hello,

this is my first post on this site so i hope it's in the correct area...

i've got a possible project involving AZ31B magnesium which i understand to be a fairly common grade of magnesium. and from what i've read it is still flammable. does anyone have any experience with this material. i'll be cutting 1/4" plate (the end result being a bicycle sprocket). any info would be appreciated.

thanks --phil

Have a Puple K Fire Extinguisher nearby. ABC extinguisher's will not put out this fire. If you pour water to it umm well Kaboom! We machined some of this a couple years ago at our shop and if I remember correctly we cut it at high rpm's, low feedrate, and dry. No coolant. I would confirm with someone else for speed and feed but I am positive about the fire risk. Purple K extinguisher's are not cheap either FYI.

havn't done it in years and I don't know of any fire extinguisher that will put it out (and I've seen several firemen try to before), but maybe this purple k stuff is magic. But here is what I did:

have a container of sand on wheels nearby.

have thick gloves and welding shades handy

Get some tongs

make your fixturing in a vise or some other easily realesable fixturing (you will be under a little pressure! so K.I.S.S. is the way to go)

Now IF it lights up you can remove it and put it in the sand wheel it outside and let it burn baby! :D

on the machining side dont know the speeds and feeds but the machinist handbook was where i got that info. So its accurate.

fireman was right on NO WATER and machine it dry. water will attack the metal and so will most coolants.

Use a vacuum rig in some way to get the airborn chips (can you say mess?) these chips will float everywhere it makes a real mess.

Realisticaly you would have to be a true idiot to light this stuff up. its usually the chips that cause the problems or once you bury a cutter and don't stop it fast enough. If your experienced in dry cutting aluminum you should be ok. If you consistantly melt aluminum while machining it dry YOU should probably look for another metal to play with.

have fun.


Ps: I purposly lit this stuff up in a fake fixture for proof of concept (I don't recomend this to you ) I am used to lighting this stuff up though (Glamous :D). So I know the sand thing is the way to go.

by the way some city's have regulations about machining this stuff in their territory. So make the sand bucket deep and dont' do it at night! (its realy realy bright)

Everytime I cut magnesium there will be one person (most likely wearing a tie) that will light the suff up "kids will be kids" try 1/2 spot drill 1500 rpm 2oo sfm 7.5 ipm .005 ipr

I've been working with mag for 27 years and only once got it to light up. Boy when it burns it REALLY burns. Amazing that a metal can catch fire. Problem with getting it to burn is you need very high temps and very fine particles. You could hold a match to the edge of your 1/4" plate all day and it would never catch fire but put a blowtorch on a pile of very fine chips and it would go up like fireworks. The only way to put it out is to smother it ie, keep all oxygen from the flames. I used a dry extingusher when I had the fire but looking back I think sand would have worked better but you would need at least 50 pounds because the fire, even a small one, is explosive in nature. Meaning anything you try to put on it to smother the flames will be blown off. That is why you would need a lot of sand to provide ample weight thereby preventint the flame from blowing the sand off the flame and increasing your chances of smothering the flame. I mill at 2000 rpm with a 4 flute 1/8" end mill and have no problems.

This is what you use for magnesium fires and powdered aluminum which can go up like magnesium in the right conditions.

"Class D Extinguishers:
Class D extinguishers contain a sodium chloride based dry chemical extinguishing agent. Heat from the fire coats the metal, excluding air and dissipating the heat from the burning metal, such as magnesium, sodium, potassium, sodium potassium alloys, uranium and powdered aluminum. They are specifically for use in areas where combustible metals are present." (From Associated Fire Protection)

Magnesium will even burn in 100% carbon dioxide gas; the the burning reaction uses the oxygen from the C02 and the residue that is left behind is pure carbon.

I may be thinking of some other material, but didnt they at one time machine mag under what amounted to a waterfall of oil? I have a hazy recall of such a pic in one of the old (20 some years back) machinist trade magazines, and I keep thinking the article was on production turning magnesium aircraft parts. Anyone know?


Tiger

thanks for the advice, the bucket-o-sand idea sounds great! i realize the possibility of fire is there but is it worth the risk? my little machine is only 6 months old and to be honest i'm a bit nervous about this project! i'll continue my research to try to calm my nerves.ha.
--phil

i dont know the specifics but alot of coolant type oils on the market either stain or attack magnisium. and water definitly does. If your machining for an aircraft company, chances are they have a specification or two that tells you what not to use. And usually coolant/water is on the "list"

Tooling for magnesium should have a negative rake angle and they should be run
at slighty higher speed and feed rates as for Aluminun, You can use the same type of
cutting fluids as that for Aluminum. There is A high potential for fire with magnesium
usually any dry type chemical fire extiguisher will work if the situation does arise.

a slight neg. rake will give somewhat of a better finish if your turning as for the fire only the chips have a chance of fire if you put a match or very high heat source comon sence a simple pre-caution is all you need and maybe a bucket of sand (for the guy with the tie and the zippo lighter)

Sorry, I can't add any real advice as to how to cut it, it's one of the few materials I have never cut. However, I can tell you that if you have a fire in the machine and you don't contain it right away, the machine is history.

I have seen the end result of a mag. fire gone bad on a slant bed lathe - it wasn't pretty. The machine was rebuilt, but required extensive re-grinding of the ways etc. All of the electronics were history (servos, controller, wiring, etc.)

That being said, there are plenty of companies in the world machining mag. so it's far from impossible - just be very aware of the fire risks going into the job and quote it considering those risks.

Chris

Phil,

Mag is actually pretty nice to work with. It cuts nice and crisp and chips fairly well. Its best to use good sharp carbide as it can be abrasive and wear out HSS tools fairly fast. I would disagree with the idea of negative rake tools.From my experiance,you want the tool to shear clean and not drag. It sounds like you'll be milling anyway so thats kind of a moot point. The biggest fire danger is from real fine chips and dust, especially the dust.Try to keep the machine clean as you go. The chips on and around the machine are what are likely to catch fire. The work isn't likely to ignite unless a chip fire gets it started. Keep the tools moving. Don't let them sit and rub on the part. If you have to use the slide hold make sure the tool is off the work or the spindle is off. I've milled and turned it over the past 12/15 years and the only time its sparked up on me is during a real fine finish bore pass on the lathe. I run it dry but sometimes brush on light cutting oil on a real light cut to keep the dust from igniting.

Dave

I don't have any personal experience with this material. I do know however about a Kerney-Trecker mill that burned up while machining this stuff. You do need to worrry!!!

I would not even consider the material if you work in a building with low ceilings or primarly built of flammable materials. Also if your work area is clutered with other machines where yoou don't have manageable safety zone around the mill I'd opt out also.

When metals burn they burn very very hot. Aluminum can easily melt steel when burning, in fact can be used to weld steel. Magnessium is really bad because it reacts with water. Something to think about because your body is made up of alot of water. In any event if a fire starts you have a very brief period of time where you can put it out before a considerable damage occurs.

Thanks
Dave


thanks for the advice, the bucket-o-sand idea sounds great! i realize the possibility of fire is there but is it worth the risk? my little machine is only 6 months old and to be honest i'm a bit nervous about this project! i'll continue my research to try to calm my nerves.ha.
--phil

Do any of you on this thread happen to be from MN?

would it be wise to use a shop vac to clear the chips as i cut? there is only one piece to do at this point with the possibility of more in the future.
thanks again for all the feedback! --phil

don't worry be happy and just cut it and don't worry about it the suff needs a major heat source to lite up

I agree with lakeside. Just use common sense and you'll be fine.

I've only had to mess with it once, and I think i know why you guys are saying no coolant, besides the incompatibilty. It mucked up our tank bad, we only had four fairly large castings to do, and had to drain and strain the tank twice (40 gallons or so). Nice little fine particles that clog up everything, what an absolute mess.

I just use lots of air to keep the chips clear and remeber to were a dust mask as the mag dust floats real well in the air. We use a shop vac however I would remind you of static electricity could be an isuue. As with the coolant, only a few coolants will work with mag. Oh did I mension the issue of it killing you coolant even if you do not use any on the cutting process itself, just the fines getting washed down the next time you use the coolant and at $800. bucks a drum that adds up fast. It is very abrasive on the machines as well as cutters. use coated carbide for best results and it machines easy.

And one last thing, the dust is what I fear the most like many other things the higher the oxegen the faster the burn like KA-BOOM!!

P.S. lots of insurance and a good fire exit for you and your work mates is a must.

John

We work with cutting zirconium tubing and have had several small fires in the scrap bin.
Zirconium is burning equal to magnesium and it can be difficult to put out so we have a few buckets of dry sand to pour on the fire.

Be safe not sorry

i machined magnesium for around twenty years on a daily basis. here are some tips. take heavy cuts and avoid fine finish cuts. do not let your tool rub or remaine stationary with the tool or work still in motion. do not use coolant, keep your machine clear of swarf. keep the swarf and chips well clear of the machine. its worth stopping on a regular basi to do this. if it flares, and it will very easily, do not use air or water to put it out. it has an afinity for oxigen. keep a tin or but of dry sand at hand. smothering it is the only way to put it out. if you keep your machine clean it will not start a major fire. use a brush and pan to pick it up and dump it in your bucket of sand.
if you have a large quantiy thar lights up it can cause a problem , as it light up every thing it comes in contact with, wood, plastics, wireing, ect. i could tell you a few tales of fires i had with it, some quite funny end results, other all mosr trajick, have fun it's a great matereal to use, it is 40% lighter than aluminium and in most cases stronger.

Is you project something that can be photoengraved or does it absolutely require machining?

jonblack

i believe it would require machining since the end result is a bicycle sprocket. i'm getting together some safeguards before i do 1 sample piece. i'll post the results...
--phil

I've machined a little bit of magnesium az31b, and had the same concerns as you when starting. I did have one little fire on my lathe. Sent a hot spark into a little pile of chips, and they went right up. Just keep your chips cleaned up and i don't think you have much to worry about.

Milling this stuff is very smooth and doesn't generate much heat. I've only used HSS cutters, and never had a problem.

Also, you might want to look at Alumicut for your cutting fluid. You can get a really nice finish with it.

P.S. All my mag projects have been sprockets as well. Take a look if you're interested: www.bubbabebumpin.com/sprocket1.htm Oh, and i don't suggest leaving a bed of chips around as seen in the pictures :nono:

while i'm a noob to machining, there must be some type of oil based coolant that would keep fine chips and dust under control. magnesium has been used for valve covers in autos for years, and bmw's new engines have a magnesium core, the water jacket is aluminum of course. so obviously motor oil doesn't affect it. it seems to me that some coolant would help keep those fine chips down rather than floating around.

Did I hear someone say zirconium.I've never ran magniseum but if its any thing like zirc 702/705 be very carful.We had 2 shops here in Tennessee burn while cutting it and weve had two pretty good fires that scorch the ceiling.But we make about 12,000 pound worth of zirc chip a year.So small amounts of magn. may not pose a problem.

word of caution careful with the sand it is notorious for drawing moisture and as mentioned before water and Mag don't play well together. dry powder is the only thing ive used or heard of we keep it in a 5 gallon bucket at the machine.
lots of cutting fluids made FOR magnesium now watch the reccomendations of high RPMs.... causes heat buildup i prefer low RPM's and 5-8 rake to break chips clean
easy material to machine and nothing that I am afraid of.

Josie, I am from MN.


I worked in a mag casting/machining facility for 7 years. Be very carefull. Definatly use coolant designed for mag. I have seen many fires ,class d extiguishers work, but let it sit for several hrs after the fire. All you can do is smother the fire. Do not use water we used to do a demo of what water does, all it will do is intesify the fire. If you are going to cut mag just be very carfull!! the coolant/oil acts as a fire preventative. we could never get the chips to burn after they had coolant on them.

I did some research on machining magnisium and the experts said "when you have a fire" not "if you have a fire". There is a ton of info on the web.

Many of their points were coverd in the discussion above, but to recap.

They recommend a clean machine, no old chips and aluminum are the worst. Some kind of reaction or maybe the aluminum will act as more fuel, I don't remember exactly.
Make large chips, dust is the worst.
Clean ALL the magnisium chips when finished and keep loose chips to a minimum while machining to limit any fire. Control the chips as they are being made, it's easier that way.
Cutting oil or dry. Most water soluble are a no no. They did refer to cutting submerged in oil.
The sand must be DRY and enough of it to bury any fire.
Do not store the chips in your shop, they are a fire waiting to burn.
Water gives up it's oxygen to hot magnisium freeing the hydrogen to make a small Hindenburg.

My neighbor anodizes magnisium as a business and they machine it often. They do a controlled burn in the parking lot when they finish machining. Fire control needs to be considered here as well.

If you have a lot of chips and need to recycle, you may need a special storage container.

Check your insurance policy when you are checking your local zoning codes.

hi,

Its my first time in here..How are you?

Do u have any idea where to find magnesium ceilings.
I am working in Auminum false ceilingsand looking for other products.

many thanks

Wassim meski - Syria

I have worked with mag in the aerospace industry for a lot of years. You are right AZ31B is one of the most common alloys. Sand or kitty litter will smother it but be advised if you have a pile of chips the size of a loaf of bread you may need a five gallon bucket of sand to put it out. The stuff cuts great and all the advice on positive rake,negative rake is opinion. Biggest thing I can tell you is that you must cut this stuff. you cant plow it around with dull tools like it is aluminum.