Thread: WD40 and Aluminum??

Here is the senario, you friend JohnnyB is in the shop playing with his BP mill and a couple of new end mills. I'm still learning the most basic of things when it comes to operating these machines. Last week I was using some 3/8 HSS 4 flute center cutting end mills to play with some blocks of 6061. They worked ok, but seemed to make more noise than I would have thought and some the cuts were rougher than I thought they should be, specially when slotting.

Anyway, on numerous peoples advice I got some mills made for cutting aluminum. a couple of 5/8 HSS 2 flute, high helix, one center cutting, one center cuttng ball end. Once again I'm playing around with some 6061, I've got the pulleys set to 2700 rpm. Wow, these things work way better than the 4 flutes did (which were 3/8). The standard center cutting one works great, no complaints. So now I start playing with the ball end, I'm cutting a trough in this chunk of 6061, about .200 at a swipe. I notice the finish isn't great, and always on one side of the cut I'm getting a build up of chips kind of stuck to the work piece, plus a little more noise than I'd like. So...being the home owner type that I am, I try a little WD40 on the work piece. Immediately the cutter quiets down, cuts smooth, makes larger chips rather than medium "shreds". All it took was just a small spray, and it was good for three or four passes too.

My question is, I usually like to do most of my machining dry unless I can tell that it's absolutely necessary to use some kind of lube. All my previous experience has been with a lathe, most of the time I can just kinda tell when lube is in order. What can I expect in the way of lube requirements working with light cuts on aluminum and mild steel? Any single lube that would suffice in most cases?

And...what is your opinion of the situation I just described with the WD40, is this normal? Was I screwing up something else that the lube was masking? Bear in mind, I just kind of learning this stuff as I go.
Thanks
JohnnyB

Hi Johny;

I recalculated, your cutting speed is OK.
1600 rpm would be about right for 1". Sorry about the confusion.

I a firm believer in cutting fluids and oils. I have co-workers than never use them unless they are tapping. They even run to the boss when I use cutting fluids that stink. Sissies anyway.

Cutting oils are critical when machining aluminum. I stalled out the Bridgeport twice today milling aluminum without oil. Aluminum comes in all grades of gummyness. The flutes load up (weld Up)with chips. When the rake angle is full of chips, guess what....no more cutting. Aluminum tends to weld to cutting edges. Anything in the way of lubrications hinders this welding of material. I have also found that mineral oil (Petroleum oil) is best. I always keep pipe threading oil around for machining, especialy tapping, aluminum. Used motor oil would probably work but would be way to messy. The sythetic cutting fluids don't compare to mineral oil when it comes to machining alumninum.

Your WD40 probably had enough lubrication in it to make a difference. If you wish to experiment try different lubricants while drilling 1/4" holes in aluminum. When the chips fall from the drill futes when withdrawing from the hole, indicates a good lubricant for cutting aluminum.
Jim

[This message has been edited by JimGlass (edited 02-13-2003).]

[This message has been edited by JimGlass (edited 02-13-2003).]

[This message has been edited by JimGlass (edited 02-14-2003).]

Jim,
Ok, so some kind of lubricant is definately in order. That's something I'm going to be glad I know. My chart shows 600 to 1000 fpm for aluminum, and something is screwy here, it says that 400 fpm with a 1/2" mill would be 3056 rpm!
Thanks much for the info, can't wait to try it with some real oil.
JohnnyB

WD 40 and Aluminum are made for each other. In fact that's about all WD 40 is good for is a general purpose cutting oil and a low volatility cleaning agent. it's worth zip as a preservative and an lubricant.

As for spped to run 1/2 HHS end mills in aluminum a fridne of mine runs 'em up to 10,000 RPM in his VMC amidst a guyser of coolant. That's for roughing. Thin delicate parts subject to distorion and deflection from cutting forces need to be machined more sedately..

Forrest is right. WD-40 is ONLY good for aluminum cutting fluid. It will give you a mirror finish when using the correct endmill. I can & do run my endmills as fast as I can ie... as fast as my spindles will go. And you are right 400sfm on a 1/2 is 3056 rpm....

Cheap mans WD 40:-
75% kerosine or Paraffin to us UK folk and 25% Automatic Transmission Fluid.
Shaken not stirred and you won't know the difference.

John S.

I gotta agree with Forest, I didnt think that WD-40 had any use. I use Aluminum Tap Magic for cuttting and tapping fluid on Aluminum, I never tried WD. I also believe in lubricant for machining and tapping most anything that is even the least bit gummy. If not oil then a spray mist with a water based synthetic lube. The reason I dont use oil based stuff like Trimsol is because it makes me real sick if I breathe much of it.
Fred T

Ran into the WD40/Aluminum thing on my own a few years ago. Wonderful for it! I also like it for keeping water out under a distributor cap. I know a fellow who uses it as starter fluid in cold weather. Anyone know much about that use?

Richard

also used it before to get the wasps out of the tube guards on a corn chopper. With the little red tube and a match.

WD-40 also works great if you ever have the unfortunate task of grinding aluminum.

JohnnyB ..

One reason that ball nose end mills bind and plug up is that the surface feet/min goes from what you calculate at the o.d. to about zero at the center of the ball. The center of the cutter is just smearing the material rather than cutting. I always rough out everything I can with a standard end mill and just use the ball end mill for taking out the final corner and bringing the slot to width. WD40 is worthless as a rust preventative and the best thing I have seen on the market is CRC3-36. Not many distributors carry CRC and I don't know why other than they do not have wide acceptance. I did read the test results from 5 major WD40 type oils and CRC beat out every one of them in every category. I order mine from a tool flyer catalog that appears here regularly.

TMD

We go through gallons of WD-40 in the shop. The main use is for cleaning. It is the easiest thing to use to clean the tacky way oil off the presses. In fact, we use it to clean the cutting and way oil off the tooling and machines. A spray bottle of WD is at every machine. It doesn't do squat as a rust preventive. It does work well machining the aluminum as you found out.
Les

Thanks much guys, as usual you are spot on. I did get an almost polished finish using the WD40. See there is such a thing as beginners luck.
JohnnyB

I was going to ask about what kind of lube is best for aluminum, but you all answered my question. Thanks. And to answer Richard Rogers question about WD40 being used as a starting fluid, I have used it to start diesels in bull dozers and trucks. I don't know if it can be used in a gasoline engine or not, I never tried it.

the metal doctor


Where did you read a review on different oils?

Don't forget that WD40 will totally screw up your woodworking projects that may come in contact with a machine table cleaned with it.
It causes fisheyes to form in the final finish. I know this is a metal site but some of you may use your shop for wood projects too.
Steve

Bossman, assuming you mean rust preventatives and not "oils" literally, click below link for review summary info -

www.practicalmachinist.com/ubb/Forum8/HTML/000042.html

One of the funniest things I have seen on TV was when Hank Hill could not get the cap off his can of WD-40 so he took his miniture can out of its holster and gave the lid a shot.
I THink WD-40's main advantage is convience. If plain old kero came in a spray can it would be as useful for most of what wd-40 gets used for.

any of u guys ever tried accu lube ???
some awesome stuff!!!!!
the link goes to a selection site for specific applications... a little pricey but they only reccommend like 3-4 drops per minute for alluminum in a mist sprayer.....
they say and i believe it is as close to dry machining as you will ever see.
never tried it????? try it you wont believe it.http://www.itwfpg.com/acculube/acculubes.html

You can use a lube on aluminum but it is not necessary. The reason the cut with a ballnose looks bad is that one side is conventional cutting while the other side of the endmill is climb cutting. To get a good finish just move off center a minimum of .001-.002 each way and climb cut the part. This will leave a superb finish without sacrificing any fit you may need. This would also keep the part being cut withinn the tolerance zone as .002 each way would only throw off the centerline by .001-.002.

Kevin