O\T Magnesium

[Kevin Goddard]

We have a job coming up to do some mill work on magnesium castings. We have never worked with mag. before and I am concerned about fire issues. I do not know its composition yet but it is alloyed. Any experiences or thoughts? Coolants, special fire extinguishers, insurance.

[Keith Graydon]

THere is a dry chemical supressant for Magnesium. We used to have soome here in the shop. it is gone now. Make sure you get some. It is called Metl-x powder.

Magnesium has a really high machinability index. kinda nice to work with.

 

HTH

-KLG

[chris m]

Fire is a serious issue there; you are right to be concerned. I would consult Kidde or someone like that about the availability of fire extinguishers.

 

Is the job worth the possible damage or destruction of machine tools and the risks to employees? Burning the building down for a $10,000 job doesn't sound like a good trade-off.

 

C

[jeff]

Don't let them scare ya Kevin,

I have a recurring magnesium job that we do about twice a year.

I love machining the stuff.

You have to have a special class of fire extinguisher (I believe a class d).

Other than that the only bad point about it is that the chemicals in mag. will break down your coolant.

If you talk to coolant reps, they won't suggest that you use your everyday coolant on magnesium because of fire issues,they have a special coolant for that.

We don't but that special crap and just use the hangsterfers s500.

My advice: Buy a couple fire extinguishers and start hoggin!!!!

Have fun.

[Jim Whipple]

Another issue that no one has mentioned yet is the size of the chips...smaller chips burn better than large chips!

Other than that it machines a lot like t356 Alum

Jim

[mikee]

One big thing. keep sweeping the chips up and away from the machine, and put them in a covered trash can for mag ONLY. IF MAG CATCHES FIRE YOU DONT HAVE TIME TO THINK !!. It burns very fast an HOT! We always cut it dry, and always cut a chip, no fine cuts.

 

mikee

[gcode]

You should also check with your insurance company.

Many machineshop policies prohibit machining

magnesium.

Keep the chips wet, clear them from the machine often and don't let anyone smoke near the machine or the chips.

Fine feathery chips like those created by a light

flycuts can be set off by a cigarette spark

 

[ 11-14-2002, 01:21 PM: Message edited by: gcode ]

[Elad]

We worked a lot with magnesium.

i have few tips :

1. always work dry!!

2. if the chips burn,it is very hot,but is doesn't burn high and the flames are very very small.don't panic and don't use the fire-extinguisher immediantly,and let it burn untill it finish.the chemical inside the fire-extinguisher is ver very bad for the x,y,z axis.(don't know the word in english but i mean it's bad for the things that your axis moves on)

3.use very sharp tool.we used special diamond tools ,if the tools are not sharp,more chance for fire.

have a bucket with sand,better than chemicals for your machine.

4. pray. ( it's a joke.don't worry,it is a great material)

 

[ 11-14-2002, 01:50 PM: Message edited by: elad ]

[jeff]

Elad,

Why always work dry?

I'm curious.

[Elad]

if there will be a flame,and a water will touch it,it will become a hydrogen,and there will be explosion.and a huge one!it is very dangerous!!

smoking in the area is forbidden!and don't use coolant!

[Guest CNC Apps Guy 1]

From my experience with Mag, using Hangsterfers Cutting Oil worked better than dry cutting. You ABSOLUTELY POSITIVELY DO NOT want to use ANYTHING water based, because while cutting, the heat generated from the magnesium (I believe) combined with the water, generates hydrogen. Which by the way is highly explosive. Anybody seen the Vandenburg???? Need I say more?

 

JM2C

[Jim Whipple]

quote:

---

Anybody seen the Vandenburg???? Need I say more?

 

---

Hindenburg??

Jim

[Guest CNC Apps Guy 1]

DOH!!!!!!!

 

Thanks for the correction.

[STEELTHOM62]

I don't cut mag where I'm at now, but at my old shop we saved our cast iron chips in chip carts and kept them and a shovel by whatever machine was cutting mag.If a fire started you simply shoveled the cast iron onto the fire and if you were fast it worked real well for smothering the fire.Otherwise you got the hell outta there.

[Kevin Goddard]

Now I am worried. Thanks for your input.

[Bullines]

Ah, memories of grade 11 chemistry class...

 

When water comes in contact with burning magnesium, stand back. The magnesium essentially rips the water molecules apart so quickly and violently that huge amounts of energy are released in a very short period of time. You get:

 

Magnesium + Water --> Magnesium Hydroxide + Energy

 

or

 

Mg + H2O --> Mg(OH)2

 

Something to keep in mind.

[STEELTHOM62]

Kevin, also remember this, mag is cut in shops everyday.You don't have to be afraid of it, just respect it and I'm sure you'll be fine.

 

[L Hanft]

To balance Bullines formula......

 

Mg + HH0 = Mg(OH*OH) + 2H The hydrogen molecule is the devel in the mix... add a little oxygen from the room and Kaboom (course a heat/spark source is required) and don't under estimate static electricity as a spark source.

[L Hanft]

Should be Mg + 2(H2O) = Mg(OH)2 + 2H + Heat of reaction

[L Hanft]

Just trying to get to 50 posts...... not.

 

Your casting is probably a Magnesium alloy... although some of the properties of Magnesium are retained the alloying process has probably changed the chemical properties of the material. It is certaintly not as reactive, and depending on the alloy it could be difficult to ignite. Without knowing the alloy caution is always the best choice.

[Bullines]

quote:

---

To balance Bullines formula......

---

Thanks. It's been a while

[SVO]

I have seen the Magnesium react with our water based coolant and it literally started to etch itself into the machine table. Very bad. Now we cut it dry and keep the chips clear, and keep the handy dandy class D fire extinguisher close by. We don't cut enough of it to warrant major process changes. Just like any other operation, work smart and pay attention.

Dan

[McRae]

If you are having a little bit of a stomach ache, drink the Milk of Magnesia - the leftover from the catastrophy...

[mark l]

I used to work at a place that machined Mag. we always used regular cinncinati milicron coolant, we really flooded the parts and never ever seen a fire, I ran the tool into the fixture one day, oops, I seen sparks but with the flooding of coolant no fire, by the way I had this happen several times, it's a wonder they didn't fire me. But however we got a multi-spindle drill machine in from another plant that was machining the mag dry and they said fires was a BIG problem, and sure enough I was changing a drill and let it slip, there was a pile of chips under the drills, JUST THE SPARK FROM THE DRILL BREAKING set the chips off, just like the sparklers you buy your kids on the 4th of July. So to make a long story short, my experience is KEEPING IT FLOODED IS A GOOD THING, DRY CHIPS IS A BAD THING.

[mark l]

Also like someone else said, the mag mixed with water does produce hydrogen, so you do want to make sure the machine is well ventilated, you don't want to run this on any machine that might have pockets that the hydrogen could get trapped in.