Coolant stains on aluminum

[JpBinc]

Hi All,
I am new to the milling world and have just completed my conversion of a seig x3. I have a flood coolant system on the mill. I am cutting aluminum (5052, 6061) and have a bad problem with the coolant staining the metal. I am using Koolmist formula 78 (which is a mist and flood coolant) can anyone help me with a better coolant for aluminum???
Thanks
JpBinc.

[phantomcow2]

What kind of stain, color and all? I use Kool mist 77 and never had any problems.
At work we use Trim coolants, they leave no stains or anything and work quite well. I know we order them from MSC in 5 gallon buckets

[JpBinc]

The stains seem to be any place the coolant sits for a while. it turns the metal a light brown almost like tarnish on silver looks. In some places it turns white. I have been using mothers aluminum polish and the stains come out but I would like to try a different coolant.... So you have used koolmist formula 77 without getting stains on aluminum..
Thanks
JpBinc

[phantomcow2]

Never have had a stain, and been using this stuff for 9 or so months. I diluted it before 1:32 like it said to, but this seemed to cause rust. Now I dilute it probably 1:20, no longer getting rust. And so stain

[JpBinc]

Thanks for the info.. Did you use tap water or distilled?? I used distilled and I too deluted more than 1:32

[phantomcow2]

I just used tap water. At 1:32, did you ever get rust? I have a water filter, wonder if that would improve it at all?

[JpBinc]

No I did not ever get rust, and the stains are only on the alu not the steel.

[Geof]

Try an experiment, just wet some pieces of aluminum just with the distilled water you used, no coolant and see if you get any staining.

[JpBinc]

Great Idea I tried it with just the raw coolant and it did not stain but I did not even think about the water. I'll try it tonight and see.
Thanks
Jpbinc

[337MPH]

hey guys im having this same problem at work on a new machine we just got Mazak and when we take the parts out they are perfect all shiny but when they come back for the next OP they go in for like 4hrs and when we take them out they are stained we tested the water and seems to be coming from that its Deionized water but when its on a part and the stain is still under the water you can wipe it away but once it drys you pretty much polish it out any ideas?
Thanks
JM

[sc brian]

I have been using Kool Mist 78 and 77 on highly polished aluminum for quite some time. All of the sudden I am getting a black, brown or white stain on the parts if the coolant dries at all. I never have seen this until recently. I got concerned that the problem might be from the compressed air. Have checked the filtration, etc.

Any ideas? This is ruining every part. Kool Mist people switched me from 78 to 77 and told me to use distilled water. This did not change a thing.

[ALLtra Mach]

If you have been using the same coolant and have just now developed a problem, you might look in your resovoir to see what is growing in it?