Routing Aluminium sheet

[kong]

I have just finnished my machine, and want to do some test cuts in 1mm Aluminium sheet. So far, I have successfully managed to melt the ali onto the 1/8" end mill I am using.
What would therefore be some ballpark feed speeds and cutting depths, bearing in mind a minimum router spindle speed of 15000 rpm. Also, am I right to use a milling cutter, or should I plump for a more professional spiral router cutter (similar thing I guess?). Lastly, what would be a decent lubricant to use, if any? Thanks for putting up with my ignorance!

[balsaman]

Aluminum comes in all varieties. Some is very "sticky" while others machine nicely.

I have cut aluminum on my machine at 3" up to about 6" a minute .200 deep at a time. I run my router wide upen, and lighter cuts is better and easier on my machine(but I am impatient). I have had no trouble with the bit plugging up (1/4" carbide 2 flute endmill). I have been cutting 6061-T6 aluminum, which I beleive is known for it's good machining qualities. I have not used any lube.

What sort of machine do you have? If it's a wooden home made machine maybe a litle wd40 sprayed on the aluminum sheet before you begin? (since you can't flood the bit)

I know some aluminum is just too soft. You could try drilling a piece on a drill press. The soft stuff doesn't drill but just pushes the aluminum out the bottom and leaves it there, almost like you used a punch.

Eric

[kong]

Cheers Balsaman, yep, wooden machine so I'll give the WD40 a go. Maybe it's the cutter, it's a 4 flute so I guess it will always plug up quickly. As for the Ali, it has numbers on it, but they are way blurry! It's 60xx, and it's quite a hard alloy. It's been around the shed for a while, i cut it with a hand router a year ago using a 4mm aluminium spiral cutter in one pass with no problems. I guess I just gotta get used to the CNC methods! The feedrate is giving me difficulty at the mo, using Ace converter, it does not add the figures, so manual editing is necessary, then, using Turbocnc as a controller, the "feedrate override" does not seem to have any effect. I just want to get it right first time, going slow is ok, and then I can work it up from there. 0.2" = 5mm, so I should be ok cutting in one pass.

[cbcnc]

Hi Kong,

Try a 2 flute cutter if you aren't already. The problem is that the chips can't get out of the way of the cutter as it comes around on it's next pass. Therefore it packs up on the bit. You should be able to pick at it and get it out of the bit.
Also if you can, it would help to slow your router speed down some. Again that is because the chips can't eject fast enough.
They make grease sticks for cutting Al but short of that simple spray vegetable oil works too.

Good Luck,
Chris

[wms]

Kong,
Here's some numbers:
1/8" end mill at 15000 rpm is a surface speed of 490
4 fl mill at chip load of .004 would be 240" a minute
60" per minute would be a chip load of .001

[balsaman]

There is a place in ace converter to put the feed rate... Just stick in the "Prepriority code" window (F3 or whatever). You get that by doubleclicking the priority number on the right.

Eric

[HuFlungDung]

Get ahold of one of those air/oil mist units. It doesn't take much lube to do the job, plus it moves the stray chips out of the cutting zone so they don't get recut, or worse, welded back onto the surface!

[CAMmando]

If lubrication and chip evacuation doesnt fix it, you may need to cool the cut down. Since liquid coolant isnt an option, you could try pushing the feed rate (if you have it) to get the heat into the chip as much as possible. If all else fails do you have a vortek cold gun anywhere you could get your hands on ?

Do you know what grade of aluminum it is ?

[Zephrant]

On the mill, I've used a manual squirt bottle with kerosene. Cheap, and flammable...

(Just got done watching Red-Green... he should do a home shop segment.)

Zeph

[kong]

I am still waiting to get some two flute cutters, but in the mean time I have had to cut the feedrate right down to 4IPM, and I am cutting in two passes. So far, so good. Thanks for the tips guys, hopefully with the two flute cutters and dust extraction setup, all should be ok. The biggest problem has been that my router is in an enclosure to cut down the noise, so opening/closing to add lube is a pain. If the two fluters don't improve the problem, then obviously some sort of mist unit that Hu was on about may be necessary.

[HuFlungDung]

Trico MD1200 Micro-Drop dispenser is what I use.

What you save in lube, you spend on the dispenser, I guess

These units are hideously expensive ($740.00 Cdn in Travers Tool catalog) for all that they consist of, but I can vouch for the technology of their valve and nozzle design. It really is a very sensitive adjustment at the low rate of oil that it uses, but it seems quite accurate. There is no fog from this unit, and they use a vegetable based oil for health safety, although no oil fog is ever healthy to inhale.

This unit is also available on special request with a solenoid valve which you can hook up to a spare M function on your cnc.

[Don C]

the faster the trave the cooler the bit. also the less flutes the cooler the bit. slow down your spindle. use moble one water soluble coolant ( cheap $5.00 a gal and makes around 50 gal.).