Coolant Life?

[flyinchips]

I am using the Super 600 coolant Tormach recommends. I have had it in the machine about 15 months. It smells fine, has the same golden appearance as new (possibly a little darker) and I adjust the brix regularly. My guess is there are 80 actual hours of use on it. Does this stuff have a shelf life? Should I be replacing it, because it is more than 12 months old?

Any thoughts?

Cheers

[GLCarlson]

I'm in much the same boat, but using Valcool 700, and have similarly low hours but long storage times on my coolant.

If it doesn't smell, the micro preservative system is intact (there would be other indications if it had failed, too). Since you're watching the concentration (RI), that's staying in range, and I think you'd see a physical change if the microemulsion degraded seriously. I'd kinda like to know that the pH hadn't changed, too (test strip is good enough). About the only worry would be that there might be some hydrolysis or other degradation in the anti-corrosion system. I suspect that you can get 24+ months if you keep an eye on it...but I'd be conservative here.

My rule of thumb is to do just what you are: check everything, adjust as needed, and keep going- until I hit 12 months or so. I've made it a practice to flush and replace every year. I'm pretty sure I'm recycling good coolant. But, given the relative cost of a gallon of coolant concentrate and a new machine, I'm going to stick with 12 months or so as an expiration date on coolant. I won't go nuts if I'm a month late, or early, changing it. And, btw, I write the date of the last change on a hang tag on the tank, and in the machine log.

[bevinp]

What about the way oil, or do you use an oil skimmer?

My coolant is a synthetic one which is a clear green when new but becomes clouded after only a few hours of use. The way oil seems to mix with the coolant and does not float on top (when the coolant is "resting"). So I guess it forms a suspension or colloid. Whatever, there are a few consequences of this mixing.

One good result is that the oil enhances any rust prevention provided by the coolant. In fact, leaving the coolant to dry on surfaces is a good rust preventative action for me.

But the suspended oil does interfere with the Brix readings. I had to add half a tank of water during a session when the pump was exposed. When I Brix-ed it the reading was above that of the coolant when new!! I wish I had measured before adding the water. I now intend to monitor the readings the next time I replace the coolant.

I will take readings before and immediately after a session while the coolant is well mixed. I will also note the level in the coolant tank the morning after a machining session, and take a Brix reading then. I will post the results in a few months.

The other probable effect is that the way oil mixed in the coolant must have an impact on the cutting effectiveness of the tool. And I am concerned that this might be an adverse effect. After all, way oil is designed to stick to surfaces and prevent wear. But I am no expert.

Does any one have any good information on the impact of way oil on tool cutting?

[beanbag]

A good coolant is supposed to reject the way oil and cause it to float on top, but obviously you have to let it rest a bit. I hate it when way oil mixes with coolant because it leave an oily film on parts that doesn't rinse off with water.

[flyinchips]

Changed the coolant. It had, indeed, hydrolyzed. There was a "plastic" film on the top of the coolant. I could lift the "sheet" off the top with my hands. I think I'll adopt GL Carlson's practice of replacing yearly, weather it needs is or not.

To answer some of the other questions: I have a skimming pillow for tramp oil collection. There was maybe 1 ounce of oil on top of the coolant in addition to the sheet of stuff I mentioned. The tank interior was spotless, nary a chip or any grunge in the bottom.

[beanbag]

Could this film be due to dissolved Tormach paint?

[underthetire]

Put a fish tank bubbler in the tank. We go 2-3 years on the same coolant.

[flyinchips]

No, It wasn't Tormach Paint. Wrong color and I still have 99% of my paint.

The bubbler is a good suggestion, however in the spirit of KISS, I'll spend $7.00 to $8.00 on fresh coolant every year in place of the fish pump.

[GLCarlson]

Follow-up. It's hard to find any quantitation about coolant life. Master and Valenite claim 'long'- but are careful not to say how long. I did see several comments on other forums about 2-3 years.

Air bubblers are a mixed blessing: they'll keep the bugs down, but encourage evaporation and can create aerosols. I've also seen suggestions that copper wool (not steel wool- copper) can help (copper is antimicrobial), but I've never tried it. Silver (zero valence silver) is also effective. Unfortunately, modern coinage is neither pure copper nor silver, so don't toss a few pennies in the tank- they're mostly zinc.

Regarding that plastic layer. I had one too, one time only, in my new Tormach tank. I think it's some hard to see piece of shipping material, maybe on the pump shaft or inside top tank cover. I can't see a way the emulsion system or oils are going to polymerize to a plastic sheet with any integrity at all. Found it wrapped around the pump intake, hauled it out, and haven't had that problem again.

[shred]

FWIW I have a bubbler on a timer to cut down the evaporation (which is a lot in my machine, both from use and from sitting). It doesn't need to be run very long every day.

[C*H*U*D]

To answer some of the other questions: I have a skimming pillow for tramp oil collection.

On a similar note, how long are these pillows good for? I got two when I got my 770, and have had one in from the beginning of use. My coolant looks good, and I check the concentration regularly and adjust accordingly, but have been curious as to when I should change the pillow.