Plastics can make your coolant split?
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    Default Plastics can make your coolant split?

    Hi guys,

    Back in September the coolant in my CNC mill split -- the oil all separated from the water. Company tested the water and it was OK for PH and hardness, so they have no clear reason why it split. I have heard some anecdotal evidence that plastics, specifically acetal/Delrin, can contaminate coolant such that the oil de-emulsifies. I have gone through a lot of acetal this year, and was running coolant since most of the volume removed was in deep pockets that I needed to keep flushed out.

    Anybody else run into this?

    Thanks, and regards.

    Mike

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    Running any plastic with coolant on a machine where I also ran metal was just a PITA. All plastic has been run dry for the last 18 years. But I have machines for plastic only, and metal only. So no help here.
    White lie. A few years ago had to drill 20+xD into the edge of a phenolic 1" plate, 1/8 pipe tape the hole for a fitting. Peck drill with flood coolant. Only way to prevent melting the carbide tipped drill.

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    OT but nothing and absolutely nothing smells worse than my colleague's Okuma running plastic daily. I genuinely don't know how he can stand it, I can barely cope and I'm at the other end of the building...

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    Quote Originally Posted by Finegrain View Post
    Hi guys,

    Back in September the coolant in my CNC mill split -- the oil all separated from the water. Company tested the water and it was OK for PH and hardness, so they have no clear reason why it split. I have heard some anecdotal evidence that plastics, specifically acetal/Delrin, can contaminate coolant such that the oil de-emulsifies. I have gone through a lot of acetal this year, and was running coolant since most of the volume removed was in deep pockets that I needed to keep flushed out.

    Anybody else run into this?

    Thanks, and regards.

    Mike
    it doesnt split it persay but it will dilute the coolant faster.
    Splitting is just bizarre had it happen a few times, I was told it was due to the water hardness. we ran one job for 3/4 months all delrin everyday all day. never had it split.
    one nice thing about running plastics it takes all the tramp oils out, the bad thing is it takes some of the coolant out as well so you have to fill with a richer mixture.
    I have 6 machines one constantly splits usually after I shut it down for the weekend or longer and all its ran for 2 years is 321 and 303 stainless. the others dont split.

    since qualchem changed something a year or 2 ago my machines dont go sour anymore after sitting a few days just that one machine splitting.
    we also been running the machines a tad richer so that might be why were not seeing too many problems anymore.

    that being said I run qualchem 500c

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    Probably 50% of what we machine is plastics. Ultem, Acetal, FR-4, Polycarb, Semitron, Torlon, you get the idea. Going on 13 years now and have never, ever had an issue with coolant due to plastics. We have dumped a sump twice after switching from Blaser to Oemeta Hycut: Once for bacteria caused by dead spots in a coalescer, and once after the coolant sat for 4 months when we were evacuated during a wild fire. The coolant was fine after sitting that long (with plastic chips in it), but Oemeta wanted to ditch all the old coolant just to be on the safe side.

    We have one machine that filters the coolant to 25 microns before it goes back to the sump, and another machine that does not. Both have identical coolant maintenance done and I see no difference between the two as far as coolant quality and life. My bet is machining plastic is not your problem.

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    I the plastic is the problem, especially ones like polypropylene. The oils in coolants are not dissolved they are in suspension. We used to make oil coalescers that seperated the oils from machining coolants before we removed all the oil using ultrafiltration membranes. So coolant in contact with chips that have a high surface area very likely could coalesce the oil.


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