Cutting aluminum w/carbide- chip welding problems

After a life time of cutting tool steel, I find myself cutting a lot of aluminum these days. I was trying to slot some ordinary 6061-T6 with a 1/4" carbide end mill, but the chips weld themselves and ball up on the cutter. I've tried a variety of feeds, speeds, and feeds, but have better results with HSS end mills. It's an open CNC bed mill, and the only coolant is a Kool-Mist. I know WD-40 works well on aluminum, but it would make a huge mess, and I'd have to stand there squirting it on the cutter. Suggestions?

Aluminium specific high helix endmill?

MattiJ said:

Aluminium specific high helix endmill?

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This plus an air blast to clear the chips from the cut.

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is the cutter coated ? …..if so with what? ………..is it sharp?

MushCreek said:

After a life time of cutting tool steel, I find myself cutting a lot of aluminum these days. I was trying to slot some ordinary 6061-T6 with a 1/4" carbide end mill, but the chips weld themselves and ball up on the cutter. I've tried a variety of feeds, speeds, and feeds, but have better results with HSS end mills. It's an open CNC bed mill, and the only coolant is a Kool-Mist. I know WD-40 works well on aluminum, but it would make a huge mess, and I'd have to stand there squirting it on the cutter. Suggestions?

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aluminum dont like dull end mills or end mills made for steel which are made dull like (less rake and clearance)
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often if you ease up depth of cut, sfpm and feed it wont get so hot to stick to flutes. some use oil at put along cutter path. mostly its having the right end mill made for aluminum thats sharp

Trico Microdrop lube system works well on aluminum. Maybe not equivalent to flood or through the tool coolant, but better than manual lubing.

If you have Kool-Mist you probably also have a Noga Mini-Cool Applicator or equivalent. So you have a way to get both a good cutting fluid and compressed air down into the cut. I imagine you have positioned the applicator so that the nozzle is blowing down into the slot with a generous air flow and modest amount of fluid? Doing so really helps blast the chips out of the cut and at the same time the fluid inhibits welding. Of the two it seems like the most important is evacuating the swarf.

Might be helpful to know your cutting parameters....


Denis

HuFlungDung said:

Trico Microdrop lube system works well on aluminum. Maybe not equivalent to flood or through the tool coolant, but better than manual lubing.

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Same just different brand, been running a acculube here for a long time and its great for these kinda jobs, mess wise its nothing more than wipe a light coating of oil off the vice jaws at the end of the day (the veg based oil goes gummy if left too long) but can't be stated enough how the micro drop systems really leave no oily residue more than say 2" from the cutter path and only then if you have been running the same cutter path for hours. Theres no noticeable smoke and all the swarf is dry to the touch. Set right and you need it a little on the richer side for aluminum your talking a couple of egg cup fulls of oil for a 8 hour shift at most.

2-flute TiCn coated or TiN. if you use any coatings containing aluminum, you'll likely get
chip welding .

Current cut parameters? For me; all the RPM the Machine has, .01" chipload, 1/2 diameter deep, 2 or 3 flute uncoated Tool. That will get you past your issue, but it's very conservative.

R

WD40 or a cheaper generic IS what you want. if youre moving just a lil material use it in spray mode, you don't have to sit there and douche it continuously. to move more matl use it with a brush. and once you stick some aluminum to the cutter regardless of hss or carbide, don't knock off the aluminum and try to use it in aluminum again, it will now stick 4x as quick. can still be used in steel tho if edge is not damaged.

another thing that has worked was to use a rag or brush with Crisco and rub it on the cutting path leaving a visible amount. stays there better than WD. forget this if you cant deal with messes, and clean well when done, or a week later the smell will gag you. it does work. would I do it again? no. have also used parrafin or candle wax. none of this is ideal, if I had a lot to do on an open mill id have the microdrop or acculube setup. I did have the kool mist setup, it was mediocre at best, and the Trico synthetic mist worked much better than the Kool Mist in it. breathed a lot of that stuff, have no ill effects so far but wished I hadn't done it.

Cutter is new, 4 flute, has a coating, but not sure what (dark gray). Microdrop would be great, but our department has a budget of $0 (it's hard to even get cutters). I slowed it way down and it has done better. but HSS works better so far. 1400 RPM, .001/tooth/revolution, .050 cuts. When I bury it it loads up and *SNAP*. WD-40would be great, but I have no way to dispense it without standing there all day. I think it would make a huge mess in the Kool Mist unit.

can you go 4000 rpm, 2 flute em, HSS, same doc and .004/rev? good god man, 0 budget is what it is, but if you cant get a couple $20 end mills to fuck with, youre pissing in the wind. do it, then push a lil more, and again, and again, I bet you can get where litlerob1 says you can. if the mill breaks, back off to the previous setting. doing 1 and 2 offs, the goal is the parts. doing 10000 pcs, the goal is the parts as quickly as possible. use what you got, but push a lil more each time you are successful, then back off a *unthair when it fails.

MushCreek said:

1400 RPM, .001/tooth/revolution, .050 cuts.

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1400 rpms on a .25 endmill is under 100sfm. That in and of itself should not cause a meltdown.

.001" per tooth. That's hardly a chip... Where is your heat going??? Into the chip, and then
beyond the chip thickness into the material.. Over and over again, and eventually you get a
melt down.

FEED IT!!!! Just like dry cutting steels, you want all that heat IN THE CHIP, and GONE!!!
You don't want to push the heat ahead of the cutter, you want to slice it off and toss it
into the chip pan..

If I don't touch any aluminum for a while, I find myself under feeding, its a different
animal than most steels..

Dig up some of ExKennas Ripper mill vids. 6061 dry, at stupid speeds.. The trick.. BIG chipload.
I'll link a vid I made.. I think I was feeding .018" a tooth at around 2000sfm, 6061.. Worked like
a champ.. The cutting part.. Avoiding HOT chips down the collar, not so much..

Just for fun some day, see how hard you can feed in aluminum.. Take a piece
of scrap and just keep upping the feed..

Another story.. Many moons ago when I first got to play with real machines.. Just to see what
it was capable of (Mazak FJV20).. Regular old 4 flute 1/2", .25" depth, .25 width (I think, it
was a long time ago).. Max revs 12k.. And just kept upping the feed. Maxed out at 706 or 708 ipm.
About .015 a tooth. The machine didn't have any more feed, so started backing down the revs while
keeping the max feed. Got down below 6k, .030 a tooth, then we got bored and went home.

I'm 99.9% sure, based on my own experiences, that a thicker chip will cure your melt down problems,
especially at such a low surface speed.

MushCreek said:

Cutter is new, 4 flute, has a coating, but not sure what (dark gray). Microdrop would be great, but our department has a budget of $0 (it's hard to even get cutters). I slowed it way down and it has done better. but HSS works better so far. 1400 RPM, .001/tooth/revolution, .050 cuts. ......

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Can I say everything wrong here.
Advice is ,no coat, 2 flute, more surface footage, higher chipload.
You can go way down and work but the problem here is not enough speed to make it work right.
I know it seems wrong but you have to put the peddle to the metal here.
You are sitting squarely in what most would consider no-mans land for AL.
Bob

MushCreek said:

Cutter is new, 4 flute, has a coating, but not sure what (dark gray). Microdrop would be great, but our department has a budget of $0 (it's hard to even get cutters). I slowed it way down and it has done better. but HSS works better so far. 1400 RPM, .001/tooth/revolution, .050 cuts. When I bury it it loads up and *SNAP*. WD-40would be great, but I have no way to dispense it without standing there all day. I think it would make a huge mess in the Kool Mist unit.

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These parameters are insane!!

Ditch the 4 fluter, and use a 2 or 3.

Rough estimate, at least 20x faster-everything.

Read post #10. Those are conservative numbers. DO IT no need for coolant or wd-40 or anything else. Just cut with those parameters dry.

(don't put food on your workpiece)

I made a box from sheet metal to enclose the vice so I could use flood coolant. Made a world of difference. Sheet metal was furnace duct flat sheets.

Tom

i just use some regular oil along cutter path with plastic squeeze bottle. dont need to continuously apply. why regular oil ? cause it dont leave a big mess and keeps the rust down to minimum.
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why use goo or sticky stuff going to be a big job cleaning up ?? just regular oil works ok. if you dont got any oil on table and vise its just going to get rusty anyway.
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also hand held metal cutting circular saw cuts way fast sfpm and chips are in the .0001" ipt range. why ? cause you cutting at 5000 sfpm if you dont want aluminum to stick to blade you cut light enough for blade to do its own cooling. at that sfpm the circular saw is its own fan moving air. i often cut 1/4" to 3/8" aluminum and steel like cutting plywood. the new metal cutting circular saws are literally 10 to 100 faster than older saws. compared to conventional feeds and speeds for aluminum it dont make sense and yet it works quite well
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many a router is machining aluminum at way fast sfpm and very light ipt feed. it works usually very good. but router cutter needs to be sharp.
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you ever used carbide inserts made for iron and steel on plastic ? usually work bad. if you use inserts made for aluminum normally they are uncoated and sharper rake and clearance often inserts honed or ground very sharp. and they work 100x better.