# coolant and small cnc mills



## j ferguson (Jul 7, 2014)

Is anyone using a coolant system with their small CNC Mill?  I ask because I'm trying to make sure I've thought about as much as possible before buying and assembling my shop.  Put another way, has any of you had problems with heat build-up in long CNC cycles?  I suppose it would be possible to add rest cycles to the code so that tool could cool off a bit before continuing the work?  

??

Now that I posted this question, I see that some of the issues have been well covered earlier, but I'd still like to know if many of you are running long cycles dry?  cutting aluminum?  steel?


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## Rick Leslie (Jul 7, 2014)

I've been planning a flood coolant system for my Sherline conversion for some time now. (One day I'll actually get around to it.) 
http://www.weaponsguild.com/forum/index.php?topic=37770.0

Cooling is one consideration, but chip removal is another. My main goal was to wash away the swarf. I've also got some cheap home/limit switches installed, so that's a big concern as well. I don't think they take well to being flooded.

I'm interested to see what you come up with.


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## Ray C (Jul 7, 2014)

I realize you're seeking a flood-coolant system and I hope you don't mind me bringing-up mist systems.

I don't use flood coolant but rather, mist coolant.  The parts and bits can range anywhere from quite cold to no more than approximately 100F depending on material and cutting conditions. 

I once used flood systems -mainly with manual machining and discovered that the typical "trickle-flow" coolant does not clear away chips very effectively.  The amount of splatter and run-off was considerable for my setup.  I was not pleased with having a wet floor and found that cleaning-up wet chips/swarf is much harder than just vacuuming/sweeping it up.  My guess is that if you build a fairly splash-resistant enclosure and if you can run your liquid coolant at much higher pressures (say 25 about PSI) the swarf will get washed away fairly well.  If you look at the high-end CNC machines (with totally sealed enclosures) coolant pressures are usually in the 100 PSI range and there are several nozzles aimed at the system components just for the purpose of washing chips/swarf down into the conveyor area and out to a collection bin.  -Probably a bit more extravagant than what you're after...

My method with mist coolant does a pretty effective job at keeping the swarf out of the cut area and it's a highly effective cooling mechanism.  Depending on how much chips are being produced, I sometimes take the shop vac and suck-up the accumulating piles while the part is cutting.  I installed a curtain around the table and it keeps the vast majority of the chips on the table.  The air pressure for a mist system is very low and it's only enough to blow the chips about 3-4" away from the cut.  -No worries about blowing fine particles into critical areas of the machine (or your eyes).

Ray


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## echesak (Jul 7, 2014)

I'm at the 101 level on coolant, but have been doing a lot of research on the topic.  It seems that the paint on the Tormach base and chip tray is not as tough as the paint on the machine itself.  This doesn't appear to be limited to Tormach, as I've seen similar threads for other machines also.  The coolant tends to soften the paint.  I've done a lot of research on the topic and will try some of the coolants that were mentioned specifically or being easy on the paint.  On my particular machine, the paint is perfect, but the chip trays are bubbling and peeling.

Again, this info is coming only from what I've read, but some folks experience issues with mist coolant causing lung & eye irritation and also coating things in the shop.  I have no experience with it, but just thought I'd mention it as a possible discussion point.

Eric


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## chips&more (Jul 7, 2014)

And I have a questions about the coolant and its freshness or useful life cycle? And how do you control the rancid smells that can be found from bad coolant? Is having a coolant system a housekeeping nightmare? Is a coolant system really necessary for the home shop machinist?


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## Ray C (Jul 7, 2014)

echesak said:


> I'm at the 101 level on coolant, but have been doing a lot of research on the topic.  It seems that the paint on the Tormach base and chip tray is not as tough as the paint on the machine itself.  This doesn't appear to be limited to Tormach, as I've seen similar threads for other machines also.  The coolant tends to soften the paint.  I've done a lot of research on the topic and will try some of the coolants that were mentioned specifically or being easy on the paint.  On my particular machine, the paint is perfect, but the chip trays are bubbling and peeling.
> 
> Again, this info is coming only from what I've read, but some folks experience issues with mist coolant causing lung & eye irritation and also coating things in the shop.  I have no experience with it, but just thought I'd mention it as a possible discussion point.
> 
> Eric



Just to let you know, I read a good deal about the lung/eye irritant issues before trying mist.  You should do your own reading of course but, I decided it was a vast improvement over the alternatives.

Some of the issues I discovered are:

1) Some people were running traditional coolants in their mist systems -and this NOT what should be done.  They were indeed getting eye/lung problems from misusing a product.  Mist coolants are different than traditional liquid coolants -although they are the same green/blue color.

2)  The ingredients in KoolMist (for example) are a synthetic version of citric acid (used as a preservative) and an extremely small percentage of a synthetic lubricant.  I used to apply cutting oils on my work pieces and there is NO doubt in my mind, the smoke and skin contamination from that is 1000% worse than proper kool-mist.  1oz of stock kool mist makes about 1 quart of working solution.  The dilution is extremely high and physical contact is very low.  All of my sinus related problems from breathing smoke burn-off have gone away since switching to mist.  Because the vast majority of mist evaporates on-contact with the part, the amount exposed to your skin is trivial.

3)  Several hours of continuous kool-misting uses-up about 2-3 ounces of working solution.  As far as raising the humidity of the working area... I sweat way more than that and suspect bodily perspiration is probably 2-3 times more likely to raise the environment humidity.  The morning blast of humidity from puddles of wet coolant was far worse.


I'm just passing my own experiences and everyone should do their own homework...  Personally though, I wouldn't switch back to wet or oil for all the money in the world.

As with ALL coolants, at the end of the day, you need to wipe-down with an oil rag and give a spritz of light oil (WD-40 etc) to prevent staining or surface rust.  After all, these solutions are 99.9+% water.

I wasn't aware that coolants could soften paint.  I have had no sign of this but, I just don't give a darn what a machine looks like, as long as it cuts...  -Again, my personal preference...

Ray

EDIT:  Fixed a broken sentence.  Clarified wipe-down at end of day.


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## DMS (Jul 7, 2014)

There was an article in Digital Machinist last year by Bob Warfield (of CNCCookbook/GWizard). The topic was coolant, and he went through in detail how the least important part of coolant is actually cooling. Far more important are chip evacuation and lubrication. Chip evacuation is especially important for slotting or pocketing. Lubrication is critical for aluminum to avoid the "OH S*&T" moment when you first experience chip welding. Cooling helps, especially in softer materials or with stainless and titanium. 

I have a "fogbuster" clone that I built. It is fantastic for aluminum and plastic. The only thing I don't like is the noise of the compressor. It makes almost no mess, does not aerosolize coolant, and uses very little coolant. Most of the parts that come off the machine are cold, even after heavy cutting. 

I am running a converted 9x42 knee mill, but the unit I made is small, and would work well on even the smallest machine.


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## echesak (Jul 7, 2014)

Man, this is a very timely thread.  
I'll definitely do a little more research, as I'm not looking forward to having the mess and hassle of flood coolant.  I'd prefer not to have to run the compressor, while machining, but it might be better than having to deal with the flood coolant.  Wipe-down is definitely a good tip.  My machine has a few spots of thin rust / discoloration on the side of the table.  

Eric


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## Ray C (Jul 7, 2014)

echesak said:


> Man, this is a very timely thread.
> I'll definitely do a little more research, as I'm not looking forward to having the mess and hassle of flood coolant.  I'd prefer not to have to run the compressor, while machining, but it might be better than having to deal with the flood coolant.  Wipe-down is definitely a good tip.  My machine has a few spots of thin rust / discoloration on the side of the table.
> 
> Eric



Eric / All,

Kool Mist does not use a lot of air.  You won't need a high CMF rate.  The line that supplies air to the kool-mist units is regulated down to 30 or 35 PSI and the nozzle opening is adjusted to let out just a pin-hole's worth of air.  I have a 45 gallon compressor (located outside in a shed) and it only goes on once every 10-15 minutes.  Also, I place the storage bottle at a level just slightly below the discharge nozzle.  This way, you won't need a lot of air to draw the solution all the way from floor level.  

Last month, Enco had the units on sale for 88 bucks and Zoro tools usually has good prices on them too.  The little magnetic base is OK but on the mills, I use zip ties to fix them into location otherwise, they'll vibrate off position.  I have two on the CNC mill, one on the lathe, one on the surface grinder and one on the manual mill.  -Never had a problem.  I use the KoolMist 77 solution.  They have one other solution but the #77 is more versatile.


Ray


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## j ferguson (Jul 7, 2014)

Keep it up guys, this is wonderful.  I'm reminded once more how little I know about things.

You were right, I was thinking of flood coolant and now I can see that misting can solve my problem.



Thanks to you all.

john


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## DMS (Jul 7, 2014)

I run my mistless at about 20psi, but I have a small (5gal) compressor. It switches on every few minutes. It's also not the quietest of compressors. With the spindle going, and the hiss of the mistless, and the compressor... things can get a bit loud. I have plans to build a dedicated (quite) compressor for the mist setup, but it's still in the backlog.


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## 09kevin (Jul 8, 2014)

It seems that the paint on the Tormach base and chip tray is not as tough as the paint on the machine itself.  This doesn't appear to be limited to Tormach, as I've seen similar threads for other machines also.  The coolant tends to soften the paint.  I've done a lot of research on the topic and will try some of the coolants that were mentioned specifically or being easy on the paint.  On my particular machine, the paint is perfect, but the chip trays are bubbling and peeling.

Eric[/QUOTE]

I thought I read that Tormach fixed the paint issues on the series 3 machines?  I didn't have any problems with my paint using the coolant Tormach sold, but when I switched to Tech Cool 5052 the paint started to bubble.  

I prefer flood coolant for lubricating and flushing chips out, I let the chips sit overnight so the coolant runs off then use a shop vac to clean up. I did modify the Tormach enclosure to help keep the coolant and chips inside because it will make a mess really fast :whistle:


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## echesak (Jul 8, 2014)

I had heard the same thing about the Tormach paint.  But like I said, the paint on the machine is perfect.  It's the chip tray that's peeling.  So if they changed the paint on the chip tray, it's probably on a later unit of the base/chip tray than what I received.  I removed and repainted the chip area on the base.  But I doubt that it will hold-up to much heavy coolant use.

Like J Ferguson, I'm looking for alternatives.  For me it will probably come down to money (spent my CNC wad).  I have the flood coolant system and would have to buy/build a droplet system.  I'll probably try flood first, since that is what I have.  I read about a couple coolants that perform well.  I know nothing about them, but the ones I was reviewing were TRIM E206 and Hangsterfers S-506 CF  and Rustlick WS-5050.  Other forum posts have indicated that these work well, are easy on the paint, have a low odor and don't seem to get rancid (the top 4 on my list).  Enco has the Trim coolant and free shipping over $50 currently.  So That's probably what I'll try first.


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## j ferguson (Jul 10, 2014)

I'm leaning toward flood system.  Shop will be in garage.  Landlord requires that car be parkable at any time because of deal they (well, the developer) made with local zoning.  This means shop is workbenches and tool chests arrayed at end away from car-door and on one side.  No ventilation except by gravity with big door open.  Rack storage system on other wall with usual family treasures in bankers' boxes.  

So the concern is eventual film of coolant residue on everything.  And I suspect it would happen quicker with a misting system.

Obviously, I could buy some ducting and build an extractor (5 1/4 inch muffin fan) to convey the vagrant mist from the mill to the outdoors - cheap and likely effective and maybe I should just do it.  Residue film everywhere seems equally likely if I just brush on cutting oil like I did 55 years ago in the wonderful shop where I worked and should have learned all of this stuff.  

O/T but ... The place was set up in 1914 north of Chicago, mostly ran on a single motor with overhead shafting, leather belts, etc.  Newest machine (only one with coolant system) was horizontal band saw.  Second newest were War Production Board South Bend, some Hardinges,. and a Delta Drill.  Everything else had been there in 1918.  

Unfortunately (well fortunately for me) I'm the only one who worked there in 1960 who is still alive so I can't find out what we used for cutting oil.  The smell is imprinted on me somewhere, but I haven't run into it in years - probably suppressed by EPA.  But its use did lead to film on windows - whose cleaning annually was one of my jobs. Might also have been Pipe tobacco fumes -- Oscar Trumbull Scalbom.  So it sounds like an exhaust duct will be part of the scheme.  I really don't want to have to clean the walls.

BTW, if you think anything I write is nuts, I won't take offense.  I spent most of my career doing things I didn't understand and am used to criticism.  In fact if I don't get any, it really bothers me.


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## Ray C (Jul 10, 2014)

j ferguson said:


> I'm leaning toward flood system.  Shop will be in garage.  Landlord requires that car be parkable at any time because of deal they (well, the developer) made with local zoning.  This means shop is workbenches and tool chests arrayed at end away from car-door and on one side.  No ventilation except by gravity with big door open.  Rack storage system on other wall with usual family treasures in bankers' boxes.
> 
> So the concern is eventual film of coolant residue on everything.  And I suspect it would happen quicker with a misting system.
> 
> ...



FWIW, In my experiences, I cannot relate to the concept of a film of residue from mist cooling.  Maybe if I had many machines running with full PSI misters blaring away -all day long... it would increase the humidity level.  Running at lower pressure, my kool mist systems use about 1-3 ounces of liquid stock solution after several hours of continuous operation.  About one ounce of that solution accumulates on the part, vise or table and gets sucked-up by the vacuum cleaner when you clean-up the swarf.

If I had to guess, the shift in humidity after a light rain or morning dew on a temperature transitional day produces 1000 times more moisture leading to eventual dirt, dust and residue development on the walls and ceiling.

-Not meant as a criticism but as a data-point to aid your understanding and perspective on the issue.  ... I have no vested interest in which method you chose... -Just passing along my experiences.


Ray


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## echesak (Jul 10, 2014)

Made me chuckle, out loud.   I worked the Corporate Engineering a few years ago, and didn't understand most of what I was doing, or why I was doing it.  But I must have done it right, as I climbed the ladder in my 13 year career there.

Again, this topic is beat to death, on the web.  But I also read that Carbide end mills, prefer not to be used with flood coolant because of the thermal shock to the material (when machining heavy cuts or harder materials).  So there's probably a place for both in the shop.  I'll probably make a droplet misting unit, as I probably have all the materials in the shop (including a cool 316 stainless tank that was used for Coke syrup).

The car is probably the least of your worries, since it will get a regular wash.  But like you, I'm not interested in having the other machines and everything else covered in coolant residue grime.

Eric


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## Ray C (Jul 10, 2014)

echesak said:


> Made me chuckle, out loud.   I worked the Corporate Engineering a few years ago, and didn't understand most of what I was doing, or why I was doing it.  But I must have done it right, as I climbed the ladder in my 13 year career there.
> 
> Again, this topic is beat to death, on the web.  But I also read that Carbide end mills, prefer not to be used with flood coolant because of the thermal shock to the material (when machining heavy cuts or harder materials).  So there's probably a place for both in the shop.  I'll probably make a droplet misting unit, as I probably have all the materials in the shop (including a cool 316 stainless tank that was used for Coke syrup).
> 
> ...



I personally have never experienced any thermal shock problems with carbide endmills and I use them almost exclusively -and did so with both flood and mist coolant systems on both the lathe and mill.  Things didn't seem to remain very cool with just trickle flow coolant.  Possibly with high pressure coolant and multiple nozzles, it comes close to the cooling effects of mist systems... I don't know.

What I do know from experience is that with mist systems, the part and bits (be it lathe inserts or endmills on a mill) never get above a slightly warm feeling -maybe 100F or so.  Most of the time, the parts remain cold.  This has vastly simplified things as I no longer need to worry about coefficients of expansion offsets when making a final pass on a critical cut.

In the realm of high-speed "hard machining" -usually with very hardened materials or materials like titanium or Inconel that work-harden to extreme amounts, folks use ceramic inserts.  I recently did a project here and used ceramic inserts.  You cannot use any form of coolant with those as they rely on generating heat.  The insert gets glowing orange hot and doesn't start cutting well until it gets that hot.  One drop of coolant on that and it will shatter.  "Hard Machining" is a whole different ballpark and largely out of the hobbyist realm.  It is fraught with safety concerns regarding oil fires and nasty swarf burns that leave immediate 3rd degree burns -small ones but painful nonetheless.


Ray


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## j ferguson (Jul 10, 2014)

Thanks much Ray, I can see i need to think about this some more.


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## DMS (Jul 10, 2014)

The problem with carbide and intermittent cooling comes when you bury the cutter dry and then think "hey, that looks like it's getting hot, I better spray it down". With carbide the the rule is all or nothing, either use coolant constantly, or run it dry. Worst thing you can do it's spritz it periodically.


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## jererp (Jul 10, 2014)

When I started in manufacturing 40 yrs ago, we used only 2 types of coolant. First was a soluble oil, which was 5-7% oil, the balance water. The other was straight oil. Bacteria growth was always a problem in the soluble oil systems, fire a concern for the oil systems, and oil mist in the air a problem for both. Just because it is 'flood coolant' doesn't mean no mist. 

 Synthetics solved a big part of the bacteria problem, but they were a very effective paint stripper for oil based industrial paints. 

I'm not familiar with the current products on the market...just thought I'd share a little history.


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## countryguy (Jul 10, 2014)

I bought a small Mister unit from Production Tool Supply (on the web) and this unit is carried by many other online places.   Came w/ a Qt of fluid as well.     Read  read read is about all I can say w/ something in which health concerns are of importance.     I love my unit.  The air pressure required is very tiny.   And it does a GREAT job.  A few ounces for a 5Gal bucket!  And I have cut a lot of 1045 w/ carbide and this unit w/ no issues thus far.      w/ the smaller CNC mills your removal rate is often pretty small.  So I felt comfortable putting this to good use.    Dry's clean and w/ a little bit of a film that is "lube like" in  feel.   Enjoy CG


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## xalky (Jul 10, 2014)

+1 vote for the kool-mist setup. It's a good cooling setup without all the mess. Set it up like Ray sais and there will be no mist in the breathing environment. 

I wish I could say that for the flood coolant setup I have on my big lathe. Flood coolant also deposits quite a bit of humidity in the air from just sitting there.I use the flood coolant on my big lathe because, it's easier when making heavy cuts, I have splash guards everywhere and some of the coolant thru drill bits I use require it.  But my smaller machines use the koolmist setup with the #77 solution.


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## andyman (Jul 21, 2014)

I'm surprise nobody here recommended or event mentioned MQL cooling.  MQL = minimum quantity lubricant.  If your running a small mill and want to avoid the mess of flood and the problems with mist then MQL is what you want.  

MQL allows you to cut almost dry.  It reduces friction down to a minimum and so the tool bit does not get hot (hours of runtime are only barely warm tool bits).  The chips on the other hand gets hot.  I recommend anyone to watch MQL cooling on you tube.  

The only problem with MQL is cost.  You need a pump and special lubricant (accu-lube LB2000 for example).  But with MQL you get much better performance then mist, you avoid the mess and toxicity of flood, and theres a possibility of faster cut speed because lubricants are not diluted in water like flood  or mist.     You also avoid bacterial or fungus growth.


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