Coolant questions

What dictates to you or your shop when the coolant needs changed in your machines?
How long does your coolant last before you change it?
I was told that if you run different types of material (aluminum and stainless) that it will make your coolant go bad. I don't believe this but... is it true?

I don't think there is any truth in the different materials affecting coolant. I run cast iron, cast alum, cast stainless, 1018 crs, 4140, 303,316,416 ss, 6061 alum, 2024 alum, and alloy 145 copper all on the same coolant. The only one that is hard on my coolant is the cast iron, because of the fuine dust it makes and fills up your coolant tank. It still does nothing to the coolant just fills the bottom of mt tank with fine powderery mess.

Side note when the coolant sets in the cooper chips for a long time it does turn green.

As far as when to change it, it all depends on what work you do how dirty it gets. Do you have an oil skimmer? They help alot with extending coolant life. I find with the amount of coolant lose during running parts the only time I really change it is to clean the cast iron out of the bottom.

Coolant needs changing when it fails to perform it's intended purpose. This can be caused by several things such as too much tramp oils or other contaminants. High bacteria is another issue that can be a health risk. How long coolant last depends on a lot of factors such as type of material being machined, maintained concentration, filtered/skimmed or not, etc.

I have tried many types and brands over the years and prefer a semi synthetic. It has it's down sides too such as causing paint in the machine to peel/bubble at a fast rate. There are material specific coolants out there but most are general purpose and I have never seen a coolant "go bad" from running a certain type of material. If you are cutting material that likes to powder when cut, like cast iron, you will want to have some kind of filter. At the least on any machine you want some type of skimmer to remove way oil.

I have seen properly maintained coolant last as long as a year and ignored coolant last only a few weeks. A little common sense and maintenance will allow you to get the full benefits and your moneys worth out of whatever you decide to use.

If it starts to smell it's time to change it, althought you can buy tablets to put in it to kill the bacterier that grows on the surface. You usually get problems if the machine has been left idle for a few days, if it does smell run it for a while, it usually cures it until you leave it idle again.
Prevention is to keep the recommended consistancy between the water and the soluble oil. obviously water evaporates at an alarming rate so this consistancy is always changing, I usually top up 3 times just water and 1 time soluble mix, but we have refractometer to check it if we feel it is wrong.
Different materials should not affect the coolant execpt colouring but particulates from these materials can do nasty things when it is left idle, especially cast iron as it rust quickly.
Many of the newer soluble oils are better, these have a high concentration of silicon, it stays clean and comes in nice colours and I found it much better for my skin, but it won't mix with the older white stuff.

racen857 said:

I don't think there is any truth in the different materials affecting coolant. I run cast iron, cast alum, cast stainless, 1018 crs, 4140, 303,316,416 ss, 6061 alum, 2024 alum, and alloy 145 copper all on the same coolant. The only one that is hard on my coolant is the cast iron, because of the fuine dust it makes and fills up your coolant tank. It still does nothing to the coolant just fills the bottom of mt tank with fine powderery mess.

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I don't agree, I cut all of those as well besides cast aluminum. Some materials cause more foaming tendacy.

Foaming is caused by not enough soluble oil in the mix.

One shop I worked at used to use those air pumps you can buy for fish tanks to keep the coolant moving over the weekend etc. I am not sure it helped, but the guy running the shop thought so.

UK Graham said:

Foaming is caused by not enough soluble oil in the mix.

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That isn't correct.

Interesting LYK31337, I am pleased you don't agree as it happens a lot on one of my machines, but perhaps you can correct me then.

My personal experience is it "can be" cured by upping the soluble oil levels and is usually a problem on the high pressure coolant pumps, but I am happy for you to correct me.

The cause of foaming is still a mystery to me. I've had techs tell me several different reasons for it but have treated them all and still have had foam issues. Although it is rare, it is a big annoyance when it occurs. Concentration in my experience seems to not play a part.

Still waiting for the answer from LYK31337 but when it happens to me I put about a pint of neat soluble oil in the machine and within minutes it is cured.

Busted Knuckle said:

The cause of foaming is still a mystery to me. I've had techs tell me several different reasons for it but have treated them all and still have had foam issues. Although it is rare, it is a big annoyance when it occurs. Concentration in my experience seems to not play a part.

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This is the same I've heard, they blame it on everything but the product.. My "cure" was to get a bucket of anti foam, drill a very small hole let leak in for about 2-3 minutes every 4 hours of operation, untill bucket us empty. Haven't seen it since but I also haven't ran Cobalt chrome which I did when the foam seemed to start.

UK Graham said:

Still waiting for the answer from LYK31337 but when it happens to me I put about a pint of neat soluble oil in the machine and within minutes it is cured.

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Congratulations

"Still waiting for the answer from LYK31337 but whe..."

...I love these little spats!

I've suspected, when machining aluminum castings (mostly) where foam occurs, when there was none before...To, maybe, attributed to the mold release used... Never been able to prove this though.

Steve

Do I detect an element of sarcasm there Mr LYK31337???

The fact is we have both come up with a solution to the problem of foaming but your comment earlier was "it isn't true" so I expected you to come up with a diffinitive answer, which is not the case, the anti-foaming solutions are a possible temporary cure to foaming but that still does not explain the cause of it in the first place, At least I came up with high pressure and soluble oil levels, so that 1-0 to me then!

Happy days. from the Uk Mr LYK31337

UK Graham said:

Do I detect an element of sarcasm there Mr LYK31337???

The fact is we have both come up with a solution to the problem of foaming but your comment earlier was "it isn't true" so I expected you to come up with a diffinitive answer, which is not the case, the anti-foaming solutions are a possible temporary cure to foaming but that still does not explain the cause of it in the first place, At least I came up with high pressure and soluble oil levels, so that 1-0 to me then!

Happy days. from the Uk Mr LYK31337

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The cause could be many things but low concentration doesn't make sense to me, that seems to me like saying your dishwasher is making too much bubbles, so add more soap.

I'm not trying to argue but it makes no sense, unless you are adding different coolant to it than you normally do.

Foam in coolant is composed of lots of tiny air bubbles, typically caused by aeration. Aeration can be caused by high pressure pumps, leaks in coolant piping drawing in air, or low coolant levels or clogged inlet screens causing the pump to draw in air.

Usually one of the additives in coolant is a defoamer, which would explain why UK Graham has success eliminating foam by adding raw coolant.

I sometimes use a defoaming additive from Blaser. I was told by our Blaser rep that their defoamer contains a molecule that has a pointy shape and it mechanically pops the tiny air bubbles. Over time the defoamer is used up and more must be added. When I have to add defoamer it's a very small ammount, usually an ounce or two. IIRC I'm still on my original 1 gal bottle.

Water hardness also plays a part, the minerals act like defoamer and pop the tiny bubbles. Water that has no dissolved solids will foam much easier than hard water. I use DI water in our coolant and have experienced this first hand.

Hello Gentlemen,

If I may be so bold as to add to the conversation?

Typically high coolant concentration leads to higher foam potential, as well as air being entrained into the coolant by pumps, high pressure coolant systems as well as the cascading action of coolant hitting a flat surface within the machine cabinet. Air can also be entrained into the coolant by leaks in the coolant lines as well as pumps with bad seals. Once foam is established, (especially micro-foam which has the consistency of shaving cream), the problem continues to get worse as the pumps are now not moving a solid fluid, but an aerated fluid which causes the pumps to cavitate, creating even more foam. Higher coolant temperatures will also increase the fluids ability to foam. Using anti-foams helps, as well as calcium additions to the coolant sump. Adding a thin straight oil also will help break the surface tension of the air bubbles, thus acting like an anti-foam. Some coolants will foam more initially when new, due to the emulsifier being very active during the first 24-48 hours, but will calm down once the fluid gets a little dirt load in it.

Dissimilar metals can cause the conductivity of the coolant to rise, thus creating a battery effect in the fluid itself. This can lead to galvanic corrosion if it becomes elevated to a high enough degree. There are metals which will cause the fluid to go bad, such as magnesium, tungsten and zinc. These metals attack the emulsifier in the coolant causing the coolant to split back into its separate components. Once this happens, it's real hard to put things back together again.

Hope this helps!

Best regards,

Brett Reynolds, CMFS
Sr. Applications Engineer
Blaser Swisslube Inc.

toolsteel said:

One shop I worked at used to use those air pumps you can buy for fish tanks to keep the coolant moving over the weekend etc. I am not sure it helped, but the guy running the shop thought so.

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I attended a short seminar on coolants a while back. Bacteria grows the best when that coolant is sitting idle, so the air pumps would help a bit. Another tip they gave us, was to keep the coolant topped off over night. A tank that's low on coolant is more likely to grow bacteria also.

I understand that some coolants have an antifoaming agent within the oil but needs a tad of hard water to release the agent. I have experienced a lot of foaming issues as I only use R.O. water for the tank makeup. Since I've added a small amount of hard water to the tanks along with the coolant and R.O. water my foaming issues have nearly gone away.

My experience with foaming was too high of a concentration from older coolant having evaporated and I tried adding a slightly richer mix. The richer mix quickly caused the foaming issue.
The foaming stopped when I added a 1/2 concentration mix to the tank. So I would have to agree with Blaser but my experience is only personal with just two machines that did the same thing and both stopped when I reduced the concentration levels.
I do not have a refractometer and would like to find out where to get one?

I would also like to know if anyone has ever added any type of chemical to improve the smell? I have a new CNC that had a really bad sump and even after cleaning and flushing several times it still has a residual bad smell. I don't think it had been cleaned in 15 years.
I would rather smell Chanel #5 than old coolant stink. Maybe I will have to do some testing with my small hand spray bottles that I use on the drill.

Michael