When To Use Coolant

[Bill C.]

If you decide to use flood method be sure to splash guards on your lathe and mill. Most mill table I have used had threaded drain hole(s) to recover the coolant. The lathes I used had chuck shields so coolant wasn't flying up in my face. I have used misters as well, I liked them as well. Be sure to turn off the air when you walk away or you could have a pool of coolant if there is no drain. Some shops used cutting oil while others used soluble cutting fluid. Between the two I preferred the water based ones, easier cleanup and laundry.

 

[JPigg55]

Besides flood coolant and misting, what other methods are used ?
BTW:
WD40 original use was to prevent corrosion and ice build-up from moisture on Atlas rockets.

 

[mikey]

I don't do production runs in my little shop so I can't justify the expense and the mess of a coolant system on the lathe or mill. I brush or dribble cutting fluid on lathe work and brush it on when on the mill. I use a syringe with a blunted needle to get it into a bore or when parting. I use a wax stick lubricant on the bandsaw. Simple, keeps the mess down and I don't deal with rust or sludge from water-based coolants.

I used a lathe once with a coolant system and it worked great! But then I had to clean it afterwards and it took me three times as long to clean up as it took to make the part. I haven't used a mill with coolant but the mess looks even worse. I suppose you have to decide just how much you're willing to do to have it. My parts don't seem to care one way or another.

 

[RJSakowski]

I used a lathe once with a coolant system and it worked great! But then I had to clean it afterwards and it took me three times as long to clean up as it took to make the part. I haven't used a mill with coolant but the mess looks even worse. I suppose you have to decide just how much you're willing to do to have it. My parts don't seem to care one way or another.

+1 on the cleanup issues. I have a flood coolant system on the Tormach and it seems to give a better finish than running dry which is one reason that I use it. For those of us who use the machine infrequently, a thorough cleanup after each use is essential and many times the cleanup will run five times the length of the milling routine. If a mill or lathe is in constant use, immediate cleanup is less of an issue,

A typical cleanup for me consists of removing the bulk of the chips, followed by a wash-down with the coolant to flush the remainder of the chips into the chip basket. I use a length of pvc hose on my coolant nozzle for washdown. Then I will remove any fixtures and use compressed air to "sweep the table, bellows, etc.

Another issue for the occasional user is water loss through evaporation. The coolant level has to be maintained in the reservoir and is usually done by adding water . However, since the coolant concentrate is also diminished during use, it has to be added at times. Maintaining the correct coolant concentration requires some mean of measuring it. I use a Brix refractometer for that task. All of this adds a lot of overhead to the operation.

The bottom line is that, while flood cooling has advantages, many times I just resort to running dry or using an oil based lubricant brushed or sprayed on.

Bob

 

[mikey]

What factors do you use when deciding on using coolant or not and type of coolant ?

Wondering what types of coolants I should be aquiring, when to use, and how I should be using them.

I meant to answer these questions and got caught up in the flood coolant thing.

Other than brass, bronze or cast iron I always use cutting fluid on the lathe or mill. This is not just to lubricate. It also changes the way the chip deforms at the point of cut. The best example of this is when boring. A good cutting fluid can change a chip from long, stringy chips to nicely coiled ones that self-eject from the bore. Cutting fluid also reduces the formation of a built up edge (BUE), especially with Aluminum. Your finish will also be much better with cutting fluid with most materials.

If you use carbide tools it is best to decide on whether or not to use cutting fluid from the beginning. Don't go without it and then shoot a bunch of it on a finish pass - you can cause thermal cracks on the insert. This is especially true when boring.

As to which types of cutting fluids to get, there are as many opinions on this as there are cutting fluids. I'll give you my preferences:

• Aluminum: WD-40 for general work, A-9 for fine finishes or when I need to take a whisper cut and need superior lubrication.
• Steel: Tapmatic #1 Gold. This stuff is readily available and works well. I especially like it for harder materials like 1144, 4140 and tool steels - good finish.
• Stainless: I just use Sulfer-based cutting oil. I hate the smell but I like the finish, especially when threading and knurling.
• Brass, bronze, cast iron: None

Whatever you use, be sure you have good ventilation. Breathing in the smoke from any of these fluids is not good for you. Remember that the chemicals from any fluid may be absorbed through the skin so nitrile gloves are always a good idea. Safety glasses are also important - an eyeful of cutting fluid will teach you the truth of this.

You cannot argue the value of temperature reduction, chip clearance and improved finishes with flood coolant - it will always be better than a brush. You need to decide for yourself if the expense and clean up hassles are worth it for the work you do.