magnesium speeds and feeds

[Bob W.]

I will be machining some mag parts dry and I am looking for a starting point for the speeds and feeds. Any advice? I wil be using MA Ford solid carbide end mills.

 

Thanks,

Bob

[DavidB]

It cuts like butter.

 

Have a class C fire Extinguisher handy.

[Bob W.]

Yeah, I have been reading up on machining mag and the things I have on hand are a class D extinguisher (metal fires), big bucket of sand, and a wood shop dust collection system. I was told NOT to use water based coolant but to run dry. Is mag like aluminum where it will gum up the cutting tool if run dry?

[GoetzInd]

mag is pretty gummy. We've done exstensive machining using waterbased collant w/o problems. use sharp tools. cuts like butta.

[DavidB]

When I cut Mag I cut it wet with water based coolant.

Keep it flooded I've not had a problem.

I have seen it go up when the guys cut it dry on the manual lathes.

 

Its only the light cuts that are of concern. The thin small swarf is the stuff that will light up if it gets hot.

[billystein]

hi bob

 

have you also heard, do not ream?

 

it has been a long time but think it still holds true. do not try to ream. I have used reamers in titanium. the carbide ones work ok. the hss and cobalt like to seize on the tool. the same thing is said to happen on mag. for ti i have shortened the flute length of the reamer to 1/4 " or so and ream thru with a little success. I have never tried this on mag.

 

billy

[Bob W.]

I guess I will go ahead and machine with coolant and use similar speeds and feeds to aluminum. Sound about right? Thanks for the input.

 

Bob

[Colin Gilchrist]

Hi Bob, similar to aluminum, but decrease your RPM by about 20%. David is right, it is the light cuts that are your major concern. Try to maintain a slightly heavier chip load to avoid the light cut problem. Absolutely do use a water based coolant and flood the heck out of it. You don't want heat to build up in the chips or the work piece.

 

I also like to stop frequently and remove the chips. Try not to let them pile up.

[Storkman]

Light the small chips with a lighter, they burn like sparklers...........remember to let go.

[john316]

.

 

I would be concerned about that dust collector too. The only chips it'll catch will be the dust and that's what burns the easiest.

 

Also, don't let your coolant sit overnight in the part. It'll dissolve and corrode the material.

 

.

[sharles]

Be sure to take some chips home and show your kids how you can make metal burn! Though, if I remember correctly, they left a heavy black residue. Still kind of cool watching it burn in a safe place.

[mcpgmr]

We machined mag dry with the same speeds and feeds for aluminum. Be careful! Coolant can attack mag and cause porosity and discoloration to develop on the surfaces. Depends on the customers specifications I guess. Our parts were for the Boeing CH-47 and coolant was not allowed. Now, should I tell you the story about the place I worked at when I was 16 that burned to the ground from a mag fire?

[Bob W.]

Thanks for the input. From what I have read the biggest safety assets in machining mag are common sense and managing the chips. I was told by the metal supplier to not use coolant which is where my idea for the dust collection system came from, to suck away the chips. I figured it would be safe since wood dust poses a serious fire risk as well so a good unit would be designed for handling flammable materials.

 

Sounds like coolant is okay so I will go that route. I have heard of the corrosion issues so I will get the parts dry quickly once removed from the machine. Thanks for the help.

 

Bob

[DavidB]

Mag rusts straight away, soon as its finished machining spray it with WD40.

Dont handle it with bear skin where cotton gloves. Its not danderous to handle just for the rust aspect.

 

We had parts get surface rust on them in the time it took to get the finished machined part off the machine and down to our spray booth for laquer spray.

[Surface]

Those with more experience would know more, but I think magnesium effects the coolant unless it is a coolant designed for that application.

[crazy^millman]

I have run it wet and done some pretty trick parts with it. I use to do model making when I 1st came to California. Coolant is fine, just blow off the coolant, and spray with WD-40 like suggested. Speeds and feeds were no different on a Fadal than Aluminum. 100 imp 10000 rpm no problem with 1/4 and smaller tools.

 

HTH

[DavidB]

Corrcet mag breaks done the PH in the water.

It makes the water hard.

 

You can get soluable oil specially for mag but

we just replaced the coolant after running the Mag.

[MotorCityMinion]

Head the fire warnings. I caught a lathe bed full of mag chips on fire. Somebody used the lathe and didn't clean out the chips. It went up very, very fast. Cleared out half the shop in under 2 minutes after I let loose with the fire extinguisher. Don't play with it or "show your kids". Before you know it , they'll be trying to light every piece of metal on fire.