Magnesium Machining

[cormigu]

hi Everybody,

there is any formula for calculate Magnesium (speed & feed)?

 

thx.

[Guest CNC Apps Guy 1]

HSS or Carbide?

 

NO water based coolant!.

 

http://g4tv.com/videos/48344/Its-An-Effin-Magnesium-Fire/

[cormigu]

Good video,we are using air & carbide.

 

thx.

[MotorCityMinion]

Expanding a bit on Jame's input here.

 

 

I caught a manual lathe on fire once. Someone turned some magnesium and did not remove the chips from the bed. I put CAT 40 tool in the chuck to turn the nose OD down some, got some red as usual, then all of the sudden POW, one of the fastest fires you've ever seen. Que the banjos.

[Bruce Caulley]

Depends on the % purity of the alloy as to how dangerous it is. I recently had some castings that were I think 93% magnesium and we had no problem machining just with water soluble coolant. We even were giving them a water rinse before dichromate. For a bit of fun we did light some swarf, but even fine RMR swarf in a small pile would not completely burn out and solid strips would self extinguish after burning a certain distance. I even tried wetting some swarf to see if it burnt any worse and it either wouldn't light or went out almost straight away. I have a feeling it would need to be closer to 96%-98% before it is really volatile. Doesn't mean you don't take precautions, just that it might not be as bad as you think.

 

Bruce

[Bob W.]

I machine a fair amount of mag and here are the things I have noticed. If you use standard coolant the mag will react with the coolant and cause the oil and water to separate. The coolant concentration will drop and start rusting your machine and the mag parts will be corroding before you get them out of the machine. This will happen over the course of a week. I use a coolant designed for mag (Blasocut BC-37mg) and it works great. You also need a class D (combustible metals) fire extinguisher and it needs to be right next to the machine. If a fire breaks out and you have more than 1 gallon of chips in the machine you have about 5 seconds to get it out before there is no hope and it is time to evacuate the shop.

 

Mag fires are caused by carelessness and letting chips build up in the machine. I will stop the machine mid program to clear chips to avoid a build up of more than a gallon or two. Also store them in a container with a lid in place. Leaving chips in the machine and accidentally running a cutter into a vise jaw is how machines/shops are destroyed. The raw material is hard to ignite and it is not a fire hazard. Mag needs to melt before it can be ignited.

 

As for speeds and feeds, I usually run mag with a chip load of 150% that of aluminum. The stuff really does machine like butter. Nice thick chips greatly increases the safety margin because they are harder to ignite.

[Bob W.]

I should also add that using air alone seems riskier than using water based coolant. A big pile of dry mag chips will be a lot easier to ignite than a big pile of wet chips. Water is the last thing you want once the fire is going, but it will help a great deal in preventing a fire from starting.

[cormigu]

thx guys for help me.

[jeff]

Just make sure your tooling is sharp!

If it's dull, it will want to rub, and make a spark.

Really bright flame.

Make sure you have the correct class of fire extinguisher next to the machine just in case, because if you don't... you better hope your insurance is up to date.

LOL!

[cormigu]

Oh yeah absolutely...

[Cad-Camr]

Had a bad thing happen back in the day. Used a water based coolant and it caused corrosion on the Mag. After plating we got orange peel. The shop lost big money. After that we stored in process parts submerged in Kerosene. Ya sounds crazy, the idea was storing parts in a oxygen free invironment. Probably a better way now, but it worked and we never had a fire.