Scroungers watch out! Magnesium is more common than you might think.

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Kaleb

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I picked up a Swedish Johnsered chainsaw engine a while ago that I decided to tear down for parts. A piece of the centrifugal clutch was turning out to be very tough to remove, so I cut away alot of the half of the combined fuel tank and crankcase casting that was still attached.

It was light for it's size, and cut freely, so I thought it was plain old aluminium.

I cut the material away since I had decided to give it a thermal shock treatment to loosen the part and I didn't want all that metal acting as a heat sink. As I was heating it, part of the crankcase metal started to glow much brighter than the rest. The glow turned white and so bright that I could only look at it directly for a moment at a time. I then knew that it was almost certainly a magnesium alloy.

Water does not put it out, neither does CO2.

So be aware and test a slither of the material before using it with some sort of heat.
 

tel

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Thanks for reporting that Kaleb - something to watch out for indeed!
 

Omnimill

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I don't know about Magnesium but they say Titanium gives off UV light when it burns so you shouldn't look at it as it can damage your eyes.

Vic.
 

Tin Falcon

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magnesium fumes are not real good for you either.
I have welded both magnesium and titanium. Yes folks it can be done with mag we kept the vent opening as close as possible with ti it was pushed away a bit. this was tig and cover gas on the back side.
Don not try at home unless you have been trained in the safe working of this stuff.
Tin
 

BillC

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Silver nitrate is a good test for magnesium or alloys containing a large percentage of it. Dissolve a small amount of silver nitrate in distilled water and test it on a cleaned surface of the alloy. The amount of magnesium alloyed will increase with the blacker the surface spot is. Black is 100% magnesium when tested on light alloys. On bronze: - manganese bronze will be light gray, and if no color - tin bronze.

It is always good to test for magnesium before plunking a chunk of metal in a crucible of aluminum, and especially with a flame heated foundry.

BillC
 

compspecial

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Early model VW crankcases are well known for their high magnesium content. Another no-no for the melting pot!
Stew
 

cl350rr

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If you suspect you may wind up in this situation, keep a bucket of dry clean sand handy to handle the fire.
 

lordedmond

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I was taught that cement powder should be used on the pretext that if its a powder then it must be dry



Stuart
 

rake60

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Once magnesium is burning, you will not put the fire out.

The chance of a large solid mass of it going to flames is rare.
If you are machining magnesium, the fine stringer chips from a light cut will light up easily.
Best defensive attack is to scoop them up with a shovel and bury them in the back yard.
Dig them up in a few days and if they're still burning, bury them for a few more days.

I had a guy bring me an old Eclipse push lawn mower for repairs once.
I got the engine running like new, but there was a crack in the mower deck.
He asked me if I could braze it. NOT ON YOUR LIFE!
I happened to know from my antique engine collecting experience, that deck was magnesium.
I drilled a clean round hole at both ends of the crack to keep it from growing and left it at that.

There are a few manufacturers who used magnesium in push mower decks before the hazards
were understood. Another note to beware of.

Rick
 

Twmaster

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Magnesium is scary stuff once on fire. When I was in the fire service we had a special tank on our engines that held a chemical called 'purple K' was at the ready to put out flaming VWs.

 

rake60

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In my military days we were told Purple K would extinguish a magnesium fire.

Purple K is great for fires involving electronics.
It leaves no alkaline residue.

I'd test it in a controlled environment with a magnesium fire before recommending it.
I was present when it was tried once. Then we dug a hole and buried the burning magnesium.

I asked one of our fire school instructors about it and he just laughed.

He said, "Trust the military to build your confidence"

Rick


 

Captain Jerry

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BillC said:
Silver nitrate is a good test for magnesium or alloys containing a large percentage of it. Dissolve a small amount of silver nitrate in distilled water and test it on a cleaned surface of the alloy. The amount of magnesium alloyed will increase with the blacker the surface spot is. Black is 100% magnesium when tested on light alloys. On bronze: - manganese bronze will be light gray, and if no color - tin bronze.

It is always good to test for magnesium before plunking a chunk of metal in a crucible of aluminum, and especially with a flame heated foundry.

BillC
Does the swarf from manganese bronze present a fire hazard. I haven't worked with much bronze but I picked up a nice piece of 1" bar at the scrap yard last week. The outside surface was pretty beat up, but I only need a .825" finished diameter. As I turned it to size, it exuded oil so I thought it might be sintered bearing bronze but after I got through the outside, it stopped oozing oil and produced a fine, gritty swarf, like cast iron. The tool must have been dull because it left a hairy surface. I re-ground and honed the tool and the next cut left a fine smooth finish, but still produced a fine gritty swarf.

From this, can anyone identify the material. I'm not the best housekeeper so there is cast iron, aluminum, and stainless steel in the chip tray. Does the bronze of whatever origin present a fire hazard. I'm not really worried about fumes. When I'm working with new stuff, I breath through my eyes.

Jerry
 

Lakc

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MG is becoming very popular in automotive scrap these days. Valve covers and accessory brackets are two common uses. I once saw a technician taking a cutoff wheel to a Viper firewall, producing a shower of almost white sparks, I left the shop immiedately. :)

Scratch the oxide coat off any MG suspect part, and simply apply some vinegar, MG will bubble where AL wont.
 

BillC

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Captain Jerry said:
Does the swarf from manganese bronze present a fire hazard. I haven't worked with much bronze but I picked up a nice piece of 1" bar at the scrap yard last week. The outside surface was pretty beat up, but I only need a .825" finished diameter. As I turned it to size, it exuded oil so I thought it might be sintered bearing bronze but after I got through the outside, it stopped oozing oil and produced a fine, gritty swarf, like cast iron. The tool must have been dull because it left a hairy surface. I re-ground and honed the tool and the next cut left a fine smooth finish, but still produced a fine gritty swarf.

From this, can anyone identify the material. I'm not the best housekeeper so there is cast iron, aluminum, and stainless steel in the chip tray. Does the bronze of whatever origin present a fire hazard. I'm not really worried about fumes. When I'm working with new stuff, I breath through my eyes.

Jerry
No, manganese bronze will not sustain ignition. Sounds like the material you're working with is in fact sintered bronze. Most of the oil will be lost as the material becomes heated during the machine work. The oil is replaced in a vacuum chamber if it is to be used as intended - as oilite. Some other bearing bronze alloys will leave a very small curly chip similar to cast iron but not like sintered bronze which does not form an actual curled chip when magnified.

The only bronze that is hazardous due to fumes in beryllium copper - beryllium is deadly poison but is rarely found as scrap unless the scrapped article had some welding purpose or heavy duty electrical contacts. The contact points on the jaws of a spot welder are beryllium copper.

You are wise to be cautious with any unknown material - you never know and safety is first.

BillC
 

Scota4570

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A hobby I enjoy is converting chainsaws, blowers and wackers into RC airplane engines. Some of the crankcases are made of magnesium. It cuts like butter. I do a lot of final shaping on a disk sander with fresh new sandpaper. When you do that you must clean up the mess. The fine magnesium powder will ignite when you touch steel to the wheel and make a spark. It is real exciting. Be carefull.
 

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