cutting aluminium 2

[alansimpson]

I am not a machinist but in my work as a mechanical engineer I have to do some building which involves milling and turning and cutting.
Of all the materials I work with aluminium alloy sheets and plates ( eg AlMgSi 0.5 F22/6060 or HE30) gives most problems with poor finish and clogging of cutters, drills, hacksaw blades.
I am mainly using HSS toos without coolant.

Could someone give advice on speeds or cutter types for general purpose aluminium.

Thanks

 

[MikeHalloran]

Use a little coolant on the hacksaw.

For everything else, just turn the speed _way_ up.

E.g. when drilling aluminum, if you've got the speed and feed high enough, the drill will literally spit small, gray, almost granular, chips out of the flutes, even on a deep hole.


Reduce the speed by half, same conditions, and you get birds nests of stringy chips, and you break drills in deep holes.



Mike Halloran
Pembroke Pines, FL, USA

 

[ornerynorsk]

Use a little cutting oil or tap magic on all operations. Super high speeds are not necessary, and will actually induce chatter on many operations. With high speed steel tooling 200 feet per minute (calculate circumference to get rpm's) is sufficient. All the books will tell you double. Production and prototype are 2 different animals, and you don't need the insane speeds and feeds of trying to save a couple pennies per part. Good luck.

 

[SincoTC]

I find a quick squirt of WD-40 works well with all aluminium alloys for the odd milling and turning job where the proper soluble oils are not available in small quantities and won't cause rust if it gets under a machine vice. If you get files clogging up (pinning), rub some ordinary blackboard chalk on the teeth.

 

[williedawg]

Always use cutting fluid of some type on aluminum if at all possible. Check out some of the water-soluble types available. Good source is MSC Supply.
As re TapMagic, make sure the one you get is compatible with aluminum.....read the label.
Agree with not going to the extremes on speeds/feeds. SFM figures are for ideal conditions.
Get a chart and start at the low end. I made one up using Excel many years ago for shop use.

 

[AdieR]

coolants - if you have it available, try paraffin / kerosene, otherwise use ordinary soluble oil coolant.

Speeds / feeds - I've found that super high speeds on aluminium tends to distort the metal and lead to poor finish, thus I'd take the speed/feed up by a given level. I tend to benchmark the speeds/feeds for steel in my head, then if I work with other materials, I'll speed it up / slow it down from that.
Hope that helps

 

[moog2]

parafin (or kerosene) is the best cutting lube for ally, just brush a bit on

 

[larrylcoyle]

Actually guys, the speeds and feeds are mostly determined by the type of machine being used. If you have a machining center that has a relatively low hp spindle motor, you need the higher speeds and feeds. Example would be a spindle motor of 7.5hp vs one with a 15hp.

Larry

Larry Coyle
Managing Partner
Cylinder Head Engineering, LLC
CNC Porting
De Soto, KS 66018

 

[Facewithasmile]

The main problem is that the Aluminum is welding itself to the tool cutting edge. With some Aluminum Alloys it is a constant problem. Every few minutes take a razor blade and scrape the Aluminum from your cutting tool. You will find that you can work faster and hold closer tolerances.

 

[mfgenggear]

The type of tools & machine will make the difference.

bridgeport vs. Morie Seiki (Rigidity?)
single spindle vs ?
2 flute vs. multiflute
Milling cutter vs fly cutter

Must use some type of oil or coolant to flush out chips & keep tool cool.

Roughing cycle~ slower SFPM but deeper depth of cut & increased feed.

Finishing Cycle~ Higher SFPM but smaller depth of cut & finer feed.(Take light cuts at high speed) better finish.

Use the recommended feeds and speeds from the Internet.

 

[powerhound]

A big factor in aluminum clogging up cutters is the number of flutes. Make sure you're using a 2 or 3 flute cutter.

Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[powerhound]

Alan,
Why aren't you using coolant?

Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[jhartsock3]

The I would agree with most about the feed and speeds. And that on aluminum you must use coolant. I have had the best luck with water souluable coolants. But I would suggest that you talk to your local tool rep. and make sure that you are using tooling designed for aluminum. A lot of times it can be a simple change of adding a wiper to a face mill for better finish. Or using a diffrent type of chip breaker. Also cobalt is a little high end for almuinum I would stick to HSS tooling or carbide if drilling a tight location.

 

[ProgressiveRacing]

Use coolant, even if you have to spray it on the tool with a bottle.

Use as much RPM as you have... can't have too much RPM for finishing on aluminum. If you're finish profile-milling, use 3-flute cutters... should be obvious why. Regardless the cutter, always climb cut for best finish. If you're doing this on conventional machines, leave as little stock as necessary (.005-.010) and make sure you lightly pre-load your gibb-locks to prevent the machine from running away into the cut.
For roughing, back the speed down to an RPM where torque is highest, use 2-flute cutters. The rules change a bit depending on the machine, cutting strategy and volume of coolant you can get to the tool.

Use cutters specifically designed for machining aluminum alloys. HSS is fine for one-offs and projects but I'd use carbide for any kind of production milling/turning. TiN coated HSS will also help in preventing galling at the cutting edge... all that more important if coolant is sparse... ie, spray mist.

 

[saberblue]

The addition of a metal removal fluid or coolant will make what ever you do with tooling,feeds and speeds, etc. better.

One of the key characteristics of aluminum (Al)particularly the low silicon (Si)content alloys is the tendency of the material to weld to the tool - so called built up edge or BUE - the addition of an EP (extreme pressure)lubricant at the point of cut will help a great deal - a chlorinated EP is the most effective EP package available for AL.

Assuming that your machine does not have flood coolant I would look at applying a good chlorinated soluble oil (start at about 7%)with a good quality spray mist unit - I suggest that you look at using the coolant concentrate (as it comes from the drum) to provide high levels of both hydrodynamic an EP lubricity of operations like drilling, tapping and reaming - this will work better over all that using a special taping compound as the parts can be washed off with water and the resulting mixture used in the spray miser.

A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

 

[silveringchap]

Truth is, years ago they used parrafin as a lubricant to prevent the chip welding to the tool.This is because parrafin dosnt globulise like water it actually spreads out over the tool face better and gets under the chip.However,in the uk parrafin is a no go at work and stinks so for one off type jobs, as mentioned previously, tapping fluid is best.Modern coolant work quite well too.Modern aluminium is alloyed for machinability and so can be cut with using coolant.Dont machine dry!