The heresy of cutting oil?

[crickets]

One famous youtube machinist uses Isopropyl alcohol quite a bit for non-ferrous materials, seems like a decent idea for a manual mill, but I wonder if that would carry a risk of fire on a CNC machine with significant feed rates and a lot more heat at play.

 

[mhajicek]

I use Hangsterfer's 5080, mixed with DI or distilled water. It can sit for months without turning rancid, and I've gone years without changing it out. No rust, odor, or paint dissolving issues. I use it mostly on Ti and 17-4, but also occasionally on other stainless and aluminum. You can buy just a 5 gallon pail.

Not only does water have a much higher specific heat and thermal conductivity than oil, but when the heat capacity of water is exceeded it turns to steam, gets out of there, and makes room for more cool water. I had that going on with some aluminum yesterday. Oil, on the other hand, can burn, and leave insulating solid residue.

 

[Arc-On]

I use Hangsterfer's 5080, mixed with DI or distilled water. It can sit for months without turning rancid, and I've gone years without changing it out. No rust, odor, or paint dissolving issues. I use it mostly on Ti and 17-4, but also occasionally on other stainless and aluminum. You can buy just a 5 gallon pail.

Not only does water have a much higher specific heat and thermal conductivity than oil, but when the heat capacity of water is exceeded it turns to steam, gets out of there, and makes room for more cool water. I had that going on with some aluminum yesterday. Oil, on the other hand, can burn, and leave insulating solid residue.

Not to mention the sheer energy it takes to make the phase change from liquid to steam. If you're steaming out the water in your coolant you're removing an incredible amount of heat.

I worked at a large brewery for a few years and I continue to be amazed by the abilities of steam and heat exchangers.

 

[DocsMachine]

I have to admit I expected to see a lot more... shall we say, negative feedback.

The only reason I was considering the hydraulic over the proper cutting oil was just that it'd be nice to save about $500, if I didn't absolutely need to spend it.

Most of those problems go away with experience. I get no rust and don't have to adjust concentration.

-That runs kind of contrary to most everything else I've read. I've read a ton of posts about users finding rust stains under vises and fixtures, constantly having to adjust concentrations, and trying any number of biocides, including 'homebrew' ones like hydrogen peroxide and copper sulfates.

I'm sure that some people have the system figured out, and have no issues. In my case, the machine will be used infrequently enough even just the evaporation issue would make oil worthwhile.

HOw much coolant are you buying a year?

-It's not a question of how much. (The answer at the moment is "none". ) It's simply a question of the hassles of dealing with water-based coolants in infrequently-used machines.

Doc, I'm not so sure how it would work in a flood coolant environment, but diesel fuel works really well with aluminum[...]

-As does WD-40. I'm already a bit worried about the fire hazard of regular cutting oil, I think diesel might be going a bit too far.

On the fire issue, I'm not so worried about the oil or vapors, but I am heavily worried about the rags and paper towels. I've been running the 426 in the Omniturn for a couple months now, and while it's been working fine, naturally there's drips and drops I try to keep cleaned up. (I am the entire janitorial staff. ) And that can generate a pretty decent little pile of oil-soaked paper towels.

Probably going to need to get one of those metal flammable-materials trash cans...

Any way of getting a full drum hauled in unconventially?

-Not easily. I haven't done an exhaustive search, but the fact is, in this little area, there's basically zero manufacturing. No one uses soluble coolant, no one needs cutting oil, etc. (With the exception of the black, high-sulfur stuff used in pipe threaders, at something like $45 a gallon.)

Hydraulic oil is used extensively, though, and so I can get buckets of it, here and locally, cheap. If there was, as mentioned, a sort of "cutting oil additive package" I could throw in, even if it ran $30 or so, that's still cheaper than the real thing.

What ever you doo....always use oil with "Z-7" in it....or "Retsyn"....

-Z7 was for batteries, and Retsyn was for toothpaste. (And I knew both of those things off the top of my head. Longtime Python fan and I still have a couple of JC Whitneys floating around. )

When I worked for Doosan, we were telling folk in the strongest of terms to NOT use straight oil in the CNCs. In fact, it would void your warranty. We had several customers burn their shops to the ground because of cutting oil fires in CNC machine tools.

-Okay, was that prohibition because it could/would somehow damage the machine, or just because of the fire hazard?

I can easily see the fire hazard issue- a high speed spindle, on steel, with the reduced cooling capacity, could very well be an issue. Which is part of why I asked this question. My spindle maxes at 10K (Trak 2Op with the HS option) 99% of what I'll be making will be in aluminum, and a "big" part run for me might be 200 pieces.

On the other hand, the manual for my Omniturn suggests that cutting oil is actually preferable- fewer rust issues, considerably less lubrication issues, etc.

Upside, none of that maintaining concentrations or having to put in a bubble thingy so that it does not go stale.

-Again, that's the whole reason for leaning toward oil. No appreciable evaporation, no appreciable rancidity, no worries with tramp oils, no need for biocides or bubblers, no worries about concentrations...

I'm a small one-man shop operating out of what's basically a 2-car garage. The less of that sort of thing I need to worry about, the better. (Assuming, of course, the alternative is any kind of an adequate replacement.)

I think oil would be easier on the machine but I've never had a clear understanding why it was chosen for some applications and not others, other than the slow/fast thing and it smoking with the heat generated by carbide tools at speed.

-There's no doubt that for modern, high-speed manufacturing, a good soluble-oil coolant is by far the better choice. The cooler the part and tool, the better the dimensional stability, it's considerably cheaper (the 15 gallons of oil I'll need to fill the Trak will cost me almost $800, but even in the States would cost me over $300) and if properly maintained and monitored, works just fine.

In my case, it's mainly the 'maintained and monitored' issues.

As for the use of cutting oil, today you generally see it on things like Swiss Screw Machines and whatnot- and here, I have little doubt, a significant chunk of the reason is for machine lubrication. The cutting fluid also keeps the ways, slides, rods, axles and cams lubed, and I suspect that it would not last as long if fed soluble.

Kind of speculation there, but I'd be surprised if it were other than that.

Doc.

 

[crickets]

-As does WD-40. I'm already a bit worried about the fire hazard of regular cutting oil, I think diesel might be going a bit too far.

Diesel is probably less flammable than WD-40. Will put a note to self to compare the two this weekend

 

[Bill D]

How reliable is your heat and electricity? I assume oil would take a much lower temperature to freeze and break things.
Bill D

 

[SeymourDumore]

I think you maybe underestimating the capabilities of modern, premium water based coolants and putting too much weight on past experiences.
Garbage coolant of today is still garbage, but there have been significant research and advances made by chemists to eliminate most of the issues for top-of-the-line
brands.

I am sure everyone has his/her preference, as well as bad experiences with one, two or several brands.

I have kissed two frogs.
One changed it's chemistry and the coolant that was quite OK for 10 years became an oily, stinky, slimy mess.
The other was recommended by a machine manufacturer, but it turned everything not exposed to air black in a week or so.

Finally talked to the salesperson who actually was a chemist in real life.
I've switched to Chemetall 8 years ago for EVERYTHING! in the shop.
By everything, I mean machines used on a daily basis, machines used once a week or so and machines used once a month or even far less.
Absolutely no rust, no discoloration, no paint peeling/softening and any residue remaining on all surfaces after the water evaporated dissolves easily when coolant
is turned on again.

Again, This isn't an advertisement for MY brand of coolant, there are certainly many others that are equally or even more suitable.
It is simply a comment that there certainly are options today that can eliminate all of your concerns without the hassle of pure cutting oil.

 

[DocsMachine]

I would NOT use hydraulic oil as a coolant/cutting oil. It isn't designed for it, and you're asking for trouble.

-That's my exact question: What kind of trouble?

As above, I have no doubt that water-based is the superior product for most applications. There's a ton of reasons basically everyone uses it. (Cost, cooling, cleanup, no real fire hazard, etc. etc.)

But in my case, I'd prefer the significantly reduced maintenance hassles- if the use of cutting oil doesn't have it's own significant drawbacks.

Will oil- even or especially the "wrong" oil- give me poor surface finishes? Will I get excessive chip welding? Poor pocket flushing? Will the reduced cooling lead to shorter insert life?

I realize I'm kind of "bucking the trend" here- there's a YouTube video showing a 1917 movie about making shells for WW2- and even back then they were clearly using soluble coolants rather than oil- but again, if there's not a significant disadvantage to using it (well, besides the cost) I think it would be a preferable option for me.

Not only does water have a much higher specific heat and thermal conductivity than oil, but when the heat capacity of water is exceeded it turns to steam, gets out of there, and makes room for more cool water.

-One of the aspects I'm looking at here, is that I am not particularly time-limited. While I certainly hope that changes, at least for the moment I don't have to drive either of these machines at anything close to capacity.

I'm presuming that if a part gets too hot, I can slow the spindle and feeds down a touch- with most parts runs likely being less than 200 at a time, an even then likely only once or twice a month, a couple extra minutes per-part on the cycle time isn't a particularly big deal. (Yeah, I am a heretic. )

Yes, if my production increase, you bet I'll swap to soluble! But as things stand, I believe an oil will suit me better.

Oil, on the other hand, can burn, and leave insulating solid residue.

-Again, presumably that can be addressed with speeds and feeds. My parts are not large and won't require a great deal of hogging.

Cleaning afterward prior to sending off for anno may be a bit of a hassle, though. I know most anno shops have a rinse/desmut stage before plating, I was going to call mine to ask if sending in parts with a trace of oil remaining was acceptable.

Doc.

 

[DocsMachine]

How reliable is your heat and electricity? I assume oil would take a much lower temperature to freeze and break things.

-Shop's fully heated year 'round. Furnace would have to fail entirely for it to get below about 65F in there.

I think you maybe underestimating the capabilities of modern, premium water based coolants and putting too much weight on past experiences.

-Entirely possible, and why I asked this question in the first place.

My direct experience with solubles is near-nil, and based largely on reading posts here and on the other boards. For every statement that X soluble won't rust, won't go rancid, etc. it seems there's three more saying it will.

And I know that one of the keys to it is the quality of the water, where you want to use distilled/deionized. I'm on well-water, which is fine for drinking but kind of 'hard'- any time I'd need to add to a sump I'd have to go buy a couple jugs, or keep a cuboardful on hand.

Not a huge issue, in the grand scheme of things, of course, but still one of those little hassles.

Doc.

 

[SeymourDumore]

My direct experience with solubles is near-nil, and based largely on reading posts here and on the other boards. For every statement that X soluble won't rust, won't go rancid, etc. it seems there's three more saying it will.

And I know that one of the keys to it is the quality of the water, where you want to use distilled/deionized. I'm on well-water, which is fine for drinking but kind of 'hard'- any time I'd need to add to a sump I'd have to go buy a couple jugs, or keep a cuboardful on hand.

Not a huge issue, in the grand scheme of things, of course, but still one of those little hassles.

Doc.

Fair 'nuff!
Suggestion: Try one of the good brand's soluble first.. You only need a bucket, perhaps two.
If it fails, you still can empty it, evaporate the water and have little left over to dispose.

As for water, I have been on the same city water for all three coolants for 24+ years now.
(Swear that the guy dosing the chlorine into it is either too hung over or just simply trying to f@ck with everyone from time to time.)

 

[Garwood]

I have seen cutting oil run in modern CNC lathes and mills for special needs materials and it's a huge PITA to maintain and keep the area around the machine clean, but it does work.

It's a huge hassle and expense compared to water based. That's why people don't do it.

Do you have a chip spinner? How are you going to get the oil out of your chips?

I have run Trim E206 for 17 years because that's what two friends ran in their big shops and recommended. I have never had any go rancid and I have some that's been in machines for over a decade that rarely gets used. Nothing rusts with that stuff.

I don't know how straight cutting oil would work with a higher pressure system. I've only ever seen it gurgling out on machines that have it. All my CNC's, old and newer, have either come with modern multi-stage coolant pumps or been retrofitted by me. Higher coolant pressure is a big deal. I see cutting oil not working well at high pressures, but maybe I'm wrong.

 

[angelw]

Downside is that everything is oily. If the door opens and it drips some water on you this is different than if it drips some oil on you every cycle.
Bob

Hello Bob,
Back in the early 80's I had a Mazak Slant Turn 30 Mill Centre; it was the 2nd such Turning Centre that had live tools, delivered to Australia. The machine had a very long X axis slide with two turrets, one for milling and the other for turning. The Milling Turret was at the top of the X axis, with the turning turret approaching the part from below.

The product had a very deep, diameter 19.0mm hole that we used a Sandvik Ejector Drill system to machine. We started with Hocut soluble oil and eventually changed to a neat cutting oil with Sulfur and Chlorine, extreme pressure additives; the results were like chalk and cheese. It was very important that the swarf was broken into small chips to aid evacuation down the centre tube of the Drill System; one figure "6" chip and it was curtains for the drill and the drill rods. The neat oil improved chip control remarkably.

The coolant pipes for the Milling Turret, by design, had to come from behind the tool and squirted towards the door. A tooling sales guy that frequented our facility, was watching a part being run and when switching form Turning to Milling, the spindle would stop and then index to start position for the milling op. When this happened, there was quite a delay whilst the machine sorted it's self for milling and the sales guy, thinking the program was finished, opened the door to inspect the part. Just as he did, the milling tool started and the coolant turned on (typically no door interlocks in those days) and he was in the firing line for a high pressure blast of neat cutting oil. I'm sure you can imagine what that looked like with a guy in a suit.

Regards,

Bill

 

[DocsMachine]

Suggestion: Try one of the good brand's soluble first.. You only need a bucket, perhaps two.
If it fails, you still can empty it, evaporate the water and have little left over to dispose.

-I've been thinking hard about doing exactly that.

Only minor issue with that is, even on this board there's no real agreement as to which is the best (or in this case, most suitable) soluble, and in many cases certain brands aren't available in just gallons. (And that's part of my problem with the oil- it costs a fortune to get a bucket shipped up here. That 426 is something like $110 for the oil, and $150 for shipping.)

One other thing that's worth noting: The 2Op machine has an internal, drawer-style tool changer, which requires the work table to move full forward so it can open. The machine has a sprayer nozzle specifically to keep the rear way covers at least somewhat clear of chips, and I'm concerned with how well the more-viscous oils will work for that kind of "washdown".

I have seen cutting oil run in modern CNC lathes and mills for special needs materials and it's a huge PITA to maintain and keep the area around the machine clean, but it does work.

-Yep. As I said, I've been using it for a couple of months in an Omniturn GT-75, which, I've found out, is not the most liquid-tight of machines.

Now, admittedly that'd be an identical problem- if not more so- with water based, and unfortunately I have a poorly-sealed concrete floor so either one will soak and stain.

But on the lathe, I've been able to control a fair amount of it with drip pans and trays. There's not enough to try and recapture and return to the sump, but enough I don't want to end up with a "blast radius" stain on the concrete. (The operator's side has a wide rubber work mat, too.)

It's a huge hassle and expense compared to water based.

-That's kind of why I'm here. Basically, which set of hassles do I want to deal with less.

On one hand, I won't have to worry about evaporation, biocides, 'tramp' oil, skimmers, bubblers, evaporation or rust issues. On the other, there's the possible flammability, clean-up, reduced performance at the cutting edge, reduced cooling capacity and significantly increased cost.

Do you have a chip spinner? How are you going to get the oil out of your chips?

-For the time being, actually, I have a double garbage can. I bought a pair of large Rubbermaid trash cans that can 'nest'. I drilled a couple of 1/4" holes in the bottom of one, and slip it into the other.

I dump my chips in there, and after a while, a fair portion- though not by any means all- has dripped through to the bottom can. And the recycling place doesn't seem to care if there's a little oil on them- presumably as long as it's not actively dripping off.

That's another one of the things that kind of helps let me get away with this- I don't, yet, produce much by way of chips. It took me a month with the lathe alone to fill the can once. What will I do if/when production increases? Not at all sure, having a hard time seeing much past spring, at the moment.

I don't know how straight cutting oil would work with a higher pressure system. I've only ever seen it gurgling out on machines that have it.

-Curious about that, too. The 426 in my Omniturn seems to work quite well, and I happen to know that pump can't produce more than 5 PSI. How well it might work in the Trak is still quite the unknown. I'd be surprised if, at least as a working fluid, it doesn't perform as well- I suspect they both use very similar "Gusher" style centrifugal pumps.

Doc.

 

[CarbideBob]

As for water, I have been on the same city water for all three coolants for 24+ years now.

I'm on a well. I filter, soften and filter it again. Had a deionizer setup for coolant and part cleaning but found no advantage so dropped that cost.
Local GM plant was on Flint city water forever. Then the water changed and rust and other problems. Changed over to Detroit city water at large cost.
This before the lead pipe problem known here at all. Maybe a canary in the coal mine.
If you run most water based you have to check concentrations often and keep air in it. The bigger problem is a refractometer will not tell you when the additives are worn out.
To know this you have to send samples to the coolant company every few months and they will send you a little bottle of this or that to add.

In a big plant coolant is checked and logged every day and usually on each shift with the simple read. One a week or two each goes off to lab.
As a supervisor if any of these went out of the control limits I would get a nasty email and have to answer.
More than one team leader got written up for not making the right adds or "pencil whipping" the daily checks.
Bob

 

[CarbideBob]

I'm sure you can imagine what that looked like with a guy in a suit.
Bill

LOL,
My experience. The days when you wore a three piece suit to go see customers.
Walking through the shop and they are emptying out the big central with a 3 HP pump to do it quickly as I walk by.
The exit hose comes flying out and carbide sludge water from head to toe.

 

[Pete Deal]

I hate these coolant discussions. Everybody's got a latest and greatest coolant (talking water soluble now) that is 10x better than the old. Local buddy, same way. New coolant, then the bitching comes when the honeymoon ends.

I have run Trim E206 for 17 years because that's what two friends ran in their big shops and recommended. I have never had any go rancid and I have some that's been in machines for over a decade that rarely gets used. Nothing rusts with that stuff.

I sent Doc a PM because I didn't want to wade into this but said exactly this ^^^^.

Not 17 years in my case only 5-6. But I've never changed it, and it never stinks. At least it doesn't stink to me. My wife hates the smell but to me it just smells like a good day in the shop. My Mazak fits Doc's description some- sits a lot. Yes it ought to have a skimmer. But, it doesn't. Looks nasty with all the way oil on top. Works great! Never any rust. I have had some foaming issues and usually it's because I got too high concentration or the pump is sucking air. Can't blame the coolant for that. It is green though so it's not a good candidate for Instagram videos which seems to be the main goal of many- got to have a coolant that looks good on TV.

I do have a little home brew RO system that I use for top off water. Made it with ebay parts.

 

[HappyWyo]

A lot of opinions on this forum, but how many of the authors own thier own machines? Do you want your machine to last decades of just a few years? Do you actually create that much heat when milling aluminum?
We use hydraulic oil-diesel fuel mixture in all of our machines with hydraulic filters on each machine., lathes, mills - horizontal and vertical, shaper, and CNC. We use lard for cutting threads, machine or manual. Water with the grinders.

 

[hvnlymachining]

We use petroleum oil with lard oil added in all manual and cnc machines. When switching between sensitive materials and certain ops, no coolant change is necessary.
( Gun drilling for instance and flammable metals) as far as heat transfer, look into your machinery's handbook, it gives a good explanation.

 

[Cole2534]

Aluminum and looking for an out of box solution?

I'd go MQL combined with a shop vac, for chip evacuation. Depending on your table size it could probably just ride around on there.

Programmed via Mazatrol

 

[CarbideBob]

Aluminum and looking for an out of box solution?

I'd go MQL combined with a shop vac, for chip evacuation. Depending on your table size it could probably just ride around on there.

Programmed via Mazatrol

Is this to say MQL and aluminum cutting has worked well for you?
Not trying to be an ass. This a serious question.
Bob