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Author Topic: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?  (Read 28791 times)

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #30 on: January 19, 2010, 09:43:49 AM »
Here Ya go Ray, the way it's done.....

Now that's impressive!  How did you manage to NOT break it?

Regards,
Ray L.

Quick on the big red button! We only lost coolant for a few seconds when this happened - 6061 - T6.

You would think that those tendrils of aluminum extruding off the end mill would be delicate - they're harder than the piece that was being cut.

Offline simpson36

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #31 on: January 19, 2010, 11:00:59 AM »
That thing looks obscene    :P

Offline Chaoticone

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #32 on: January 19, 2010, 06:05:59 PM »
Only experience can give you results like that. Your good Bill.  ;D

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #33 on: January 19, 2010, 11:23:41 PM »
Hi all i got a nice speed and feed calculator from cnc cookbook .com its in beta testing ive been using it for a while works real well and it also has a lot of other useful gadgets on it and its free.I run production runs in 6061 exclusively and this calculator has worked fine for chip load calc. and feed rates might be worth a try gives you a great starting point and seems to do very well with end mills .I use accupro end mills and i usually use three flute end mills carbide coated on 6061 it gives a better finish smaller chips and no welding i use flood rustlic coolant works great in aluminum .
Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #34 on: January 19, 2010, 11:44:52 PM »
Hi all i got a nice speed and feed calculator from cnc cookbook .com its in beta testing ive been using it for a while works real well and it also has a lot of other useful gadgets on it and its free.I run production runs in 6061 exclusively and this calculator has worked fine for chip load calc. and feed rates might be worth a try gives you a great starting point and seems to do very well with end mills .I use accupro end mills and i usually use three flute end mills carbide coated on 6061 it gives a better finish smaller chips and no welding i use flood rustlic coolant works great in aluminum .

Yeah, I'm using G-Wizard to validate my own numbers.  It's a VERY nice tool.  I'm now cutting the "gooey" T651 at 100IPM, *without* coolant, and getting a pretty nice finish!

Regards,
Ray L.
Regards,
Ray L.

Offline Dan13

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #35 on: January 20, 2010, 03:17:10 PM »
I don't know what you mean when you say "coated carbide", but I've learned that the usual coatings like TiCN, while good for extended tool life, interfere with the flute sharpness. Any coated tool I've seen had a less sharp edge than that of an uncoated tool. For aluminum you certainly want the flut to be as sharp and smooth as possible to reduce the friction and heat. Thus not coated mills are better for aluminum.

Here is a good article http://www.moldmakingtechnology.com/articles/030401.html , see second paragraph from the bottom.

May be you mean other coatings, designed specially for aluminum? That make the surface smooth?

Daniel
Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #36 on: January 20, 2010, 04:25:24 PM »
I don't know what you mean when you say "coated carbide", but I've learned that the usual coatings like TiCN, while good for extended tool life, interfere with the flute sharpness. Any coated tool I've seen had a less sharp edge than that of an uncoated tool. For aluminum you certainly want the flut to be as sharp and smooth as possible to reduce the friction and heat. Thus not coated mills are better for aluminum.

Here is a good article http://www.moldmakingtechnology.com/articles/030401.html , see second paragraph from the bottom.

May be you mean other coatings, designed specially for aluminum? That make the surface smooth?

Daniel

That depends on whether you're looking for ultimate surface finish, albeit with limited tool life and/or machining rates, or good surface finish with longer tool life, and/or faster machining rates.  Coated tools can last much longer than uncoated tools, and often enable MUCH higher feedrates.  In a production envinronment, time is money, and tools are money, so surface finish will often take a back seat to tool life and throughput.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #37 on: January 20, 2010, 04:51:46 PM »
I'm not sure I buy the sharpness argument, as these coatings are literally a few molecules thick.

That said, I agree that sharpness and surface smoothness is key to successful soft aluminum cutting, as I commented previously. The primary reason I like the coated cutters is not for higher speed or production longevity, since I can't cut at what would be considered 'high speed' by today's standards and I do prototypes and not production as a rule.

For those of us who don't have or want a flood system, certain coatings offer a measure of 'anti pick-up' to the tool. So aluminum behaves more like an egg in a 'teflon' coated pan rather than a steak on the grill, often allowing dry machining with only compressed air for cooling and chip evac.  Uncoated cutters always need lube of one kind or other, in my experience. For those with flood cooling, the debate is somewhat academic. Many moons ago I had a bridgeport with flood cooling and you really didn't even have conversations about material 'welding' itself to the cutters . . .  on the other hand, I wan't cutting any soft aluminum back then.

The caveat with uncoated cutters on aluminum is that you *might* get away with a dry cut  . . . . and you might not. The trouble is the way you find out that you didn't . . . which can get expensive in a hurry. I may as well add once again that in my view, mist 'coolants' like Kool Mist that I have tried are no better than dry cutting for soft grades of aluminum, however, something that I find very effective for band saw blades is 'grinder's paste'. This stuff is pretty miraculous at keeping aluminum from sticking to saw blades and grinding belts . . . . . just don't use it for final finishing if you plan to paint the part afterward.

Offline Dan13

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #38 on: January 21, 2010, 01:16:52 AM »
I'm not sure I buy the sharpness argument, as these coatings are literally a few molecules thick.

May be, but one thing I know is that when you come to metal plating you usually want to avoid sharp corners because the coating doesn't hold on a sharp corner... sure true for anodizing, not sure about other coatings.... ??? could be something to do with this...

But please do compare a coated and uncoated edge for sharpness. I think there is a noticeable difference.

That said, I agree that sharpness and surface smoothness is key to successful soft aluminum cutting, as I commented previously. The primary reason I like the coated cutters is not for higher speed or production longevity, since I can't cut at what would be considered 'high speed' by today's standards and I do prototypes and not production as a rule.

So what is the primary reason you like coated cutters for aluminum?

The caveat with uncoated cutters on aluminum is that you *might* get away with a dry cut  . . . . and you might not. The trouble is the way you find out that you didn't . . . which can get expensive in a hurry.

That's true ;)

something that I find very effective for band saw blades is 'grinder's paste'. This stuff is pretty miraculous at keeping aluminum from sticking to saw blades and grinding belts . . . . . just don't use it for final finishing if you plan to paint the part afterward.

My almuminum supplier always use this pasty thing on their band saws... so you say it's a grinder's paste...

Daniel
« Last Edit: January 21, 2010, 01:19:14 AM by Dan13 »

Offline simpson36

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Re: Anyone Here Have Experience Milling 6061-T651 Wrought Plate?
« Reply #39 on: January 21, 2010, 07:18:16 AM »
I don't want to get into a science discussion on a hobby forum, but if you are curious about the coatings, you need to look into how cutting works on a microscopic level. The reason a lot of inserts are not sharp is because they don't need to be. The material actually 'tears' off and the very tip does not even contact the material.

The problems occur just aft of the tip where the metal chip is scraping past the tool surface after it is torn from the parent material. If you run inserts as fast as they are designed to run, the wear point is a crater behind the tip. This erosion failure of the cutter surface and is why coatings to improve abrasion resistance are effective.

Look at the part of your end mills where the chip is curled around after the actual cut. The sliding motion here creates intense heat which is the devil in aluminum and other gummy low melting point materials. In this case, abrasion is not so much the problem as heat and 'pick-up' and a coating that reduces friction or imparts a 'lubricity' in these surfaces of the cutting tool are effective in sort of a similar way to flood cooling.

That's as far into it as I want to get, but it is a fascinating subject with lots of technical information available for those with an interest.

As to grinding paste, there are no doubt lots of different ones. I was doing some consulting recently that netted me a sample of Boeing's 'Bio-Lube' product in paste form.  It works well enough that I bought their gel version (have not tried it yet). Normally I use Eastwood's stuff. They call theirs 'grease' for some reason, but both these are more accurately described as 'sticks', methinks.
http://www.eastwood.com/ew-grinders-grease-8-oz.html