What coolant do you like and why?

[Len Hoffman]

Pulling this thread out of the past. I found it doing a coolant of choice search.
I'm ready bring a Milltronics RW-15 VMC on line in our shop. This is our first cnc machine and we're trying to make the right choice for coolant.
Considerations of importance to us:
-Good for Milling, drilling & tapping Al 6061 and Al automotive castings, which often have some amount of silicon. Finish is important.
-The machine will almost certainly have periods of in-activity that could be more than week or two in duration. Don't want to have to do any time consuming maintenance, but wouldn't mind running an aquarium air pump if need be. And I will be fitting a belt skimmer to the tank.
-Nothing stinky or strong perfumy I have allergies
-Not harsh to skin. One of the guys has very chem sensitive skin.

Castrol 6754. Anyone here have an opinion?
Trim E206? It has some folks here that like it. The price is reasonable. Do those of you using it find it hard on skin, I like that tramp oil floats to the surface. Smell?

Thanks!

Figured I'd revive this thread with an updated coolant inquiry based on my negative physical reaction to the RustLick Powerchip 2000 that I've been using for the past 7 months. It was hard for me to put my finger on what was going on till this week. I noticed when we put it in the machine the perfumed scent. I found it mildly irritating to my upper respiratory system and skin. Didn't think a whole lot about it at the time. Seemed to perform well, and we don't run the machine a lot so I was pleased that it didn't turn rancid. A couple of months ago I lost my sense of smell, then it was replaced by a strong chemical sensation to any odor regardless of the source. This then migrated to my sense of taste. I am an otherwise healthy person with no underlying issues that would explain it according to my Dr.

I started to suspect the rustlick this week and after using the machine for 8 hours yesterday I went home with a head ache and the taste and scent symptoms went through the roof (after subsiding some over the past 2 weeks of not using the machine)
Has anyone else experienced sensitivities, even of a different sort with any coolant, not just rustlick? If so, have you found a coolant that is effective on aluminum, (which is all we run), and sits well with your particular physical sensitivities?

Pretty pissed at myself for not investigating the msds on the rustlick. It has some pretty strong health warnings. The sheet specifically states that the product should be used outdoors or in a well ventilated area so obviously it has some powerful vapors. Our shop is heated and cooled and has 23' high ceilings for a good work environment. It's not an open air shop so we need something that will work in this type of environment without creating health issues.
here's a link to the powerchip msds for anyone interested. http://metalworking-lubricants.accul...erchip2000.pdf

[RCaffin]

I have said it several times already, but I will repeat it.
You do not need flood coolant on aluminium - ever.
You will benefit greatly from clearing the chips away to prevent any second cuts, and you will benefit from a light misting preventing any built up edge risks.
Read up about MQL: minimum quantity lubricant. As used by major aerospace firms, with big cost savings.

Cheers
Roger

[Len Hoffman]

I have said it several times already, but I will repeat it.
You do not need flood coolant on aluminium - ever.
You will benefit greatly from clearing the chips away to prevent any second cuts, and you will benefit from a light misting preventing any built up edge risks.
Read up about MQL: minimum quantity lubricant. As used by major aerospace firms, with big cost savings.

Cheers
Roger

Thanks for responding Roger. I'm really distressed about this. We do a good bit of hard tapping so some cutting fluid is going to be a must and it's not practical to do that manually. I'm open to the air/mist approach, but my concerns are with tapping quality and the chemical choice is going to be just as critical from a health stand point as a flood coolant. I know a high output shop that switched entirely to mist and you can see haze over the machines. Any ideas on a safe chem?
Thanks!

[RCaffin]

Hi Len

My machine does not do hard tapping, so I have to use a single point thread mill instead. This means my suggestions lack direct experience. treat with caution.

First of all, you do not need continuous mist. Continuous air blast, yes, to clear the chips. that is very important. If they have a haze over their machines, they don't know what they are doing. A pulsed mist is quite enough to keep the cutter surface 'wet'. I might do a 1 second pulse every 15 - 30 seconds. Less on Fortal, more on 5005 - which is horrible stuff.

I use cheap supermarket olive oil, but I know others have used other edible vegetable oils. If the oil is edible, it is going to be 'fairly safe' and won't create allergies or skin problems. I dilute the oil to 25% with kero. Because it is pulsed very briefly, and from a very fine nozzle, there is no haze and the parts stay pretty much dry. The mist is at such a low concentration I usually cannot even smell the kero. Of course, a simple extraction fan is always a good idea to refresh the air in your workshop. You do not need OSHA approval for that.

I create the mist using the air blast. The tiny liquid nozzle is inside the air nozzle. You can buy the whole system from someone like Unist, but I made mine with some LineLoc hose and very fine PE tubing and a bit of (horse-sized) hypodermic tubing. No precision engineering there. You can valve the liquid from a good distance back up the line: you don't have to valve it at the nozzle. (That IS from experience.)

For hard tapping you could just pulse the mist very frequently. If your machine can handle it, you could also do a multiple peck tapping. With a focused air blast this would keep the tap clean and 'wet'. Mind you, if the threads are of a decent size, you could look seriously at doing the threading with a single point cutter to get a really good finish. I tap down to M3 this way regularly, but I think you can get thrread mills for M2 and even M1. The small sizes start to get expensive though! A single point thread mill does not jam.

Check out Understanding MQL : Modern Machine Shop and Minimum Quantity Lubrication - MQL - Metal Cutting Fluids | UNIST .

You will find some extremely complex MQL systems on the market, with all sorts of dials and gauges and whatever. They are NOT needed! ('Complex' => $$$) A LineLoc hose and a feed from an open jam-jar of kero/oil mix with a small Festo valve to pulse the liquid is all I need. The hardware can be very simple.

Cheers
Roger

[extanker59]

Maybe a mist collector would help (after getting rid of that coolant and switching to something else)?

We use Castrol Syntilo 9954. It doesn't bother the few we have in the shop but everyone is different. It also doesn't go rancid. Not a huge fan of it for tapping. Works on titanium, 17-4, and 465 ss (that's our main materials). Flood. Some aluminum for fixtures.

[dharmic]

Interesting that the Datrons allegedly run an ethanol in water mist to cool, blast and wet with zero residue.

Down side is how fast I'd run through coolant, particularly on Friday afternoons. and Monday mornings...

[RCaffin]

ethanol in water mist to cool, blast and wet with zero residue.

It does all that, but you WILL need an extractor fan!
(hic)

Cheers
Roger

[dharmic]

Gotta give kudos to a manufacturer, though, that gives its customers an excuse to claim two crates of vodka a week as an expense on the tax return!!

[popspipes]

I am a hobby machinist and dont use the machine regularly. I use ULSD diesel fuel and oil mixture, doesnt stink too bad , drilling, tapping is a breeze, finishes are very good, and most importantly to me, no rust or corrosion under the vise or on the table............

[RCaffin]

Diesel is just heavy kero. Commercial diesel has some additives which might be less good though.

Yeah - no water => no rust!

cheers
Roger

[popspipes]

Diesel is just heavy kero. Commercial diesel has some additives which might be less good though.

Yeah - no water => no rust!

cheers
Roger

I am new to CNC machining, and probably look at it with a bit different slant on things. I have read thread after thread about the problems related to coolants, after evaporation and sludge/skim on the top of the coolant in the resivoir and the rust under the vise and table staining it wasnt very appealing to me.

To me using a water based coolant is kind of like dealing with a super temperamental sports car.

Diesel just works and the ULSD doesnt stink too bad either, there are a couple problems with it though, it does atomize with cutters over .250, the other is the heat isnt drawn off as well as with water based.
It does evaporate off the table if let set a couple days, so I put a bit of oil in it, probably not necessary, but a bit of peace of mind......

I have used Ridgid cutting oil mixed with kero/stoddard solvent for over 30 years in the lathe sump (stainless work), some smoke at times but really no other problems other than ruined Tee shirts from oil spatters ha!

This is just how I do it, I am not recommending it for anyone else.............