to produce magnesium parts by die-casting in a neutral atmosphere, and it's darn near impossible to weld it, because oxygen has to be completely excluded. All magnesium casting fabrication plants require extremely specialized fire protection equipment because magnesium burns under water - it's really hard to put out a magnesium fire. Machining chips are extremely flammable.

My experience with magnesium has been that it's brittle. Never bends (yields in a ductile manner), it just bends up to a certain point (elastic modulus doesn't seem very high) and then goes snap.

 

[CoryPad]

For automobiles, magnesium is taken seriously for cost and mass savings. Studies can be found at IMA, magnesium parts producers, journal articles, and professional societies.

http://www.intlmag.org/

http://www.spartanlmp.com/

http://www.meridian-mag.com/

http://scholar.google.com/

http://www.scirus.com

http://www.sae.org

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[TVP]

Chiefxxx,

There is a great deal of interest in magnesium, mostly for automotive applications, but also for some aerospace applications. Worldwide usage has increased for over 10 years straight now, with almost all of the increase due to high pressure die castings or thixocast/molded parts for automotive and industrial (housings for power tools, computers, etc.) use. The federal governments in the USA, Canada, Germany, Japan, Australia, and China are all actively supporting research, development, and manufacturing of Mg-related items. I suggest you perform a keyword search for SAE Technical Papers at

http://www.sae.org

or visit some of the following websites:

http://www.dsmag.co.il/

http://www.magnesium-elektron.com/

http://www.szmt.de/typo3/index.php?id=29

http://www.am-technologies.com.au/

http://www.thixomat.com/

http://www.intlmag.org/

http://iweb.tms.org/forum/default.aspx?forumid=15

http://www.magnesium.com/w3/

http://magnesium.pnl.gov/

 

[GregLocock]

The problems with magnesium seem to outweigh its advantages, for production cars, at the moment. Fundamentally the difference between designing for Mg as opposed to Al is that Mg is just foamed Al, that is, the material properties are in proportion to its density, so often you don't see much of a weight advanatge.

In cases where Al has a clear advanatge over steel, you might seem some benefit in going to Mg, for instance if your thin walled castings have a minimum wall thickness set by casting technique rather than a strength or stiffness requirement.

I don't know what the relative energy is to make the material in the first place, and how succesfully it can be recycled.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[thruthefence]

Northrop built some experimental " buzz bomb " flying wings during WWII, I was told they were welded in a helium filled sealed chamber, the welder in a "space suit".

On the older Bell OH 58/206 helicopters, the tail boom was magnesium sheetmetal construction.

I believe the Hughes OH6/500 originally had some magnesium skins.

Beech Bonanzas & Baron series use magnesium skins for the elevators & ailerons to this day.

The minilites on my Lotus are magnesium, and sadly way past their prime, I'm afraid.

 

[CoryPad]

Compared with aluminium alloys, magnesium alloys have lower melting points, lower melting enthalpy, and do not attack steel dies. These factors lower production costs. Mg alloys currently have an economically positive recycling infrastructure.

For bending stiffness limited designs, the material index for minimum mass is E^0.5/[ρ]. Magnesium alloys have a 20 % advantage here.

 

[Chiefxxx]

Thanks guys,

Hey Cory, any mpre information on the economically positive recycling structure?

Thanks again!

 

[GregLocock]

By the way, I've been involved in using magnesium for parts 3 times. In all three cases it has not made the grade, being replaced by steel once, and aluminium twice.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[kchan711]

The BMW Z4's crankcase is made out of Magnesium, the first in the industry I believe. It provides approximately 24% weight reduction according to BMW's tech briefs. It's actually pretty neat how they do the casting. They drive an airtight ladle containing Magnesium, which is then loaded into a rapid casting station (you may have seen this on "Ultimate Factories" on the Speed Channel). It then rams/injects the metal directly into the mold, separates and racked for cooling. All automated (except the ladle driving). Something to look into.

Kyle Chandler

http://www.chiefengineering.net

 

[ornerynorsk]

There are engineering plastics that warrant serious consideration before switching to magnesium. You don't have quite the unique flammability problem, the manufacturing processes are "easier", and there are some corrosion advantages as well.

 

[GregLocock]

Yes, but they are rather spendy. In a non automotive application we used Ultem 40 (40% carbon fibre) as a magnesium substitute with good results. Our requirement there was strength/weight, with some restrictions on geometry.




Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Rob45]

The Ford Ranger compact pickup truck launched with a magnesium pedal hanger casting; sourced fortunately from foundries in both Italy and in southwestern Michigan - since the Michigan plant had the unfortunate habit of stacking finished castings near the furnace outlet...

My significant other at the time was the (Ford light truck) design group leader for clutches, etc., and we awakened one Sunday morning to the news on the radio that "a plant in SW Michigan is burning furiously, and the fire can't be extinguished..."

Magnesium is a fine material, but its manufacture requires a great deal of another commodity in apparent short supply: common sense.

 

[evelrod]

For those of us interested in super light wt stuff...AND...have waaaay too much money for our own good---

http://www.foxwebsitedesign.co.uk/3.html

Rod

 

[CoryPad]

Rod,

Pretty cool parts, thanks for the link.