# Issues Milling Aluminium



## Twizseven (Feb 3, 2013)

Hi there,

I've been member of this site for 3 or 4 months and just look with amazement at some of the work being done by members. I am based near Lichfield in the UK.   I have workshop with several lathes (Colchester Student and Myford 7) and and milling machine (Chester Super Lux) but cannot find the time to use them as I would like.  I have been trying today to mill a 1/4" wide slot 2.5" long in a 1/4inch thick aluminium sheet.  I am using a 1/4" dia. 4 flute slot cutter.  It pierces down through the aluminium OK and cuts the first 1/2" of the slot and then the ali just builds up on the cutter and it ceases to cut.  I am not geared up to use cutting fluid.  I have had problems every time I have tried to mill aluminium.  What am I doing wrong. 


Thanks in advance,

Colin


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## Tin Falcon (Feb 3, 2013)

use pubished speed and feed
a two flute mill cutter will give more chip clearance. 
a bit of w-d 40 or paraffin (kerosene in the USA)will keep the chips from sticking.
What depth of cut are you using you may be cutting too deep at ones as well. 

Tin


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## Swifty (Feb 3, 2013)

Hi Colin,
Welcome to the site. You could try using some WD40, CRC etc whilst cutting. I always have a can available when cutting aluminium. Depending on the grade of aluminium, some cuts really well whilst some cuts like putty.

Paul.


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## stevehuckss396 (Feb 3, 2013)

Twizseven said:


> Hi there,
> 
> I have had problems every time I have tried to mill aluminium.  What am I doing wrong.




Lube!

It's that simple. The aluminum gums up and welds to the cutter and it will stop cutting. You don't need to flood the cutter, just a squirt here and there of what ever you perfer. I use WD40 myself but know others who use kerosene, transmission fluid, cooltool, you name it. Just lube with something and you should have better results.


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## goldstar31 (Feb 3, 2013)

One of the best lubricants for aluminium is lard oil. I would try lard, bacon grease or cooking oil as alternatives. I use lard oil almost exclusively having a Myford as well. I drill and tap with it too.

Cheers

Norman


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## Twizseven (Feb 3, 2013)

Thanks Tin for quick response.

Not sure I have a two flute cutter but will have a look.  I tried 25 thou depth of cut and also full depth of cut.  I started off with a 6mm hole drilled all way thru.  Now I think of it I have used paraffin when drilling ali on lathe but never gave it a thought with the milling..

Colin


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## Twizseven (Feb 3, 2013)

Okay, So it looks as though lubrication is the key.  I'd better find out the old Fairy Liquid plastic squeeezy bottle.  I think this ali is very soft.  Now I have gummed up milling cutters whats the best way to remove the ali from the flutes.

Colin

PS thnaks for the other very quick responses.


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## stevehuckss396 (Feb 3, 2013)

Twizseven said:


> Okay, So it looks as though lubrication is the key.  I'd better find out the old Fairy Liquid plastic squeeezy bottle.  I think this ali is very soft.  Now I have gummed up milling cutters whats the best way to remove the ali from the flutes.
> 
> Colin
> 
> PS thnaks for the other very quick responses.




Lube and start milling and i would be willing to bet the cutter will clear itself.


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## Omnimill (Feb 3, 2013)

Once you're clear on speed and feed WD40 or paraffin works fine for Aluminium Alloy, also stop and clear the chips once in a while. Bottom line though is the type of alloy. I tried to mill some unknown stuff a while back and it was just too gummy to machine well.


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## canadianhorsepower (Feb 3, 2013)

Twizseven said:


> Okay, So it looks as though lubrication is the key. I'd better find out the old Fairy Liquid plastic squeeezy bottle. I think this ali is very soft. Now I have gummed up milling cutters whats the best way to remove the ali from the flutes.
> 
> Colin
> 
> PS thnaks for the other very quick responses.


 
If it doesnt remove itself (aluminium from the mill)
let your end mill sit in sulfuric acid (drain cleaner) and the aluminium
will vanish........ 
use a well ventilated area and cover your hand properly.
if you have any silver where bring them at your neibour's house when doing thisRof}


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## Lakc (Feb 3, 2013)

Do not use any fancy titanium coated tools to cut aluminum either. Ti= aluminum glue.


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## terrywerm (Feb 3, 2013)

Lakc said:


> Do not use any fancy titanium coated tools to cut aluminum either. Ti= aluminum glue.


 
I forgot about that once and used a TiN coated end mill on some ali -  but not for long!!   :wall:   Luckily it did not stick so bad or so long that it ruined the part, and I was able to switch over to a regular HSS end mill and finish the job. 

I guess I won't make that mistake again!  ;D


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## canadianhorsepower (Feb 3, 2013)

terrywerm said:


> I forgot about that once and used a TiN coated end mill on some ali - but not for long!! :wall: Luckily it did not stick so bad or so long that it ruined the part, and I was able to switch over to a regular HSS end mill and finish the job.
> 
> I guess I won't make that mistake again! ;D


 
the reason for this is simple 
you have to reduce your speed by 30% for this not to happen
even in steel


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## Tin Falcon (Feb 3, 2013)

lard oil  IS recommended for milling 
so is mineral oil and soluble oil  even some lard oil mixed with kero probably OK. NOT Bacon grease yuk to much corrosive chemicals nitrates salts etc no way Jose' 
Tin


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## Omnimill (Feb 3, 2013)

Tin Falcon said:


> NOT Bacon grease yuk to much corrosive chemicals nitrates salts etc no way Jose'
> Tin



Now that's a shame Tin as it would smell soo nice while you were working!


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## Twizseven (Feb 3, 2013)

I'm sure I have bottle of sulphuric acid around from battery top ups so will try that to clean up cutter

Thanks for all the advice.
Colin


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## abby (Feb 3, 2013)

You clean your drains with sulphuric acid ?


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## canadianhorsepower (Feb 4, 2013)

Twizseven said:


> I'm sure I have bottle of sulphuric acid around from battery top ups so will try that to clean up cutter
> 
> Thanks for all the advice.
> Colin


 
sorry :wall::wall:not sulphutic acid

but muriatic acid ( cement cleaner)


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## LongRat (Feb 4, 2013)

When my cutters clog I knock the clogging out with a short length of 1.6mm piano wire and a hammer.  Not chipped a tool yet.
Also, if you can get GT85 (Halfords) use some of that, it is even better than WD40 as a lube for aluminium.  However I think switching to 2-flute will make the biggest difference, its possible to clog a 4-flute endmill that small in aluminium even with flood coolant in some of the softer grades.


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## Twizseven (Feb 4, 2013)

Luc: I must admit I wondered what there was in drains that needed sulphuric acid.  I will get cement cleaner and put the suphuric away.  

LongRat:  I assume GT85 is Halfords equiv of WD40.


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## jack620 (Feb 4, 2013)

Sulfuric acid is commonly used in drain cleaners. Whether it is any good at cleaning milling cutters I have no idea.

http://www.walmart.com/ip/Liquid-Lightning-Buffered-Sulfuric-Acid-Drain-Cleaner/17133944


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## canadianhorsepower (Feb 4, 2013)

jack620 said:


> Sulfuric acid is commonly used in drain cleaners. Whether it is any good at cleaning milling cutters I have no idea.
> 
> http://www.walmart.com/ip/Liquid-Lightning-Buffered-Sulfuric-Acid-Drain-Cleaner/17133944


 

Quote:
Originally Posted by *Twizseven* 

 
_I'm sure I have bottle of sulphuric acid around from battery top ups so will try that to clean up cutter

Thanks for all the advice.
Colin_

sorry 
	

	
	
		
		

		
			








not sulphutic acid

but muriatic acid ( cement cleaner) 
__________________
*Luc*

*"if you dont stand for something*
*you will fall for everything"*


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## blighty (Feb 4, 2013)

i think Halfords sell WD40 by the gallon, its a lot cheaper than buying it in a can. if you go the gallon of WD40 way, put it in one of them spray bottles you get from B&Q for spraying your house plants with. you wont go through as much WD40 using a spray bottle.

or, as others have said Ali loves paraffin. B&Q/Home Base 4lt about 6 quid. 

or..... soluble oil, if you cant find it locally, ebay's the place. i just had a quick look  1lt of soluble around £10. 5lt £26 and so on. it will tell you on the bottle what ratio (oil to water) to mix it up with. the stuff i get is 10-15 to 1 for e.g. again mix a load up in a bucket and use it to re-fill your spray bottle up when it runs out.


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## MachineTom (Feb 4, 2013)

As already been stated lube is needed, 2 fluted cutter, and I am guessing you are running slow, with a two flute 1/4" you can use 2000 rpm and more. There are end mills just for AL, the difference is they are very sharp as compared to not very sharp on a standard HSS cutter, don't bother with carbide, you don't need it.

To avoid gumming up a bit with AL, run fast, do not recut chips, meaning blow out the channel you are cutting, do not run back through the chips, do not dwell in one spot, keep feeding, use some lube.  

To clean a gummed up cuter just run it through some steel, gently but with feeling.


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## abby (Feb 5, 2013)

Aluminium dissolves readily in caustic soda  which  , unlike sulphuric acid  , will not attack steel .
Most drain cleaners are designed to dissolve fats and grease , the usual cause of blockage , and use alkali compounds rather than acid.
In the UK it is an offence to put high acid concentrations into public sewers.


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## Chriske (Feb 5, 2013)

Hi,

For all cutting action, lathe, milling, drilling I use (own formula) a mixture 50% standard oil - 50% White spirit (Belgium , don't know the English name for White spirit..(help..!)  Works *very* well...!
Used with aluminum it gives me, every time again, a high glossy surface.

For reaming and cutting threads I use special cutting fluid.

Chris


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## LongRat (Feb 5, 2013)

GT-85 is not only available from Halfords and isn't their product, it is just an easy way of getting it.  I buy it in 1 litre trigger spray bottles on Ebay.
It is definitely not the same as WD40.  For small jobs like this I find it the easiest and most mess-free solution.  For longer runs I use soluble oil as Blighty has suggested in an air line (99.9% air, tiny bit of coolant).  Lots of people on the forum have made home made misters like I have, but for a 1 minute quick cut it isn't worth firing it up so I just use the GT-85.


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## gus (Feb 6, 2013)

Swifty said:


> Hi Colin,
> Welcome to the site. You could try using some WD40, CRC etc whilst cutting. I always have a can available when cutting aluminium. Depending on the grade of aluminium, some cuts really well whilst some cuts like putty.
> 
> Paul.



Hi Paul,

Thanks for info. Currently I am milling extruded aluminium bars which cuts very well. Some dobs of Tapmatic Tapping Oil for Aluminium gives good cutting finish. You are right.There are many grades. The annealed sheets would be hard to mill.


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