Aluminum Milling Coolant ( AGAIN!!! )

Ok, here we go again. The cabinet for Metal Nibblers One is complete, and I am ready to add coolant. (Ok, I still have not made a door for it. I've
got sheet plastic spring clamped across the front.)
I've got misc accumulated hardware (pump, locline, barbs, hose) and can make other stuff as needed.
I favor flood cooling. Mist cooling scares me for most coolants, and I can't use water based coolants. I'm turning up to 30,000 rpm with an open brush motor. There is a lot of air moving just from the spindle motor, and there is a potential for sparks if a mist gets drawn into the motor. The machine is mostly made of aluminum with some steel parts. Makes water based a no go.
Options: Regardless of what some say WD-40 makes a pretty fair coolant/lubricant for cutting aluminum. (There does seem to be a cult following of people who hate WD-40 unconditionally.) Fairly high flame risk, but maybe not for flood cooling. $20/gallon
Transmission Fluid. I have no real knowledge of this. I've poured some on a part to see and it seems to cut ok, but for short runs dry cuts ok too. I have to wash it off with Dawn dish soap, rinse and repeat to get rid of the oily feeling of the final work piece. Haven't really given it a fair shake as a continuous flood coolant. $15-20/gallon
Hydraulic Oil. No kidding. One local production shop who's owner is a fishing buddy of mine suggested that I just go buy 5 gallons of hydraulic oil over at the local Sam's Club. $Have not checked price
Diesel. The smell gives me a headache. I do have 50 gallons of diesel on hand to fill my tractor and its probably the cheapest answer. I have not tried it due to the headache factor. $4/gallon
Commercial cutting oils. ??? Never bought any other than the small bottles I use for threading manually. $(priced all over the spectrum)
High tech option (not really): One of the super high speed machine makers says they setup their machines to spray mist ethanol. Claim they get incredible cooling with it, and I can believe that. $(can't even find it for sale in bulk, do not want a flammable mist anyway.)
Not an option: Water based and/or water soluble coolant/lubricant is not an option. There seems to be a certain following that thinks water based in the only answer to everything as well. Not for two out of three of my machines it isn't. It's a no go.
I am really pushing my speed for a small machine, and may go faster. For small circular pockets it can really shake the work bench. I bolted it through the cabinet through the table surface, and added full length sheets of plywood to the sides and back to brace the table for those types of cuts. I may have to make a different more rigid work bench for it eventually. The plywood on the sides did make a nice place to add heavy drawer slides though. No I have a place for all those bits, mills, and tools that I only use on that machine. LOL.
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Bob La Londe wrote:

<snipped>
The answer to your issue is air, not liquid. Your best option is to buy or build a vortex tube cooler and use chilled compressed air for cooling and chip evacuation. Ideally have a vacuum nozzle located opposite the air nozzle so that the chips are blown into the vacuum and have less chance of getting into your spindle motor.
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On 3/21/2011 10:47 AM, Pete C. wrote:

Is it really vortex or just expansion chamber?
Seems if its expansion chamber then I could turn one on the lathe pretty darn quick out of aluminum rod stock. Maybe add aluminum cooling fins to the first part of the nozzle to assist. Also remember my shop is in the Sonoran Desert. Temps in the shop over 100F in the summer are common from the end of June into September. Is an air cooler really going to get cold enough to make a difference?
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Bob La Londe wrote:

They are commecially use both in machining applications as well as in conjunction with supplied air respirators.
http://en.wikipedia.org/wiki/Vortex_cooler
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On Mon, 21 Mar 2011 11:15:06 -0700, Bob La Londe

==========Big difference.
A vortex or Ranque-Hilsch tube splits an incoming gas stream into two output streams, one hot and the other cold. An expansion chamber simply expands and cools the gas because of expansion and outputs a single stream.
for more on this see http://en.wikipedia.org/wiki/Vortex_tube
for some commercial applications see http://www.exair.com/en-US/Primary%20Navigation/Products/Cabinet%20Coolers/Pages/Cabinet%20Coolers%20Home.aspx http://www.stream-tek.com/products/vortextubes/vortex-tube.php?gclid=COKnnei34KcCFZFoKgodciSg_A http://www.vortec.com / and many more
-- Unka George (George McDuffee) .............................. The past is a foreign country; they do things differently there. L. P. Hartley (1895-1972), British author. The Go-Between, Prologue (1953).
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On 3/21/2011 1:56 PM, F. George McDuffee wrote:

http://www.exair.com/en-US/Primary%20Navigation/Products/Cabinet%20Coolers/Pages/Cabinet%20Coolers%20Home.aspx
http://www.stream-tek.com/products/vortextubes/vortex-tube.php?gclid=COKnnei34KcCFZFoKgodciSg_A
I already saw some of the Stream Tek ones online today. They claim a pretty incredible temperature differential. I just might buy one of theirs if I go that way. The price seems pretty reasonable. Not sure about the CFM requirements though. Their medium unit just says requires 80 PSI. I need to look further and see what their CFM is.
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On Mon, 21 Mar 2011 15:54:38 -0700, Bob La Londe

They use A LOT of air and are damn noisy. If you want one, I'm pretty sure my son still has a unit that he'd let go.
Karl
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Karl Townsend wrote:

I'm pretty sure his 30k spindle milling aluminum precludes vortex chiller noise as an issue.
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wrote:

You do have to speak up when standing next to it to have a conversation, but when I have a job going I leave my office door open to listen for the metal on metal screams of a crash. My office door is about 25 feet away and sound attenuates exponentially with distance (or so they tell me). I can have a conversation on the phone just fine with the door open.
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wrote:

I'm sorry I didn't follow this thread, but how in the heck do you use liquid coolant with a 30,000 rpm spindle? Unless something has changed in high-speed machining, that's typically done dry -- even in steel, where, of course, they use high-performance inserts, many of which *can't* be run with liquid coolant.
In production machining at those speeds, it's dry, near-dry, or lean-mist vegetable oil. In aluminum, it is (or was) dry, period.
--
Ed Huntress



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wrote:

Well, the one reference to ethanol coolant I made early in this thread was on a 60,000 to 80,000 rpm machine.
30,000 rpm is not all that hard to achieve nor is it some magic number, or even expensive if you can stand a certain amount of run out. Heck, even Harbor Freight rotary tools turn at 15K and they aren't very expensive at all.
A lot of the high speed (commercial) stuff on You Tube uses what looks like water soluble or water based flood coolants.
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wrote:

Yeah, I sold Roku-Rokus, with up to 36,000 rpm spindles. And we ran one in our shop.

Jeez, I'll have to look sometime. Those must be awfully tiny cutters, if they can use coolant without throwing it off before it gets to the cut.
--
Ed Huntress



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"Ed Huntress" wrote

Who says the coolant is at the actual cutting interface? It could be pulling all heat from the material ahead and behind the cut.
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wrote:

I suppose so, but why would you pull heat from *ahead* of the cut?
With aluminum and most advanced cutter materials, you don't begin to approach the surface speeds that would result in unacceptable temperatures, with any cutter than you can spin at those speeds. And power rarely is a problem, so reducing cutting forces doesn't mean much compared to machining steel.
Teeny cutters are typically made from micrograin carbide. When used in aluminum, they're often diamond-coated, especially for use in modern automotive castings and other precision castings, which are hypereutectic or nearly so, and abrasive as hell. Those cutters can take a lot of heat.
I usually skip over the "which coolant for aluminum" threads because, like this one, they generate a lot of ideas going off in all directions. But, for the record, the basic idea is that you don't need coolant for most applications, at least, to keep the tool cool. You will get a small improvement in tool life using a good lubricant. But, traditionally, coolants haven't been used. Kerosene was used as a lubricant in the first half of the last century, mostly to improve surface finish, but sometimes to deal with edge build-up problems. That became a bigger issue with carbides.
Lubricants, and coolants to some degree, can reduce edge build-up, which can be a problem in some applications. In milling with carbide tools, however, the primary use of soluble-oil coolants has been for chip control, particularly in small-shop and batch-production applications.
But, as always, I'm behind on the thinking in many facets of machining. I use HSS for almost everything, so edge build-up isn't a big issue for me. And my hobby projects are machined mostly in 2024 T4, which I get as scraps, and that alloy does not present much of a build-up problem for me, on my small lathe. I use a lot of positive rake on aluminum and I make sure the edges are sharp and the chip-flow area is smooth.
--
Ed Huntress




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Ed Huntress wrote:

If you really want to cool your tool
http://www.academypublisher.com/ijrte/vol01/no05/ijrte0105055059.pdf
John
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wrote:

Jeez. It must be *really* tough to find a good research project for PhD's in manufacturing engineering these days. d8-)
--
Ed Huntress



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Ed Huntress wrote:

Perhaps but there is real interest in machining Be, plutonium and those sorts of things in inert environments these days. Know what I mean, Jelly Bean? LOL
--
John R. Carroll



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wrote:

But those guys are all Indians. They already *have* that stuff.
Maybe they're opening up some new market in the Third World.
--
Ed Huntress



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Ed Huntress wrote:

You know the difference between an Indian and a Pakistani? I think the guy with the Typo Dong Dong's is still looking.
--
John R. Carroll




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They make different kinds of a-bombs?
--
Ed Huntress



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