Coolant on Mill... why isn't there rust EVERYWHERE?

[Dan_the_Chemist]

I see people using flood coolant or mist coolers on milling machines -- and the machines are not completely coated with rust! I have to fight on a nearly daily basis to keep my machines from corroding into useless mass of rust from condensation and humidity in the air.

How do you guys manage to splash water all over your machines and not end up with this?

[Toolguy]

It all depends on the coolant. I use Hangsterfer's S-555. It's a water soluble something, not oil. If kept at the right concentration, when the water evaporates, it leaves a waxy film that protects a lot like cosmolene. If you get it wet again, it goes back to being coolant. It never has a bad smell. All I've done for 20 years is add water or coolant to get the right mix. You need a 0 - 10 refractometer to check the concentration. That's the same one they use for making maple syrup. I keep my coolant around 7 to 8. You also need to use the compatible Hangsterfer's way lube to keep from contaminating the coolant. A lot of way lubes have sulfur and other chemicals that totally mess up any coolant. I use flood coolant, I don't want to breathe the mist. The mist also gets on everything else in a wide radius. It goes much further than just the part you're working on.

[BCRider]

I use a synthetic cutting coolant/lube. It mixes up to about the color of very weak tea. Or the color of pee from someone with "issues". As in clear but slightly orange.

On exposed surfaces the oil in the water permits it to dry away and only leaves the light oil. But if it sneaks under the vise and sits between the table and vise then over a few days things in there go very brown. I marked my new miles table table in less than one week's ownership from this. My standard practice now is to coat the base of the vise liberally with a thick oil. My way and dovetail oil in fact. This deflects the coolant from getting in there when they are clamped down.

I took to doing the same thing but with a thin smear of water resistant boat trailer grease on the backs of jaw vise jaws on the two milling vises.

[Tobias-B]

They're not using salt water?

t

[reggie_obe]

They're not using salt water?

t

or rat pee.

[JRouche]

I dont know. I have to coat every piece of metal in my shop, it will rust out.

I really dont use a lot of coolant or lube. For a couple machines I do and its oil based, no water. I would rust while filling the coolant tank!! Its that bad here. JR

[Dan_the_Chemist]

I dont know. I have to coat every piece of metal in my shop, it will rust out.

I really dont use a lot of coolant or lube. For a couple machines I do and its oil based, no water. I would rust while filling the coolant tank!! Its that bad here. JR

EXACTLY... I can clean and brighten the Kurt on my mill, and the next day it is already light brown.

[Lew Hartswick]

Dan, As to your problem (not the coolant question) just move to southern part of NM or AZ where the RH (relative humidity) is in the single digits in the summer and you don't even have to oil anything to never see a sign of rust. Been here for nearly 30 yrs and the column of my drill press isn't a bit rusty and have never touched it with a bit of oil . :-)
...lew...

[Doozer]

It is not the water based coolant that remains on the surface
that will cause rust. I see suggestions of wiping down your
machine and vise. All good and fine, but it does not matter.
The problem is when the water based coolant gets into the
dovetail slides and the inverted vee way slides.
I am not a chemist, but I see evidence that the water based
coolant is having some chemical reaction with the way oil
that is used to lubricate the ways. I think over time, there is
some oxidation happening when the two mix, and it makes
some kind of acid, which allows oxygen to rust the iron.
I have had thoughts of.... What if a coolant making company
did some extensive research and analysis to see what happens
when their water/oil coolant type product actually reacts with
iron and way oil over time and different temp and humidity and
light/dark conditions. Maybe they would find that they need to
market a very specific way oil formulation that does not allow
this acid reaction to happen and subsequent iron rot.
It is too bad that big oil, like Mobil or Chevron, or whoever
does not use their research team to develop a machine tool
coolant type of emulsion oil. Who better to make a compatible
chemistry for way oil and coolant soluble oil ? Just an idea.

--Doozer

[Rich Carlstedt]

I was told by a Museum Curator that the critical humidity level for Iron is 56 %- Anything higher is detrimental to ferrous material.
Think of Heinz 57 logo , so if it's 57 or higher , beware !
Not much of a problem here in the far north , except in the wet spring time when I use a dehumidifier in the shop, but if
you are located where you get saltwater breezes, good luck !
Boeshield Time
Rich

[Toolguy]

It is not the water based coolant that remains on the surface
that will cause rust. I see suggestions of wiping down your
machine and vise. All good and fine, but it does not matter.
The problem is when the water based coolant gets into the
dovetail slides and the inverted vee way slides.
I am not a chemist, but I see evidence that the water based
coolant is having some chemical reaction with the way oil
that is used to lubricate the ways. I think over time, there is
some oxidation happening when the two mix, and it makes
some kind of acid, which allows oxygen to rust the iron.
I have had thoughts of.... What if a coolant making company
did some extensive research and analysis to see what happens
when their water/oil coolant type product actually reacts with
iron and way oil over time and different temp and humidity and
light/dark conditions. Maybe they would find that they need to
market a very specific way oil formulation that does not allow
this acid reaction to happen and subsequent iron rot.
It is too bad that big oil, like Mobil or Chevron, or whoever
does not use their research team to develop a machine tool
coolant type of emulsion oil. Who better to make a compatible
chemistry for way oil and coolant soluble oil ? Just an idea.

--Doozer

That's what Hangsterfer's did. They have coolant compatible way oil, or looked at the other way, way oil compatible coolant. Neither one adversely affects the other. I have been using their system for a long time, and don't have any of the problems a lot of others have with different coolant and way oil. The way oil is a total loss type of thing. You can't keep it out of the coolant.

[Doozer]

That's what Hangsterfer's did. They have coolant compatible way oil, or looked at the other way, way oil compatible coolant. Neither one adversely affects the other. I have been using their system for a long time, and don't have any of the problems a lot of others have with different coolant and way oil. The way oil is a total loss type of thing. You can't keep it out of the coolant.

Hey, did not know that.
If their 2 oils work together well,
that is worth promoting.
I am really impressed with this,
if it works like it is supposed to.
Cool.


---D

[old mart]

A few years ago, we took the headstock of of the bed of the 70 year old Smart & Brown model A. Unnecessarily as it turned out just to remove the spindle which is a 15 minute job when you know how. The lathe had been used with water soluble coolant for most of its life and the headstock to bed interface had muck and very little corrosion, more staining, which scraped off easily. I have never tried to use the pumped coolant, but use a 10% mix of some Rocol concentrate in tap water from a squirter bottle. This has never caused any corrosion or smell, probably as my mix is pretty strong.

The machinery in the picture looks like it has been immersed in the sea for about 10 years.