View Full Version : Using lube to turn Aluminum?

T Long
07-19-2003, 05:15 PM
Hey Guys,

I'm getting my feet wet in the world of home machining and have a basic question.

I'm turning 6061 and 2021 aluminum round stock. I have not seen any significant difference between cutting dry or with lubricant.

I would prefer to cut dry due to the easier clean-up.

Should some type of lube be used?

Thanks in advance!

07-19-2003, 05:31 PM
If you're not having any trouble without, don't worry about it.

I find that some alloys of aluminum, however, are "gummy" and tend to weld to the tool. It seems particularly to be a problem with the softer alloys. If you run into that, I think you'll find that some kind of lubricant (kerosene is pretty good for aluminum) will help.

07-19-2003, 06:25 PM
Most of my turning is with 6061 or 7075 and I've never needed any lube, tho, your cutters may last a little longer if you use a lube. Other than that, like SGW said, if you're not havin' any trouble....(if it ain't broke, don't fix it).
BTW, I use WD40...if I need a lube. One of the local stores, Dollar General, had them for $0.99 each, so I bought a case(12). These "El Cheapo" stores are a good source of bargains like this.

07-19-2003, 07:45 PM
If you take a pass and start dry and then spray some WD40 on about half way through the cut you will probably notice that you get a better finish. Easy test with obvious results. The lube helps limit built up edge referred to as BUE in machinability literature which is aluminum sticking to the cutting tool. It sticks and then breaks off and a new BUE builds up. The repeating process makes for a torn and galled surface on a microscopic size range. Just about any lube does the job. I use WD40 or something similar. It stinks and makes smoke but not much other mess.

07-19-2003, 08:17 PM
Lube it! If you are turning, milling or using a tap you will see a lot less cutting pressure with A-9 or Alumicut. I have used W-D40 and found a world of difference in cutting pressure and finish. They smell like parifin but they work great.

T Long
07-19-2003, 10:09 PM
When using WD40, do you guys use a brush to apply a coat to the part to be turned or do you continuously apply the lubricant?

07-19-2003, 11:51 PM
Don't worry about lube...Its nice to use, but I agree that it can be messy...HEAT is your worst enemy..aluminum will start the BUE when the part gets too hot or dull...I only use coolant when doing on the CNC..but I never use it on manual turning..never had a problem...If you are turning a 5" down to 2", then you should use something to control the heat.


07-19-2003, 11:55 PM
We had a thread about this recently. I use olive oil, extra virgin. It is actually better for tapping but not so hot for turning. I have found the best lubricoolant for turning aluminum is pure ethyl alcohol. It lubes the cut, and evaporates fast leaving no mess. It is hard to obtain.

07-19-2003, 11:56 PM
double post...

[This message has been edited by Evan (edited 07-20-2003).]

07-20-2003, 10:24 AM
never used ethyl for turning aluminum, but kerosene is far more economical than most of the other fluids including wd-40. Kerosene @ under $2.00/gallon, ethyl alcohol, 190 proof, about $20.00 for about 750 ml.

07-20-2003, 10:25 AM
Evan: Isn't ethyl alchol just drinking alcohol, as in ererclear? Paint stores sell it as denatured alcohol.

07-20-2003, 11:42 AM
ethyl alcohol is grain alcohol, the stuff you CAN drink. Methyl, is also known as wood alcohol, and is NOT drinkable, it is poisonous, and is corrosive to some materials as I have been told. (OK for use as a "gas line antifreeze" in cars with carburetors, NOT fuel injection, where products made with ethyl are ok). Denatured alcohol is frequently methyl alcohol.

[This message has been edited by gvasale (edited 07-20-2003).]

07-20-2003, 12:25 PM
I agree entirely with SGW. If you aren't having trouble then don't worry about it. The heat treated alloys will give you less trouble about sticking to your tools than un-heat treated. I machine quite a lot of 6061-T6 or T651 and don't use flood coolant unless I am drilling big holes and need to remove a lot of material quickly. For that I use a water soluble oil. I have had success with Rust-Lick WS 5050 sold by MSC. For tapping or for drilling small holes I use Tap Magic for aluminum, also sold by MSC. If you have concerns about safety read the MSDS. This is not an endorsement of either product --- they just work for me.

07-20-2003, 01:46 PM
Several here mentioned WD40. I've used that a number of times. It smokes a lot if the work is hot. Starret's equivalent of spray-can lubricant doesn't smoke when hot. Of course, Starret's isn't on sale at the discount houses though.

Herb Helbig
07-20-2003, 02:25 PM
For what it's worth, I'll throw in that if you want to LUBRICATE Al sliding on Al, use sope.


Herb Helbig
07-20-2003, 02:26 PM
<font face="Verdana, Arial" size="2">Originally posted by Herb Helbig:
For what it's worth, I'll throw in that if you want to LUBRICATE Al sliding on Al, use sope.


Sope = Soap!!!


07-20-2003, 04:50 PM

Yeah, you can cut Al dry. Kerosene works too. Lots of clearance. My pipe tends to make the kerosene go WOOF!

07-20-2003, 06:29 PM
WD-40 works fine for me. Kerosene or BBQ lighter are about the same. Either ethyl or methyl alcohol are more flammable than kerosene and will present more of a fire hazard.

07-21-2003, 12:28 AM
Methyl Hydrate (gas line anti-freeze) can increase your aluminum cutting ability about ten times - it is fire hazard as well. It does wonders on high Silicon Aluminum alloys though....

Safety First!

Paul Alciatore
07-21-2003, 03:33 AM
I find that WD-40 does make a big improvement both turning and milling the common aluminum alloys I use. Much better finish and no BUE.

I usually apply it with a pump sprayer sold by the makers of the WD-40. I have two in the shop and keep them refilled from a gallon can. The sprayer can be adjusted for either a stream or a mist. A well aimed squirt every 10 to 15 seconds seems to work OK. I also have some in one of those "no spill" dispensers with an acid brush for application. I use this for turning small work. This uses less WD so there's much less mess to clean up. I also keep Tap Magic and Tap Magic Aluminum in these dispensers for easy use when drilling, tapping, and some turning.

[This message has been edited by Paul Alciatore (edited 07-21-2003).]

07-21-2003, 09:48 AM
I find the alcohol to be less of a hazard because it evaporates much more quickly. No worries about a kerosene soaked rag in the trash bin.

07-21-2003, 11:04 AM
When the alcohol evaporates, it isn't gone. It's mixed with the air in your shop where it becomes an explosive hazard instead of a fire hazard.

07-21-2003, 11:20 AM
Ethyl alcohol has a Stoichiometric mixture ratio of 9 to 1. This means that for it to present an explosion hazard in my shop which has a volume of approx 30 cubic metres I would need 3.3 cubic metres of evaporated pure alcohol. Not too likely. I can't even drink that much.