Want to use oil as a coolant

After hearing and seeing what water soluble coolants can do to machines, I'd like to use oil instead, but which oil? I'm cutting mostly brass and aluminum, and occasionally steel. Would something like WD40 work? If not, what would?

WD40 is not a good idea. A bit too volatile.

There are some very nice "Cutting oils" Not overly loaded with sulfur.

The screw machine guys use them, I've used them,,, The machines love them.

Linky

Cutting Oils

borne2fly said:

After hearing and seeing what water soluble coolants can do to machines, I'd like to use oil instead, but which oil? I'm cutting mostly brass and aluminum, and occasionally steel. Would something like WD40 work? If not, what would?

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You make no mention of what machine.

Hardinge toolroom lathes run oil. Larger lathes running oil will start a fire. CNC mill--some can run oil or coolant. The chip management will be different from coolants to oils. Also, with oil, you need a copious amount of fluid in the cut, otherwise, you get fires.

Also, with oil, you need a copious amount of fluid in the cut, otherwise, you get fires.

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Probably explains why the biggest Bullards have 400 gallon coolant tanks.

I'm also tossing up between cutting oil and soluble coolant on a couple of my machines (another lathe and a small mill). Other than the cost, is there any disadvantages in using cutting oil over soluble coolant. I understand that the soluble coolant will provide better cooling over straight oil but can't really come up with any other disadvantages. On the other hand I can see quite a number of disadvantages in the coolant. Are there any special considerations with regards way lubrication when using cutting oils? The lathe is brand new (and no, NOT Chinese or any other Asian country for that matter), so I really want to look after the bed as best I can.

Pete

I used oil for a several years. It was 20+ years ago, 'wish I could recall the brand
It did NOT serve double duty as paint remover! like the advanced synthetic soluble oils did

But its....oily!\\

Everything around gets ....oily

YOU get oily....

Somehow...on the HLV...it seemed OK ;-)

Small SS parts, low qty, High value

I run oil it is a cutting oil that I buy in 5 gallon buckets from a screw machine shop. I use it in my K&T mills and in my W&S lathe as well as my saw. It is messy but your cutters will last forever and it leaves a great finish.

There are several series of dual- (and triple-)purpose straight oils intended for use as cutting, lubricating (and hydraulic) oils. Modern ones are designed for minimal misting/smoking, non-staining of yellow metals, and minimal chlorine (and other disposal nuisances). They are most often used on screw machines that can't tolerate water-based coolants.

The Mobil Mobilmet 400 series is one example. (This replaces an older series named with greek letters like Omicron and Sigma.) Oils in this series are available in several viscosities. I happen to use Mobilmet 426, which is toward the thicker side. Chevron Bright-Cut NM and Citgo Autocut NC 425 are comparable products.

Note: not all dual-purpose oils are non-staining of brass and aluminum (low or no active sulfur), or non-chlorinated (alternative EP additives) so make sure you check for those properties if they're important to you.

On occasion, I have seen Mobilmet 404 (a fairly light oil) on sale at Enco. McMaster-Carr carries Mobilmet 426 and 766. For other dual-purpose oils, you will probably have to order through a local oil distributor. A good distributor will work with the oil company sales reps to figure out some specific recommendations for you.

Straight cutting oils have a few negatives.

-Lots of smoke produced during agreesive machining of aluminum and most all machining of steels. (at least at carbide speeds)

-Risk of fire, I have seen many small fires caused by cutting oil being ignited by very hot chips, normally cause some sort of tool falure while turning stainless. I also once saw the entire enclosed area of a medium sized VMC filled with oil mist combust in a amazingly bright and quick flash fire, which after nearly giving the operator a heart attack, immediatly went out.

Of course fire is much less likely on a manual machine... most I have seen are caused by cnc operators not paying attension.

-In large quanties the initial cost is very high, though oil does not require a lot of maitenance

-Eventually all of your clothing will be covered in oil, which when washed, will get on your wife's clothing.... Whose reaction will probably make the rest of the problems not seem so bad.


-Other people touched on the inferior cooling ability, the mess and the smell.

Eventually all of your clothing will be covered in oil, which when washed, will get on your wife's clothing.... Whose reaction will probably make the rest of the problems not seem so bad.

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Don't forget your shoes... I wouldn't suggest wearing expensive shoes, unless you rubber-band plastic bags around them.

I'll add to the list of negatives:
1. Disposal
2. Safety - read the MSDS before you buy it

S_W_Bausch said:

Don't forget your shoes... I wouldn't suggest wearing expensive shoes, unless you rubber-band plastic bags around them.

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No expensive high heels in the shop? Bugger!

Regarding safety, I presume there aren't any particular risks with modern cutting oils and the smoke/fumes they may create? At the moment I will typically just use Tapmagic when parting or when I want a particularly good finish, but I often wonder about the safety of the smoke involved.

Pete

If you mean coolant you brush on or squirt from a bottle you can use any amount of any kind you can conveniently clean up. WD40 is a great coolant for aluminum but it's no good as a general purpose coolant or lubricant.

If you mean flood coolant and you have a small home shop I don't reccomend it. For one thing flood coolant always splatters unless you have a full containment chip shield. For another in a low production home shop you don't get much benifit over locally applied coolant. See, the main beneffit of flood coolant is when the machine and tools are pushed for maximum production and the heat of working metal causes problems with dimension control and shortens the life of the cutting tools. The gush of coolant carries away heat from the point of operation.

The best all-around coolant doesn't exist but a few modern water base coolant come close. They are either expensive and/or messy. Even the best affordable water based coolants grow mysterious Area 51 grade organisms if left unattended in the sump for more than a month.

If you absolutely positively have to have flood coolant I would suggest oil as you already concluded. What kind of pil depends on the materials you work. I suggest an unsulpherized mineral lard cutting oil. It works very well, moderately messy. non-toxic even when smoking hot, low in cost, works well as a lubricant, prevents rust, etc. It's not much different from a medium hydraulic oil in appearance and viscosity. All trhe industrial supply houses have versions under differet labels. The actual difference between brads is small but of course there is hype. I suggest MobilMet 404 but Houghten, Rustlick, Shell, and a dozen others sell similar stuff for about $15 a gallon.

You might also consider peanut oil. One of the best kept secrets is vegetable and animal oils and fats make good metalworking fluids. I used bacon grease for years cutting threads in gummy steels and aluminum. All vegetable oils pose a spontaneous combustion hazard and that hazard depends on the source of the oil and how it was processed. Peanut oil and corn oil from the bulk containers is a food whereas boiled linseed oil is processed as a drying oil for paint and coatings. One poses a mild hazard and the other dire if absorbed in rags and left loosely fluffed in an open container.

All things considered if you didn't wish to purchase a proprietory mineral lard cutting oil I suggest you subsstitute a medium hydraulic oil. There's little difference in percormance as a cutting fluid between Mobil DTE 24 and MobilMet 404 and the price is about the same. Hydraulic oil is available at any farm store, heavy equipment or hydraulics supply house, or petroleum bulk plant (fetch your own container) found even in small communities. Mineral lard oil has to come from an industrial supply house usually at the other end of a shipping route..

I've heard about using hydraulic oil as a cutting fluid from several other folks as well. But doesn't this stuff strip off paint? I'm imagining something like brake fluid.

Hmm, well if I was going with hydraulic oil I wonder how much different it would be to the spindle oil I'm using? I need to buy 20l of Mobil Vactra oil heavy (or equivalent). I'm told it's not that dissimilar to some of the heavier hydraulic oils. Even with 4 machines, 20l will still last me forever as spindle oil so would it serve as a suitable cutting oil at a pinch? Maybe not quite as good, but cutting down the number of different oils/way lubes will definitely help costs.

Pete

B2F, sorry if I highjacked your thread, but hopefully some of this information will also be of interest to you.

Pete, anything that sheds a little light on this is all good. I use the Mobil Vactra medium spindle oil in my machines, and I do change it occasionally. It always seemed a little wasteful to toss the old oil since it came out looking pretty clean, and now you have me wondering if it makes sense to just save it and use it as cutting oil.

I think I can safely say you won't like running flood straight oil on a manual machine

It gets everywhere including on you! and the smell does not go away.

You think cleaning up a coolantt spill or sprays messy, oil is 100 x worse.

I suggest finding a straight forward ordinary (not semi or full synthetic) soluble oil, and stick with that.

Both these machines have pumps and plumbing installed ready to go, so it seems a bit silly not to use them. On the lathe I mainly manually apply cutting oil when parting and when thread cutting, both are relatively slow rpm so I'm hoping that would contain the oil a little. However yes I can certainly see the carnage that may ensue once the oil meets a small milling cutter revolving at high rpm! The pumps obviously have an off switch so there's no need to have it running.

The reason I'm against soluble is because at the end of the day it's mainly water. Good for the wallet, but I hate the idea of running it on machines that see sporadic use. For the same reason of growing a collection of bizarre scientific experiments in the tanks.

If I'm able to experiment with oil I already have that would be a good start. If it all turns to crap I figure I can always run it through an oil filter and it can go back on the shelf as spindle oil.

Pete

If it's light use, why not look at the low dose mister type coolant rigs available.???

Plus many many parts made in neatt oil have to go through a proper wash process???

borne2fly said:

After hearing and seeing what water soluble coolants can do to machines

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Any metalworking coolant whether it is oil, soluable oil, semi-synthetic, or a full synthetic takes some sort of maintenance. Even oil will go rancid in a sump. Oil has the most dermatitis problems.

I use the Mobil Vactra medium spindle oil in my machines

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No such thing. Vactra is way lube. Now, your machine manual may call for Vactra as a spindle lube, we have several VTLs that use that.

We've got 2 machines that run oil, both are hones and if we could find another product that would work on high nickal and chrome materials, we'd change. We've got half a dozen grinders that run semi-synthetics for about the same reason. The other 100 machines have full synthetic coolant. We have a coolant maintenance program and don't have any problems with the machines or dermatitis.
JR