Trying to cut Magnesium sets it on fire ! what can I do?

[sunshineyos]

Hi all,

I am trying to cat magnesium on my HAAS CNC machine and also on my RoboFil Wire EDM machine, but both are leading the Material to ignite itself.

Any suggestions on cutting magnesium? anyone already experienced it?

Thanks !

YoS.

[Alfadeko]

I've seen specialized magnesium mills, and all of them works with a lot of coolant (I supose you too), and the working zone has ignition sensors. In case of fire, a CO2 "cloud" dies off it.
These machines used to mechanize car gearbox enclosures in a factory here in Spain, until plastic ones replaces it.
I'm sorry about my English, but it's not my native Languaje. Ihope I have been helpful.

[MIKEL12]

Just posting to make sure that you know that magnesium and water makes fire.

When you heat magnesium and then put water on it you get hydrogen gas if i remember correctly from chemistry. But that was a long time ago

So solution could be, absolutely no water or very much water so that it never heats up.

[JimPAC]

Magnesium in the molten state is flammable when exposed to oxygen. The risk of fire is the main concern during cutting operation. High speed dry cutting is preferable in cutting magnesium alloys due to there being no extra part cleaning work required, the environmental benefits and the ecological concerns. However, fire ignition could happen when the cutting temperature is close to the melting point of magnesium during high speed cutting. An experimental study of the mean temperature on the flank face is has been done by several Gov contractors. In high speed cutting, the mean flank temperature is not likely to be less than that on the rake face, that is, the cutting temperature, as the undeformed chip thickness is very thin and of the same order of cutting edge radius. To measure the flank mean temperature, it is critically important to mount an artificial thermocouple properly in the workpiece. The mean flank temperatures in various cutting conditions are measured and the collected chips were examined under SEM to find the burn marks. It was found that below the mean flank temperature of 302 °C, there were no burn marks on the chips. This indicates that the mean flank temperature can reasonably be used to predict the occurrence of fire in high speed cutting of magnesium alloys.

I used to work for POLARCHIPS before I went to Vietnam. They manufactured ICEE (Slushy) machines for 7 ELEVEN, Qwik Shops and the like! They used magnesium and one of the 2nd shift lathe "operators" burnt the whole company to the ground. The fire department had to let it burn it self out!

Its the chips that are at risk! Wire I don't know about and haven't heard of many wire cutting applications for MAG.

Chips must not be allowed to accumulate or 911

Good Luck

[wildwestpat]

Hi Yos

Machining of magnesium and alloys with a high magnesium content are well know fire risks and need a proper fire risk assesment for both the storage of the scrap as well as the parts. The tools have extra clearances and well defined rakeangles to keep the cutting action clean with the least amount of friction. The use of slow feed rates and attention to removal of the swarf are also required to reduce the risk of fire taking hold. The use of a fire suppresant cutting oil is also a sensible precaution to not only keep the cutting temperature at the swarf/ tool tip below ignition temperature but also to act as a barrier to oxygen. I think silicon oil was used after a fire on a large mill caused by too enthusiastic removal of the outer skin of a large magnesium alloy casting. I can still recall the panic on the faces of the fire fighters after they had used foam to blanket the machine only to find that it continued to burn even more strongly - this incident was in the early 60's. Things have changed but the suggestion to keep the appropriate extinguiser to hand is well made - I would add check the escape routes as the smoke is also a problem if it does catch. You should try and find the appropriate coolant for magnesium as silicon oil has a very low surface tension and will creep further than the machine bed.

Good luck and stay safe as this is a well known fire hazard.

Pat

[Alfadeko]

I'm sorry, sometimes is better to shut up (I'm electronic, not "metalworker"). But I'm sure the mills I've seen use any liquid (special coolant, oil, silicon oil... I don't know), and CO2 in case of fire. And I heard something about an special tool to caught the magnesium chips.
Next time I will be more carefull before posting an answer.

[universalfab]

It's quite exciting and frustrating to see your workpeice go up in flames. I've machined and welded magnesium. I would definately recommend oil for machining , I used a heavy oil when I cut it and went slow taking my time. High speed machining magnesium I'm sure it's done, but I would'nt recommend someone that knows nothing about it doing it and that is probably not equiped to do it, be doing it. When I machined magnesium I used no special tools just patience and oil, sometimes depending on the job no oil or lubricant at all. Machining magnesium is just like messing with anything that has temperances and could cause major damage, take it easy, baby steps. I've never had chips light on fire, it sound like a nightmare, but I have had magnesium light on fire when I was welding it, just 1 time and I learned my lesson. Surely there is no comparison to a welding magnesium fire and a machining chip fire. Again be safe it's not worth becomming permanently disfigured and destroying your tooling.

[universalfab]

Don't know what your sorry for, there is nothing wrong with using a oil based coolant. Oil based coolant such as 88% water with 12% machining coolant concentrate. The mane thing is you just keep checking the temperature of your part and you'll be fine. Depending on the amount of machining done as I said before I use a heavy oil, mainly on drilling. For larger milling operations I use my flood coolant and occassionally feel my part and look at the chips that are being produced. So Alfadeko you might not be a metalworker, but you are correct.

Originally Posted by Alfadeko I'm sorry, sometimes is better to shut up (I'm electronic, not "metalworker"). But I'm sure the mills I've seen use any liquid (special coolant, oil, silicon oil... I don't know), and CO2 in case of fire. And I heard something about an special tool to caught the magnesium chips. Next time I will be more carefull before posting an answer.