[AMCTony]

I am having an issue with coolant staining parts. The parts are aluminum and the coolant is Castrol Syntilo 9954. It is leaving a yellowish stain on the parts. Has anyone run into this problem before? Any solutions?

[clutzed]

we always use just plain old every day kerosene for aluminium , never had any heat or staining problems

[jetpig1]

Look at the stats:

http://www.castrol.com/liveassets/bp...ntilo_9954.pdf

Says 8.0 - 8.8 ph at 5%. Fairly base. Like seawater. If you are mixing at 5%, no problem I would think. higher concentration means more base, towards the Drano side of the ph scale. You might just try immediate rinse of parts in a tub to lower ph.

[rhrubin]

We had a similar-sounding problem with staining.
The problem only occurred with one machine.
Turned out it had nothing to do with coolant, concentrations, Ph, etc.... but had everything to do with grounding.
The parts were being anodized as they were being machined.
The ground rod for the machine with the this staining problem was in middle of the shop. Here in the desert, the soil had dried to such an extent that the ground rod would not conduct.
We slowly poured a few cups of water alongside the ground rod, allowing it to seep in through the hole in the concrete floor.
Solved our problem.

[ilbebach]

We had stains on the aluminium parts if the coolant was allowed to dry on the parts

We keep a tub of Demineralised water into which the parts are dipped immediately after removing from the machine.

solved the stain problem....
( we use castrol 'COOLEDGE SL ')

[Triv]

Sometimes, it is a combination of factors.
1) Your coolant does not inhibit electrolysis as well as it should... Shop around for a better coolant.
2) You have fines suspended in your coolant from machining other materials. Mixing copper, steel, zinc and aluminum on one machine can create both black and fuzzy white stains.
a) Clean out the sump thoroughly.
b) Install a filtration system. It does not need to be too elaborate, but I would suggest a 2-stage system with both coarse and fine filters.

Good Luck!

Triv

[bglad]

I've been using Hangsterfers NeoSol 300 for a couple years, best stuff I've ever used, not cheap, but quality never is.

[apache405]

We had a similar-sounding problem with staining.
The problem only occurred with one machine.
Turned out it had nothing to do with coolant, concentrations, Ph, etc.... but had everything to do with grounding.
The parts were being anodized as they were being machined.
The ground rod for the machine with the this staining problem was in middle of the shop. Here in the desert, the soil had dried to such an extent that the ground rod would not conduct.
We slowly poured a few cups of water alongside the ground rod, allowing it to seep in through the hole in the concrete floor.
Solved our problem.

That's and interesting, because the grounding system should be totally bonded together-- the neutral and ground lines are both bonded at the service entrance (at least in single phase systems, not 100% sure about the grounding in a three phase set up). That means there might be a larger grounding issue in the whole wiring system of your building.

[AMCTony]

I changed out the coolant and checked the machine ground. Still getting stains. The fixture to hold the part is 1018 steel. Could that be causing the problem? The staining is worst where the part contacts the fixture.

[apache405]

Possibly a reaction due to dissimilar metal junction? Can you warp the contact points in some thing sheet aluminum?

[AMCTony]

Changed to an aluminum fixture. Problem is still there. Ready to find a tall building and jump off. First I think that I will try installing a new ground rod and run new wire. If that does not work then I am totally lost.

[scadvice]

…think of something that is coating the surface. Can you wash it off with soap and water? (A water based stain) Or do you have to use something like alcohol? (A petroleum based stain). If neither, then can you rub it off with #000 steel wool? Or does it take something more aggressive?
Electrolysis whether anode or cathode side will be leaving (depositing) or taking away material (pitting). So, if that is what may have happened, you should be able to see and feel it. Check the stain with microscope, if you can. Also the clamping fixture will also display the same problem.
What kind of Aluminum alloy are you cutting? Is it all the same lot of material?

BTW - The electrolysis marks I have seen are mostly gray.

Steve

[ilbebach]

Please check the ph value of the water you used for the coolant mix...
mjm

[AMCTony]

I do not have a way to check the pH of the water. I am using destilled water but you never know what may have gone past QC. I installed a new ground rod an ran a new ground wire from the machine main casting. I decided to check the wire with a meter before hooking it up to the ground rod. There was 1.2 VDC between the machine and the ground. This leads me to belive that the ground rod that we were using was installed by a cheater i.e. cut short so they did not have to drive it 8 feet in. I will keep the forum posted as to what happens next. The aluminum I used for the fixture is from the same stock that the parts are made of (same bar). The material is 6061-T6. The staining is not uniform on the part and is yellow/brown in color. Water, Soap and water, Acetone, or Kero will not take off the stain. I suspect that the part is annodizing somewhat. The voltage from the machine casting to the ground rod was +1.2 VDC. This would support the annodize theory but that is not a lot of power. The cycle time on the part is around 1 hour so that may be making the issue more obvious than otherwise.

[apache405]

A value for the current from machine to ground would be nice, a few milliamps does not strike me as being enough to cause anodizing to occur, while something like an amp or more would be enough.

Is the fixture stained as well?

BTW an electronic pH meter is a voltmeter with some special probes, but I have heard of a normal voltmeter being used to determine pH, and I tired it, but got kicked out of the lab before I could get it to work.

[rawen2]

A pool or spa supply store should have inexpensive ph testing kits.
Ralph Wenzl

[brianb4FI]

Maybe has nothing to do with it, but when you changed out the coolant did you switch to a different one? The Castrol Syntilo 9954 is rated for ferrous metals - there are other Castrol products that are rated for non-ferrous, or both. It may be the coolant itself that is causing you this problem.

This was posted earlier:

http://www.castrol.com/liveassets/bp...ntilo_9954.pdf

[AMCTony]

I have been running 9954 for 2 years without trouble on aluminum. I just ran parts today with no staining. I did talk to castrol and they said that grounding could be an issue and it may take a few days for the charge in the machine and sump to disipate to ground. At this point I am totally stumped. They did suggest going to Castrol Hysol MB50 semi-synthetic. Anyone use semi synthetics out there? If so would this be worth a shot?

[apache405]

I did talk to castrol and they said that grounding could be an issue and it may take a few days for the charge in the machine and sump to disipate to ground. At this point I am totally stumped.
They did suggest going to Castrol Hysol MB50 semi-synthetic.

Give it a try... The couple of days they ask for is this weekend, although I think the machine would dissipate its charge in a short amount of time.

How old is the building that houses your shop? Also, has any plumbing work been done on the building around the time the problem with staining developed?

[AMCTony]

The building is about 10 years old. The machine has its own seperate ground rod now. No plumbing work has been done as long as I have been here. it has been about 3 days since I gave the machine its own ground so I am going to give it another try. I am going to anodize these parts anyway but if that was not the case then I would be in deep crap right about now.