Thread: General-Purpose Oil-Based Coolant for VMC?

I'm looking for recommendations for cutting fluid for my VMC. Usage is highly intermittent (2-10 hours at a time, once or twice a week), so soluble-oil coolant is very unappealing (I've also cleaned sumps before, and would rather do without coolant than do that again). I machine a decent amount of aluminum and 316 stainless, but also some titanium, pre-hardened 4140, and pretty much all of the engineering plastics (teflon, UHMW. HDPE, delrin, etc). I figure I can cut the plastics dry. I do a decent amount of tapping, mostly threads from 4-40 up to 3/8-16.

Speed is not a huge issue. I am primarily interested in longer-lived cutters and smoother cuts. No oil-based cutting fluid is going to have the cooling power of a soluble oil coolant, especially for high-hp cuts in aluminum, but that's not a problem for me.

Thanks in advance for any recommendations, or links to resources.

Newer soluble oil coolants can sit for several months at a time with tramp oil on top without any Monday morning stinkies. Blaser Vasco 5000 is one example of a soluble oil coolant that can sit without stink and works pretty good too. I like it. No, I am not a salesman for them.

Neat oil is great, but you also have to have a way to wash it off the parts afterward, which can be a PITA in itself depending on your facilities.

The semi-synthetics, full synthetics and soluble oils can last for years actually, with simple attention to concentration, mixing method, and tramp oil control.

I have only a home shop with a manual lathe, a surface grinder and a bandsaw that have flood coolant systems. Each has had a full synthetic coolant in them, the lathe for four years and the others for 1.5 years. The full synthetic in the lathe (which I wouldn't buy today because of the cost now) is a TriCool "TC-1". I've skimmed off a little tramp way oil and perhaps tapping fluid once, using an oil-absorbent pad. That was about a year ago when I replaced the 40 year old coolant pump that finally failed.

The grinder and the saw have ValCool VP910 in them for over a year now, with no signs of trouble. The machines are lucky to see 10 to 20 minutes of coolant run time per quarter. There are no aerators, skimmers, pumps, biocides or other additives at work here. I just keep the top clean and accidentally hit the pump on about once a month. I lose volume to evaporation of water, so once or twice a year I top it up with a 2% mix.

I know that a CNC vertical machining center is likely to push out more way lube and may need a skimmer and/or aquarium pump aerator. You use it enough that this may not even be needed. Just keep the top of the tank clear of a choking film of oil, and get a refractometer. Use the proper correction factor for the coolant product you choose (given by the maker), and be sure to mix using the mantra of "O-I-L", meaning Oil In Last, add the concentrate to the water. Never run it any richer than the the recommended concentration, as that can also start a festering bacteria and stink.

Simple steps and easy maintenance will result in very satisfactory performance of most any product. Pure oils are VERY expensive to load a machine like that, and little benefit is gained.

You guys can make these sensible arguments all you want, but these old timers aren't going to change their ways. I cannot understand why anyone would want to use straight oil. What a mess.

Go read the thread about bacon fat. Render some of that and fill up your sump. That should smell delicious.

If you are worried about trap oil, just use way oil for lube.

Hangsterfer’s Hardcut would be excellent for you.

Beacon Lubricants Inc.

Is local, and is used in a bunch of shops around here.

Shipping may be a deal breaker though.

We use these oils(426 and 423) in our screw machines and CNC lathes. They may may be a little messier in a mill, but not too much, as I know of an old timer over here using them in his mills. We used to use the 426 and the last drum we bought is the 423, so the oil in all the machines is a blend. These oils are non staining and will cause no issues with plating. High sulfer oils can cause corrosion and plating issues with brass. If you make a lot of chips you will want a chip wringer as only a fraction of the oil will drain off even even over a years time. The information below is coppied from a year old email so prices may not be current.

Mobilmet 420 Series
Mobilmet 440 Series
The above links came from Mobil, but we do not know what that 440 series is.
Just got off the fone with Johnson oils and Omnicron is now 426 and Nu is 423, both are $14.62 a gallon in 55 gal drums.

Oil is OK in screw machines and some milling operations. As soon as cutting speeds get up to the range required for optimal productivity of modern day tooling, oils can get very dangerous because of the lower flash point. I would never run water-based coolants in CNC Swiss type screw machines (tried it once), but then I'd really hesitate to run pure oils in a machining center if I was machining steels at high speeds.

If the machine only runs once or twice a week I'd look at one of the "minimal" lube systems. I use a Trico Micro-Drop and I like it a lot, I think the name of a company making a competing system is called Acculube. They use an air blast that has "micro drops" of a special lube but it doesn't create any mist at all.

The main limitation of these systems is during heavy hogging your part temperature can rise more than it would with full coolant which can cause tolerance issues, but if you can live with some "cool off" periods these systems might work out for you.

One issue on the Trico system, they offer both a vegetable based and synthetic based oil for the systems. The veg one works well but any leftover dries to an amazingly tough and ugly brown coating on tooling and parts, kind of like burnt oil on a skillet. I switched to the synthetic oil and that problem went away.

Paul T.
Power Technology

Thanks for the advice, guys. My original inclination towards oil-based cutting fluids was due to the suggestion of the shop where I bought the mill (micro-machining facility doing difficult materials). However, it sounds as if most modern coolants, if mixed properly, will be fine for intermittent use. I should add that idle periods for up to a month are possible with this machine (extended period of working plastics, for example). To be clear, my machine is a '91 Makino, and I am not doing high-performance roughing with advanced toolpaths and the like.

The skimmers at past shops didn't work particularly well. Are there skimmers which will handle trap way oil better than others? The coolant tank on my machine is exceptionally difficult to reach, so manually clearing trap oil will be difficult, for sure.

I have used micro-drop coolant systems on a manual mill in the past. I wasn't in love with the cloud they produced, which I would guess gets worse in full-enclosure. Paul, you are saying this system doesn't do that? If so, that is certainly tempting.

It seems like straight oil vs. soluble oil breaks down like this:

Straight Oil:
-dirtier parts
-more expensive
-low-maintenance cutting fluid
-more wasted fluid in chip disposal
-poorer heat removal and chip clearing
-superior for tap lubrication

Soluble Oil:
-cheaper
-cleaner chips and parts
-higher-maintenance due to tramp way oil and the like
-more bacterial activity (chance of infection with use)
-better chip clearance and heat removal from cut
-more likely to cause corrosion and damage in hard-to-dry places

Am I missing anything? The maintenance is still a big concern of mine (due to access issues and low usage), but otherwise soluble oil seems like the correct way to go. It sounds as if oil-based cutting fluids are used exclusively in screw-machine style work, most likely with a vastly higher fluid volume than I will use. It sounds as if ValCool VP910 and Blaser Vasco 5000 should work reasonably for me. I presume these could be found at MSC or the like. Still, the Mobilmet 420 and 400 series look like very good fits for my application. My biggest concern with them is oil loss in chips.

Thank you guys for your guidance and patience with my basic questions. It is extremely helpful.

Originally Posted by ewlsey

You guys can make these sensible arguments all you want, but these old timers aren't going to change their ways. I cannot understand why anyone would want to use straight oil. What a mess.

Go read the thread about bacon fat. Render some of that and fill up your sump. That should smell delicious.

If you are worried about trap oil, just use way oil for lube.

Ewlsey, I'm undecided whether I should be honored or offended by you calling me an "old timer", but regardless, your tone is belittling and comments unhelpful. If it means anything, I'm not an old timer. I've been at this for less than 10 years, starting at age 15. I've learned most of what I know from people unlike yourself, who have the kindness to help others who ask for it.

Originally Posted by Halcohead

Ewlsey, I'm undecided whether I should be honored or offended by you calling me an "old timer", but regardless, your tone is belittling and comments unhelpful. If it means anything, I'm not an old timer. I've been at this for less than 10 years, starting at age 15. I've learned most of what I know from people unlike yourself, who have the kindness to help others who ask for it.

Agreed, my comments were out of line.

This selection of cutting oil seems to be the area where machinists stop caring about science and logic, and fall back on wive's tales and incantations. There are hundreds of suitable water soluble coolants being used in thousands of shops. Yet, on this board, I read about: bacon fat, canola oil, used motor oil, high sulfur oil, mineral oil, etc. being recommended.

The soluble coolants we have now are the result of research and testing. They have limitations, but are much better than the old oils for most applications, especially cooling, which is the purpose of coolant.

I have used an Acculube MQL system for some time on an open toolroom mill. As has been mentioned, there are differences in the oil: the Acculube synthetic dried to a hard varnish, but the Trico MD-7 seems to never dry. The Acculube system will not fog - the droplets are large enough to hit the surface and stay there. There is very little mess even with a completely open mill, just a very light film right where you were cutting. The amount of oil used is extremely small - in the use you describe a gallon will last you at least a decade. There is about a 1 cup reservoir, I have to top it up once a year or so - not kidding here.

It works pretty good for milling aluminum, though you do have to allow cooling for dimension control. Lacking anything else, I used it for drilling and on SS too, but it is not so good there. It does not remove chips as well as a good blast of coolant (and yet blows them all over, too) and does not seem to cool well enough for stainless. I had to run about half the sfm and half the feed rate in SS, so 1/4 the MMR, and even then tool like was not good - not so much from wear but chipping the carbide from recutting chips. Drilling in SS is a real challenge, if you run the drill hard enough to actually make chips it is almost impossible to keep from overheating unless you peck maybe 0.1 and then dwell at the top to cool.

Now with a VMC and a good coolant system I can see the advantage. I can cut aluminum faster and SS much faster. Drilling is much better. Tool life in aluminum and particularly SS is much better.

I suggest you get a small sample of several coolants you are considering and see if you like the smell, the way it dries, etc. This was my first machine with flood coolant, I read all the info I could find and then got samples of 2 Blaser products and a couple of others. I smelled them, felt them, rubbed some on a vise and left it there. The Blaser 20 was OK, but smells somewhat perfumy. The Blaser 940 smelled downright awful, dried to a hard varnish, rusting the surface underneath. Trimsol 206 looks - and smells - exactly like the blue stuff in a portable toilet, and dries quickly to a gummy residue. I settled on Koolrite 2290. It has almost no smell at all, takes a long time to dry up (longer than Blaser 20), washes off easily (before it dries, which takes 6-8 weeks), and promises long sump life. I use the machine exactly as you describe, a few hours at a time, with gaps of days or weeks between use. So far (after only four months) the sump seems fine. The only trouble I have with it is that with my somewhat soft water, it foams in my quite active coolant system. Koolrite's antifoam additive kills this immediately and completely, but as I add makeup water and coolant, it comes back and needs more additive.

The P.O. of my VMC used Vasco 1000, a veggie based Blaser product (I think now superseded by the 5000). Based on the mess left behind, and the damage to paint and plastics, I would be very wary of Vasco or any veggie based product.

I hope that helps some.

On coolant versus cutting oil it is not all new science versus old dinosuars. Yeah coolant will win hands down in cooling. It has water boiling off carrying the heat with it, which is now humidity. This causes personal discomfort in the summer as well as rust on things far away from the machine. Collets, sleeves, spindles, paint on the machine, linear bearings all seem to last longer with cutting oil. I have been exposed to some bad ones in other shops (clorinated and high sulfur) that did affect my health. That is why I use the ones I do now. The anti misting Mobil oils stay on the machines. I have seen some discussion of coolants causing some of the PM members to smell after they have thoroughly bathed. Seems to me that it is being absorbed through the skin. I sometimes use pour on insecticides on my cattle. The stuff will kill flies that bite the animals for two weeks. It is absorbed through the hide and they cannot be sold for 1 month after the application. Are all the water soluable additives tested with every possible food and medicine combination that a machinist could ingest or use? Maybe they are that good and safe, but how would we know? Halco is doing the right thing in weighing pluses and minuses. It is not all black and white. Yeah, I have seen some of the demos where thay are running incredible speeds and feeds. You could not do those with oil, but I do not live in that world. I just watch those videos and say WOW!
Halco, on oil use, you will reclaim a lot by draining the chips. But you will use a lot less with a wringer. If you sell chips most buyers will complain about the oil if you do not wring em. We used to use a drum every couple of years. The last drum we bought as Mobil Met Nu and I do not think they have used that name for about eight years now and I still have half the drum.

Yep I use oil in all my cnc's & screw machines, never have to change out just add some no rusting & the machines last a lot longer.
wash parts in Naphtha.

Two things: I wouldn't recommend a full synthetic (like the ones I use) in too many machines. The concentration needs to be monitored more carefully, and the PH level can cause machine paint and rust problems if you're not careful. I chose it only because I needed the longest possible sump life, the cheapest start-up cost, and I can watch it.

Oils are fine in many machines, but can be completely wrong in milling machines that run modern coated carbide tooling at high speeds in steels, stainless steels and superalloys. The smoke, smell and fire risk can be enormous. I'd suggest one of the better semi-synthetics. It'll have higher lubricity. Look for "tramp oil rejection" as a desired feature.

Originally Posted by DobermanDave

Yep I use oil in all my cnc's & screw machines, never have to change out just add some no rusting & the machines last a lot longer.
wash parts in Naphtha.

This is what I am saying. How do you know the machine lasts longer? Have you done a side by side comparison of machine life?

If you machine aluminum, you will have to change coolant/oil regularly. The fines will clog up all of the nozzles and strainers.

Or maybe you just invest in some good filters :-)

I run my Haas VF2 intermittent too.I use the Blaser coolant line.I also supplement it with Triadine 20 which is a Microbiostat.This prevents bacteria,which prevents infections and stink.Haas does not use much way oil,so I do not use skimmer,not needed.I sometimes do not use machine 1 to 2 weeks at a time.When I do it is nice not to have stink.When doing Hogging with big endmills it would be nice to have a mist collection system though.Have not seen or felt any negative effects of coolant mist though.I also add a little Rug Doctor in the mix.That prevents any foaming,especially when really hoggin out material.About 1/4 cup is all that is needed.Then you can see through the window also.

Originally Posted by ewlsey

This is what I am saying. How do you know the machine lasts longer? Have you done a side by side comparison of machine life?

Well I have a 1992 CHNCI I bought new & it will still hold .0002 all day long. I have looked at others for sale that were totally
trashed because they ran Toilet water, the ball screws had a lot of slop, air valves all stuck up. Question would you fill
up your car motor with water coolant?

If you machine aluminum, you will have to change coolant/oil regularly. The fines will clog up all of the nozzles and strainers.

I have filters for that.

Originally Posted by DobermanDave

I have filters for that.

You must not do much aluminum...