Coolant problem

Hello,

so we have a Mazak Quick Turn Smart 200M and we filled it up with a semi synthetic coolant. It was okay for a while but all of a sudden the coolant becomes diluted. Oils float to surface, and the % of the concentrate mixture goes down. It's like the concentrate evaporates or something.We had no problems with this coolant before, now all of a sudden it has become a problem.
We also installed an oil skimmer, but oil keep coming back.
Coolant is semi-synthetic, has no cloride, without secondary amines, without formaldehyde and it doesn't foam. The materials we cut are Aluminium 2017 or 2030 and Steel 11SMnPb37. Lubricating oil is OLMAPOLAR 68D, and Hydraulic oil is MOBIL DTE 24 if this helps.
Last year we changed the water source, so judging by the other topics I've read on a similar situation this might be the problem. What substance in water causes the mixture to demulsify? What should I look for?

Thanks for the answers!

There's two possible reasons here, the first is that somehow the coolant became contaminated with another chemical, the other is that it was caused by your water

If the problem started immediately when your water changed it's likely that. Hard water can be a culprit, all those extra ions and such which are bonded stronger to water than soluble oil can ever be, like when you keep dissolving salt and eventually it hit's the limit and won't dissolve anymore, the ions make the water hit the limit sooner and force the oil out (or at least I think that's how it works) If you identify water as the problem you could source the water somewhere else (I had to do that once or twice recently when the water board temporarily switched the factory to bore hole water) or get one of many available water softening systems

If it's become contaminated then draining the tank, cleaning and refilling should do the trick. You mention your lubricating and hydraulic oil, have you recently changed them? If not have you checked for leaks in the hydraulics that could cause more oil to contact the coolant?

One thing that happens is that the dissolved solids increases over time as evaporation takes place and more water is added for makeup. This in essence makes the water harder over time. What worked today might not work in the future.

Boilers over come the problem via periodic blowdowns. Depending on what your exact procedure is for make up water and the source, you might need to consider either dumping your coolant more frequently or else periodic removal of some of the coolant and replacing the volume with fresh water to lower the dissolved solids.

Thank you for the replies, it helped alot. We did a water hardness test and it seem that our water is a bit too hard about 270ppm (mg CaCO3/l). Well I hope this is the problem so that we can start working on a solution.

HappyChappy said:

Thank you for the replies, it helped alot. We did a water hardness test and it seem that our water is a bit too hard about 270ppm (mg CaCO3/l). Well I hope this is the problem so that we can start working on a solution.

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I uses a Reverse Osmosis system from Home Depot, $150, it will make about 15gallons of RO water a day. It's a household unit. I would assume something similar is availible in Slovenia

triumph406 said:

I uses a Reverse Osmosis system from Home Depot, $150, it will make about 15gallons of RO water a day. It's a household unit. I would assume something similar is availible in Slovenia

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Thank you very much! I think my boss won't be so upset about this price!

Bad batches of coolant happen too, or if it froze during transit to your shop, some coolants don't like that.