Aluminum Milling Coolant ( AGAIN!!! )

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.

On 03/21/2011 12:08 PM, Bob La Londe wrote: The machine is mostly made of aluminum with some steel parts.

Why? I use flood coolant on a mill that is steel and cast iron, and have had no rusting or other problems with it. I use Encool from Engineered Lubricants, it is totally amazing stuff, and I highly recommend it. No relation other than a satisfied user.

Jon

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?

Good water based coolant is actually a great rust preventative.

i

They are commecially use both in machining applications as well as in conjunction with supplied air respirators.

Because the manufacturer of the Metal Nibbler One says, "ABSOLUTELY DO NOT USE WATER BASED COOLANT ON THIS MILL." Aluminum is a very reactive metal and the majority of this machine is aluminum. (Metal Nibbler Two is about 95% aluminum.)

The short answer. "Cuz I ain't gonna."

I am not going to wash either of my little mostly aluminum mills down with water.

Did I mention that there is a cult following for water coolant guys almost as strong as the "WD-40 should never have been invented" cult.

I will most probably use a water soluble coolant on the Hurco when I get it going, but its 100% cast iron and steel. Not an issue amazingly enough for an iron and steel machine.

The following rant is not directed at any one individual:

Water is a no go for Metal Nibbler One or Two. So, given that I absolutely will not use a water based or water soluble regardless of how stupid I am and how smart you are and how superior water based coolants are and I'm to dumb to know any better I still ain't gonna, do you have good experience and recommendations with/for other options for milling aluminum?

Bob La Londe fired this volley in news:im8650$t0d $ snipped-for-privacy@news.eternal-september.org:

That would indicate an ignorance on their part of what's available in water-based coolants today.

I know some little bit about the reactivity of aluminum (being in the pyrotechnics business). Its reactions with water are a matter of constant attention in my line.

Simply by adjusting the pH of an otherwise non-corrosive water solution with a suitable buffer, one can reduce the reaction potential to nil. Most modern coolants contain such buffers, and are specifically designed for certain metals. Many are designed not only to not injure, but specifically to benefit the life and surfaces of aluminum parts.

I'd add that if a mill is designed to suck water up into the motor during use, it's badly (no, I'll say stupidly and negligently) designed.

I will research this "Metal Nibbler" thing. I want to know what to avoid.

LLoyd

LOL. I never typed a single word about it sucking water up into the motor. I did type that it moves a lot of air in a previous post. Its not the original piddly little 10K spindle either. This is a 30K spindle. I did express a negative about putting any flammable mist into the air in the presence of a brush motor. (one mfg uses ethanol as referenced in my original post) That comment has absolutely nothing to do with any type of flood coolant water based or otherwise, but interesting that you picked that out for some reason and misapplied it. If it moves air out one end, then by default air must move in the other end. Bad news for a flammable coolant mist.

Metal Nibbler and Metal Nibbler Two both bare little resemblance to their original forms at this point.

As to water based coolant. Again, I'm just not going to use it on my aluminum body machines. Maybe someday I may change my mind, but not in the forseeable future.

So purely as an intellectual exercise... assume that water is 100% not available in any form. What would you use as a cutting coolant/lubricant for milling aluminum.

As to seeking out this "Metal Nibbler" good luck. For a hint you might bear in mind that I call the Hurco mill Metal Nibbler Three.

I don't have a lot of experience, but recently I got a job as the CAD draftsman at a machine shop, and I was floored to find that there is even such a thing as water-based coolant.

WD-40 is fine for garage door tracks, squeaky front ends, and keeping your hand tools from rusting in the shed, but I used it once on an old, old model 13 or so teletype, and wound up having to disassemble the whole thing and clean the little parts in a lightweight solvent; it gums up, and I don't know if the solvent (in the WD) is flammable, but I presume it is.

On that note, I'd seriously recommend against using anything volatile around an open-brush motor that runs at such an insane speed - I can't even imagine a motor that would be capable of 30,000 RPM without flying apart! Or any open-brush motor at all; you don't want to cause an explosion.

For coolant, have you considered "liquid paraffin?" It's colorless, odorless, and used in those little candle-like mood lights, but I don't think the vapor would be hazardous.

Unfortunately, the only experience I've had cutting aluminum was at much lower speeds (like a couple of orders of magnitude) and the guy who was coaching/teaching me used lard; Crisco would also work there, but being more or less solid, it wouldn't be applicable for flooding.

How about non-detergent motor oil?

I don't really know much about stuff that's touted as "coolant," other than that they seem kind of expensive relative to ordinary stuff that you can find lying around.

Heck, maybe even "Mineral Spirits" or turpentine might be a possibility.

I don't know if this will be any help, but I wish you well; if possible I'd like to see videos of your new baby in operation. :-)

Cheers! Rich

Bob La Londe fired this volley in news:im87rq$6lj$1 @news.eternal-september.org:

Lard oil diluted with a low vapor pressure Stoddard-type solvent.

LLoyd

Bob La Londe fired this volley in news:im87rq$6lj$1 @news.eternal-september.org:

Oh... yeah you did. You said a mist getting drawn in might cause sparking.

Re-read your post.

LLoyd

Just avoid anything that says "absolutely no water based coolants". :)

i

I don't even care for it for most of those applications. It does seem to work ok for cutting aluminum though. Knowing the anti WD crowd will scream, I use it in the field for tapping steel sometimes too where it impractical to use a dropper of cutting oil. Its not great, but the pressurized cans do blow the chips out of the hole nicely. Yeah I know an oil can would do they trick, but I've bought a bunch of pump cans over the years and they just don't seem to keep pumping for very long.

It does seem to attract dirt when used in those type applications doesn't it.

Yeah, kinda why I dismissed all the mist type applications. The motor is self fan cooling and moves an incredible amount if air. In fact I honestly think it helps cool the cutter and work piece to some degree. Maybe I should design a motor mount that redirects the air flow through one of those vortex coolers. LOL.

No worse than any other candle or lamp fuel I imagine.

Crisco is awesome for that last finish pass on aluminum in the lathe with a rounded cutter to get that nicy shiny finish. I keep a tub in the frig out in the shop for pieces I want to look pretty. My wife was telling me that Criso is no longer animal lard though. I need to go look at my can in the fridge.

Basically a light weight ND oil is what I think most people used to use ages ago for most machining. Mineral oil is a pretty common ingrediant in cutting lubes too. I have read a ton of product labels. Whale oil was one of the old standbys, and jojoba oil is awesome too, but expensive to produce.

Not sure what mineral spirits is in relation to mineral oil.

New? This is just further incarnations on a theme. This particular machine is just the little Taig revamped again. I get consistent 60IPM if I want, but for virtually zero loss of steps I can run it at 50-55. For a little margin for error I set the max at 45, but increased the acceleration and deceleration. Now that I got the mass of that 12 pound spindle off of it, it really screams. A while back I put bigger motors on it with a little more torque. Eventually I'll get rid of the 20 tpi lead screws it came with and replace them with lower tpi screws which will allow me to take advantage of that increased torque and up my IPM for rapids again.

I did reread my post. A mist drawn in might cause an explosion if a flammable coolant was used, because a brush motor "will" have sparking. I guess I needed to spell it out more thoroughly. Figured most people would get that.

I can see though were it did look confusing.

As far as I know, you have two options:

1) Vegetable oil based mist cooling, which you may not like for many reasons. 2) A blast of cold air.

Both have powerful negatives. Mist coolant settles on everything in the shop and also spreads chips everywhere. Blast of cold air spreads chips everywhere.

i

FMI: It seems from what I have read about brush motors its actually worse in dry climates and brushes tend not to last as long either.

Vegetable oil in mist form is pretty flammable. Try shooting some cooking spray at an open burner on your stove sometime. LOL. So you don't think a moderate pressure flood oil coolant would work? Something like a 10 weight machine oil?

I don't think chips are that big of a deal. I've been sweeping up chips for two years. One of the reasons I didn't implement a coolant system on the mill(s) previously was because I didn't want coolant all over the place with those higher spindle speeds. Now that the one mill is in a bench top enclosure (have the base, but not sides built for the other little machine cabinet) I figured it was time to do something about that. Pete's suggestion about a vortex tube and a vacuum looks very interesting. My only issue so far is that the DIY versions I've found so far are pretty large. Simple to build though. The guy in the link I posted earlier is claiming 15C (59F) cooling out of his design. I can think of two or three minor modifications that should make it more efficient with about the same amount of air consumption. Not an expert on that of course. Just started learning about them a few hours ago.

A blast of cold air directed across the cutter and into a vacuum nozzle shouldn't spread chips everywhere.

=========== 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

for some commercial applications see 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).