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Black_Moons
08-16-2009, 01:56 AM
Hi, if im getting some HSS endmills for general aluminum use, im assumeing any real pocketing/sloting operations should be done with 2 flute high helix endmills for highest feed rate with proper chip clearance, but what coating if any should I get for them?
Uncoated? TiN? or TiCN?
reasons?

Jim Shaper
08-16-2009, 02:47 AM
6061 has a lot of abrasiveness and also tends to weld to HSS. The coatings help keep it sharp longer, and also help prevent the chip from fusing to the teeth.

For occasional use, you could get away with bare HSS and just be sure to lube it good (wd40 works as does kerosene - nothing fancy needed). The coatings on my carbides don't hold up too long when I cut AL, so I wouldn't invest much in them unless you're doing production and are willing to pony up the money to keep changing out the cutters.

toastydeath
08-16-2009, 03:40 AM
The coatings you mentioned are for steels. At high temperatures, they become solid lubricants. Aluminum doesn't get that hot, and they don't really affect performance much.

The "best" coating for aluminum is ZrN, which behaves very similarly to diamond. Either that, or raw carbide, polished.

beanbag
08-16-2009, 05:21 AM
lube or no lube for the zrn?

Black_Moons
08-16-2009, 07:07 AM
ah. so theres no downsides to TiN/TiCN coatings when doing aluminum other then it may be a waste of a dollar or two?

beanbag
08-16-2009, 07:11 AM
Tin is not recommended for aluminum coz the Al tends to stick to it

Black_Moons
08-16-2009, 07:46 AM
Beanbag: Really? even more then bare HSS? Or only worse then bare (or polished carbide?)

I have read one other forum post to that effect but no other evidence online. (but its very hard to search the subject because 'TiN = Tin, and searching for tin + aluminum = results about cookware and stuff. Searching 'Titanium nitride' 'aluminum' + anything brings up results about 'Titanium Aluminum Nitride aka TiAlN') Can you refer me to any webpages that also cite this?

the only aluminum that seems to stick to my TiN coated endmills is the cutting oil coated microswaff that just wipes right off (but also sticks to everything includeing my spindle and collets) But then, I use cutting oil religiously with aluminum ever since I had some stick to the end of a carbide tool in my lathe and really ruin an OD.. Doesnt need much just a drop here and there but it really keeps down on the aluminum welding to my cutting edges over dry.

How about 3 flute endmills? what are they best for?

airsmith282
08-16-2009, 07:56 AM
it really dpends alot on your speed and feed waht the aluim is going to do even to an HSS cutter i own only one carbide cutter and never even used it yet other then testing it after i turnned down the shank to fit my 1/2 inch collet , other wise i use just regual HSS cutters for everything, i also dont lube alum steel yes but aluim or brass or bronze no lube, alot of it depends on if you are plunging it or slot cutting etc,, i like the idea of tin or carbide coated endmills they look cool and the coatings to help for the purpose intended, i usully run aluim at a high speed slow feed rate makes a really nice surface when cutting and prevents gaualling, when slotting i move the cutter in and out i dont just start feeding and keep going as that would start gumming up the cutter... any how hope this helps, also i take shollow cuts on aluim as well this also prevents binding and gaulling of the aluim on the cutter..

to each his or her own i always say

Dragons_fire
08-16-2009, 08:03 AM
i was told (and it may not be true), that Ti coatings are applied after the endmill has been sharpened, so it ends up with a slightly rounded cutting edge. so for soft metals, its better to us HSS cutters because they will be slightly sharper.

DaHui
08-16-2009, 11:37 AM
This will probably draw some fire but I say forget about two flute. Get some three flue (coarse) roughing end mills to use for anything related to "material removal." They just plow through material like it's their job.

For surface finish switch to...just about anything. I use 4 flute with some WD40 and the surface turns out fine...for my HSM purposes. It saves me money since I can use the same mill on both steel and aluminium and allows me to justify the extra cost of the three flue roughers.

http://www.the-alchemist.com/Images/Shoptask/bandsaw/DSC04934.jpg

lazlo
08-16-2009, 11:49 AM
The coatings you mentioned are for steels. At high temperatures, they become solid lubricants.

And you have to run the cutter at insane speeds and feeds to get the coatings to phase-change, so they're effectively useless for HSM'ers.

wierdscience
08-16-2009, 12:00 PM
If you can catch them onsale at MSC-

http://www.osgtool.com/HSS-CoENDMILL-c530.htm


OSG rules!!!!!BTW:D

JoeFin
08-16-2009, 12:37 PM
I do quite a bit of slotting work on small detailed parts with 9/64 - 2 flute end mills. Best results are with solid carbide running flood coolant. Tiny end mills have a tendency to deflect off the work piece and any chips not evacuated from the cutting surface

Once I get up to 3/8 and above, there becomes many more options

websterz
08-16-2009, 05:37 PM
Beanbag: Really? even more then bare HSS? Or only worse then bare (or polished carbide?)

I have read one other forum post to that effect but no other evidence online. (but its very hard to search the subject because 'TiN = Tin, and searching for tin + aluminum = results about cookware and stuff. Searching 'Titanium nitride' 'aluminum' + anything brings up results about 'Titanium Aluminum Nitride aka TiAlN') Can you refer me to any webpages that also cite this?

the only aluminum that seems to stick to my TiN coated endmills is the cutting oil coated microswaff that just wipes right off (but also sticks to everything includeing my spindle and collets) But then, I use cutting oil religiously with aluminum ever since I had some stick to the end of a carbide tool in my lathe and really ruin an OD.. Doesnt need much just a drop here and there but it really keeps down on the aluminum welding to my cutting edges over dry.

How about 3 flute endmills? what are they best for?

Hey Black_Moons, drop me another line with your mailing address and I will send you a few high helix 2 flute endmills that are made specifically for aluminum. I have 2 lifetimes worth of them knocking around the shop. They came from Boeing and are either brand new or freshly resharpened. They are dipped and wrapped and wicked sharp!! Just "pay it forward" as they say and do someone else a favor someday.

Jim Shaper
08-16-2009, 05:55 PM
Using two flutes is due to the softer material allowing for higher SFM and feed rates. You want those big reliefs on the teeth to funnel out the large chip volume you can generate with AL. If you push it slow enough, you can cut it just fine with 4fl or more, but the chips don't evacuate for beans and you end up with them wedged in the cutter till it's just rubbing.

snakebit95
08-16-2009, 06:36 PM
I actually use the OSG Blizzard carbide 2-flutes. They ripp through aluminum better than anything I have found. A small constant stream of air will easily move the chips from the cutting area. Avoiding recutting of chips is the key to machining aluminum and getting any kind of nice surface finish. Hope this helps!!

Highpower
08-16-2009, 07:00 PM
Using two flutes is due to the softer material allowing for higher SFM and feed rates. You want those big reliefs on the teeth to funnel out the large chip volume you can generate with AL. If you push it slow enough, you can cut it just fine with 4fl or more, but the chips don't evacuate for beans and you end up with them wedged in the cutter till it's just rubbing.
So does that mean the 4 flute roughers I bought to hog out aluminum was a bad idea? I don't like wasting money I don't have... :(

websterz
08-16-2009, 07:09 PM
So does that mean the 4 flute roughers I bought to hog out aluminum was a bad idea? I don't like wasting money I don't have... :(

I have cut a lot of AL with 4 flute roughers, both carbide and TiN coated HSS. A little WD40 always kept the chips from welding in.

toastydeath
08-17-2009, 12:05 AM
lube or no lube for the zrn?

For a HSM, run the coolant if you've got it and can stand the mess. It doesn't matter too much, though. Once you get past a certain speed (couple thousand SFM) you want to lose the coolant, because the aluminum will stay molten and just fly off the ZrN. The coolant would just solidify it on the endmill; realistically, that's not a problem for a home shop.


i was told (and it may not be true), that Ti coatings are applied after the endmill has been sharpened, so it ends up with a slightly rounded cutting edge. so for soft metals, its better to us HSS cutters because they will be slightly sharper.

True. However, dead sharp is really only "better" if you plan to take light cuts. I get very nice finishes with honed-off AND coated edges in aluminum. It's a matter of understanding what goes into surface finish; tool sharpness is only one of a manifold of considerations, albeit a very substantial one.

ANY coating will "dull" the edge; this is why many shops are using polished carbide tooling. Nothing wrong with using coatings; you just have to keep in mind the things it does. You won't tend to get as good a finish with anything less than a .010-.015" pass with some tools.

For the HSMer, uncoated is probably the way to go for most things.


This will probably draw some fire but I say forget about two flute. Get some three flue (coarse) roughing end mills to use for anything related to "material removal." They just plow through material like it's their job.

For surface finish switch to...just about anything. I use 4 flute with some WD40 and the surface turns out fine...for my HSM purposes. It saves me money since I can use the same mill on both steel and aluminium and allows me to justify the extra cost of the three flue roughers.

To me, aluminum means three flute and nothing else. There's no real great reason to use two flute in Al for slotting unless you have bad chip evacuation issues; three works just as well and has as good chip clearance, but doesn't evacuate them quite as well. And in pocketing and anything else, three tends to be the right number for roughing and finishing. You can really tear up with a bigger 3 flute endmill with ~.015" per tooth feeds to rough something out, or you can spin it a bajillion RPM and finish at .001" IPT.

This is all just what works for me, though.

beanbag
08-17-2009, 06:49 AM
Today I tried a TiCN 3 flute high helix end mill and did some light passes in Aluminum. With and without coolant. It cut well and left a really nice surface finish. I think it mostly has to do with the high helix and extra flute, namely that there is always a cutting edge on the aluminum so the tool pressure is more even. With a low helix 2 flute, there might be times when the end mill isn't touching the material at all.

I did not know that Aluminum can be abrasive, with might explain why I seemed to get some wear when dry slotting with a 3 flute the other day. I think the coolant helps protect the end mill, though, especially when chip clearance in a problem. Just my observations...

BobWarfield
08-17-2009, 11:20 AM
Three flutes are a winner, especially if your mill doesn't have very high spindle speed available. They don't seem any more prone to chip clogging than a 2 flute. I get mine from MariTool. High helix end mills help with chip evac too.

4 flutes and higher can also be used on aluminum, but I would caution in a couple of ways. First, I prefer not to use them at all for slotting where the cutter is totally buried. You're just asking for chip welding. With that said, you can feed them twice as fast as a 2 flute at a given spindle speed, so I like to use them when the cutter isn't completely buried. For example, when edge milling. I also think they give me a little better finish as they effectively multiply the spindle speed versus a two flute.

I am convinced a rougher like the one pictured can evac chips better as can the larger endmills. Still, it's annoying and just a bit scary to weld a 1/2" endmill to the job and snap it off because your CNC is whizzing along in the cut to fast and without good chip evac.

Second, the coolant seems to matter most as lubricant. We HSM's usually don't run fast enough to need "cooling". So choose one that can lubricate and keep those chips from gluing to the cutter. WD-40 is good as is kerosene (lots of that in WD40). Get it in a liquid with a spray bottle, not the aerosol, it's a lot cheaper.

Third, chip evacuation is king. If you can't run flood, get a mister. If you can't mist, run an air stream continuously. If you can't do that, you'd better baby sit.

Fourth, change your feedrate when the endmill is buried. I use a factor of 2/3 of the recommended with a buried cutter so it is feeding slower. That seems to help tremendously. Going around a corner is even touchier in a slot.

Most of the broken endmills I've had were for lack of chip evacuation because I got tired of baby sitting an aluminum job and the cutter was buried. It's amazing how fast those chips build up down in that hole.

You'd be surprised at the feedrates your little HSM mill can do if you get everything set up properly. I have converted my mill to CNC, so I can take advantage of that. Not sure I would care as much on a manual mill, but I do get impatient.

Cheers,

BW

lazlo
08-17-2009, 11:43 AM
i was told (and it may not be true), that Ti coatings are applied after the endmill has been sharpened, so it ends up with a slightly rounded cutting edge. so for soft metals, its better to us HSS cutters because they will be slightly sharper.

That's definitely true, and it applies to inserts as well: the PVD/CVD coatings are applied as a last step, and the coating rounds-over the edges, effectively dulling the edge.

But a razor sharp edge, especially on carbide, is exceptionally fragile, so rounding over the edge usually improves the tool life a lot...