help with machining magnesium

[mmckell]

hey guys

i have a job coming into the shop - they want me to machine 3mm off of 2-35mm diameter bosses on 6 magnesium brackets.
i'm thinking using aluminum cutting speeds and feeds with a pile of cutting fluid... ?
what do you think?
I've priced out the correct fire extinguisher. ($850.00)
I am doing this on our old Bridgeport style mill with a custom built enclosure to keep everything in one area and contained.

is there anything i'm forgetting?

I have our health and safety people looking into a proper way to dispose of the cuttings

thanks for any input
Mac

[dertsap]

Originally Posted by mmckell with a pile of cutting fluid... ? what do you think? :

treat it as you would aluminum in one sense but don't go to heavy on it and do it without the use of coolant , you may want to do some google research on the dangers of magnesium fires and water (or water soluble coolant)

[mmckell]

Originally Posted by dertsap treat it as you would aluminum in one sense but don't go to heavy on it and do it without the use of coolant , you may want to do some google research on the dangers of magnesium fires and water (or water soluble coolant)

THANKS FOR THE TIP!!
i did a bunch of checking on the net and i think i may go with a vortex spot cooler - sounds a little safer than oil coolants and it leaves me with nothing but chips to get rid of
i'll just need to add a cover to the top of my enclosure to contain all the air blown chips

thanks again
Mac

[universalfab]

Your going overboard, yeah sure if your not carefull it will catch fire and burn a whole straight through your mill, but a $850.00 fire extinguisher!! All you need are some big tongs so when that baby catch's fire you grab it and take it out of the shop and throw it in the dirt. Your taking such a little amount of material off you should'nt have any problems. If I were you I'd also stick to whatever coolant you've been using and having good luck with. Just flood it.

[Fegenbush]

Class D fire extinguisher = Bucket of sand

Seriously, that's all you need. A couple of galvanized pails from Home Depot and a big bag of sand should cost less than $20.

As far as coolant goes, if you're going to use any, make sure it contains no water. The make special stuff for magnesium, but kerosene should work, too.

[mmckell]

appreciate all the th input guys

as far as using the tongs and running - it's about 150 yards in any direction from my shop to outside - and i'm an old fat bugger

as far as the sand - very interesting - i'll pass that by our health and safety group but, i don't really want to throw sand all over my mill.

probably the largest reasons for taking all the precautions are
1 - we have about 150 people working in this factory that we need to worry
about
2 - these are 6 prototype brackets - one offs - don't ask what they cost
3 - I HAVE TO KEEP THE HEATH AND SAFETY PEOPLE HAPPY

those are the people that all this needs to be passed by before anything happens and i don't have a choice other than to play their game

thanks again all
Mac

[universalfab]

Originally Posted by Fegenbush Class D fire extinguisher = Bucket of sand Seriously, that's all you need. A couple of galvanized pails from Home Depot and a big bag of sand should cost less than $20. As far as coolant goes, if you're going to use any, make sure it contains no water. The make special stuff for magnesium, but kerosene should work, too.

That's not true, I've seen them use water and oil based coolants " I do this also" flooded and submerged and re-circulated for heavy machining of magnesium. Kerosene, 1 spark and you have a big fire on your hands. I know they do use kerosene as a cooling agent, but I don't use it. If your going to go down a straight petroleum road you mine as well use WD-40. For what he's doing he could use a spray bottle with WD-40 and be fine. Kerosene is pretty dam flamable, I don't know how it compares to ether, I think ether is more flamable. I myself personally have used oil based coolant, yeah it's oil based coolant but you mix it with water. It's like a 1-10 ratio, 1 part coolant + 10 parts water, 100's if not more coolants are exactly like that.

[pauluk]

Hi
make sure you use a sharp tool ones for aluminium should be fine and don't take very light cuts. it catches fire when the swarf is very fine or worse still almost a dust and the tool is rubbing more than cutting. i do keep a dry powder fire exinguisher handy when i am machining magnesum but have never needed it so far. you should not have a problem machining dry just don't go mad on feeds and speeds and dont let the tool rub at all. good luck

Paul

[universalfab]

Just use a 2 flute endmill and it's fine even if you do take fairly lite cuts if you use a 2 flute endmill. Where it get dangerous is when your precision grinding this stuff, always use the same abrasives for magnesium. That really goes for most abrasives in general anyway, but special precaution with magnesium is to never mix up your abrasives you use on steel, aluminum and etc. etc. with magnesium. That is where explosions have ocurred.

[underthetire]

we just keep a box of metal-x close by. I'd use a micro drop spray mist set up, oil is ok with mag, and with those you so little oil anyway.

[mmckell]

Originally Posted by underthetire we just keep a box of metal-x close by. I'd use a micro drop spray mist set up, oil is ok with mag, and with those you so little oil anyway.

Metal-X??

[JamesG]

Mineral oil?