Subject: Identifying aluminum vs. magnesium

From: David Baggaley <[email-masked]>
Date: 12 May 1996 15:45:21 GMT

Can anyone recommend a quick and dirty method of distinguishing these metals?
I have an old circular saw that seems unusually light for it's size and I'm
curious what it's made of. 

I know magnesium burns, but I'm not that curious.

Dave 

-- 
Dave Baggaley
Thunder Bay, Ontario
mailto:[email-masked]

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From: [email-masked] (Jonathan M. Elson)
Date: 15 May 1996 04:47:06 GMT

David Baggaley ([email-masked]) wrote:
: Can anyone recommend a quick and dirty method of distinguishing these metals?
: I have an old circular saw that seems unusually light for it's size and I'm
: curious what it's made of. 

: I know magnesium burns, but I'm not that curious.

Sure - that's how you test it.  File a tiny bit off a corner somewhere.
You don't need more than a few grains.  Light a propane torch, and sprinkle
the file dust into the flame.  If you see tiny but brilliant blue-white
sparkles flash in the flame, it is a flammable metal, ie. Mg or Ti.
Hmmm.. I wonder how safe it is to make power tools (with brush-type motors,
even!) with Magnesium housings.  A little short in the motor could be a
real experience.  I've seen a few VW microbuses light up, and it is
spectacular - like a 4th of July display when the firemen put it out.
I don't know whether it is the engine block or the transaxle that is Mg,
but one of them clearly is!

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From: C++ Freak <[email-masked]>
Date: 14 May 1996 11:06:20 GMT

Determine the specific mass by weighing it and then obtaining the volume by
immersing it in water. Mg has a s.g. of 1.74 and Al of 2.7, most alloys 2.6.
Titanium (another light and strong metal) is 4.5.

Another way might be cutting off a *small* piece and set fire to it by a torch.
When it emits a bright white light, it's Mg. When it only melts at dull red
glow it is Al. Otherwise it is titanium or steel.
But a circular saw is unlikely to be magnesium or aluminum, it is probably
steel (s.g. 7.8).
The light weight is just because of its thinness.

Klaas

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From: Roger Gibbs <[email-masked]>
Date: Thu, 16 May 1996 17:48:44 GMT

[email-masked] (Jonathan M. Elson) wrote:

>I don't know whether it is the engine block or the transaxle that is >Mg, but one of them clearly is!

PortaCable recently (last 2 years ?) introduced a line of circular saws whose housing is made of magnesium . The ads point out how light these saws are.  Evidently PC feels this is a safe practice ?  I don't know about VW microbuses, but I do recall that the Porsche 6 cylinder engine began as an aluminum casting (I am talking the main crankcase housing) then changed over to a magnesium casting to save weight in the late sixties.  They changed back to aluminum after only a year or two as I recall because the cost to produce the mag castings was higher and there was a durability or repair difficulty associated with the mag - I believe that the mag had a tendancy to exhibit dimensional instability so that round holes became ovals.  It was reported that once this metal movement occured, the crankcases could be remachined and would then be dimensional stable indefinately.

My Dad was a machinist and would bring home mag chips for us to play with.  Some were produced with cutting tools with a chip breaker (producing chips of mag) and some without a chip breaker (prducing long curling "strings" of mag up to about 2 feet in length.  Having first hand experience with burning mag, I have quite a respect for machinists who are able to reliably and safely machine this stuff.

Roger

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From: Gene Olson <[email-masked]>
Date: 17 May 1996 02:39:19 GMT

Bunch of Pyromaniacs running  around.

Magnesium turns black when subjected to acid.

-- 

 The Studios of Gene Olson and Chris Wilson - Working in Metals, Stone, 
Mixed Media
    8600 NE O'Dean Ave, Elk River MN 55330
   fax:  612-441-5846  Phone:  612-441-1563
 email:  [email-masked]    URL:  http://www.cris.com/~mettlewk/

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From: [email-masked] (Peter Brooks)
Date: 16 May 1996 18:15:31 GMT

That's the quick and easy test.  Take a small sliver off the metal and lay
a torch on it.  If it melts and balls up with no further ado, you probably
have an aluminum alloy.  If it starts to burn, it's magnesium.  Use a
*small* sliver for the least amount of drama.

Pete Brooks

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From: [email-masked] (Jim Shockey)
Date: 17 May 1996 07:30:02 -0700

>Bunch of Pyromaniacs running  around.

You say that like it's a bad thing!?  <g>

>Magnesium turns black when subjected to acid.

I've never used this method. Is muriatic of sufficient 
strength to give a clear indication? 

Thanks,

--jim			<[email-masked]>

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From: Roger Gibbs <[email-masked]>
Date: Thu, 16 May 1996 17:47:23 GMT

Roger

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From: Roger Gibbs <[email-masked]>
Date: Thu, 16 May 1996 17:38:32 GMT

Roger

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From: [email-masked] (Michael Edelman)
Date: 20 May 1996 19:16:10 GMT

Jonathan M. Elson ([email-masked]) wrote:
: David Baggaley ([email-masked]) wrote:
: : Can anyone recommend a quick and dirty method of distinguishing these metals?
: : I have an old circular saw that seems unusually light for it's size and I'm
: : curious what it's made of. 

: : I know magnesium burns, but I'm not that curious.

: Sure - that's how you test it.  File a tiny bit off a corner somewhere.
: You don't need more than a few grains.  Light a propane torch, and sprinkle
: the file dust into the flame.  If you see tiny but brilliant blue-white
: sparkles flash in the flame, it is a flammable metal, ie. Mg or Ti.

Aluminum burns quite well well finely divided, too.