Surface Grinder Coolant Filtration
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  1. #1
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    Default Surface Grinder Coolant Filtration

    First off, I want to thank everyone who has contributed to this topic to date. There is a lot of great info on here... just wish people used more accurate post titles, to improve searches for specific subject matter.

    That said, I have read through several posts about filtration systems on surface grinders and wondered if anyone has tried reticulated foam and or spunbond polyester pre-filter media, similar to air or aquarium type filter media? Obviously I'm speaking more towards smaller shops, lacking the necessity or budget to install a high-end or complex seperation system.

    I just got through cleaning what might have been ten (or more) years of slop, sludge and disgusting from our surface grinder. So before I put fresh coolant in the reservoir I thought I would add even a low budget method of prefiltration...

    If anyone has tried the above mentioned let me know how it worked out? Keep in mind I'm going from absolutely nothing, in terms of pre-filter or oil seperation, to seemingly the most basic.

    Thanks 😊

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    What about this?

    Chip Tray Filter Kit

    You could replace the coarse material they use with regular paper filter for coolant/liquids?

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    We use both filter paper and magnetic separators and both work well. Non magnetic work piece , of course you should go with a paper filter. I would say we prefer the magnetic (less frequent attention). The paper you need to keep up with tearing off used , wet paper and disposing of it, the magnetic, you just empty the collection bin. We grind 85% magnetic steel, 15% non magnetic stainless and aluminium.

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    Jarrod,

    On our small Okamoto 1020, it has a bed type filter with a roll of 5uM filter paper, and we still get sludge in the coolant tank. I added an additional settling tank prior to the coolant going into the main tank. I have in the past used Scotch Brite pads as a filter; they seemed to catch the fine particles pretty well.

    On our larger Okamoto grinder, it actually has two vertical "hurricane type" filters that seem to work pretty well.

    This leads me to another thought that I will start a separate post on.

    Mark

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    The Okamoto I've used the most has a large paper filter roll, I'm not sure of the pore size off hand. It's on a large roll and has a simple float switch to advance it when it starts to fill. Not all that different than a big filter roller for marine aquariums, but of course upsized. I suspect that draining through filter socks would be similar and easy to implement, although I don't know what the changeout frequency would be.
    Filter roll material can be purchased online in whatever size you want, so rigging something up wouldn't be all that difficult.

    Haven't had any oil separation issues as there isn't much oil in that shop, but a previous place I worked liked to leave a sheet of pig mat floating in the CNC lathe sumps upstream of the last baffle (to keep it out of the pump). It absorbed tramp oil without messing up the coolant and would get changed out when it stopped working.

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    Not a bad idea either, but I was actually planning to fins a fine metal screen as the top level pre-filter.
    Quote Originally Posted by Mike1974 View Post
    What about this?

    Chip Tray Filter Kit

    You could replace the coarse material they use with regular paper filter for coolant/liquids?

  7. Likes Janderso liked this post
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    Quote Originally Posted by RJT View Post
    ...of course you should go with a paper filter...
    Is this a premade pleated filter or literally just sheets of filter paper in some arrangement? Any idea what size particle they're rated for?

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    Quote Originally Posted by Jarrod View Post
    Is this a premade pleated filter or literally just sheets of filter paper in some arrangement? Any idea what size particle they're rated for?
    The one I use looks more like a giant roll of paper towels.

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    Quote Originally Posted by M. Roberts View Post
    Jarrod,
    ... I have in the past used Scotch Brite pads as a filter; they seemed to catch the fine particles pretty well.
    Mark
    Thanks for the insight, Mark. I'm surprised even a 5 micron filter isn't perfect. What grit of wheel are you running?

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    Quote Originally Posted by jccaclimber View Post
    ...draining through filter socks would be similar and easy to implement, although I don't know what the changeout frequency would be.
    Filter roll material can be purchased online in whatever size you want, so rigging something up wouldn't be all that difficult.

    Haven't had any oil separation issues as there isn't much oil in that shop, but a previous place I worked liked to leave a sheet of pig mat floating in the CNC lathe sumps upstream of the last baffle (to keep it out of the pump). It absorbed tramp oil without messing up the coolant and would get changed out when it stopped working.
    Not a bad idea at all. I looked at those filter socks as they came up in another post, but I'm not sure I have the space to make them work well.
    The grinder is a G. Brand machine, which has an outlet tray from the table, going down a pipe to a second tray before going into a two section reservoir.

    I was going to throw in some oil absorbent sheets to the mix as well!

    I don't have any macro icons for adding pictures and so forth, so here's what it looks like: Google Drive: Sign-in

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    I'm making a few assumptions based on those photos, but if I wanted to rig a filter sock I'd have it hanging right on the drain of the second tray. Some sort of large funnel around the sock would ensure coolant overflow ends up where it's supposed to. A 5 gallon bucket with a hole in the bottom where the drain would normally go would make a quick containment vessel for the sock. In the case of large filter rollers it's a sheet of filter material supported by a chain conveyor right over the coolant tank.

    You can stretch the life of filter socks by nesting them, IE put a 20 m sock inside a 5 m sock. The 20 m catches most things, and the 5 m only catches 5 to 20 m particles. It may turn out that there aren't actually many fines, in which case the 5 m sock alone would be fine.

    Here's a stolen from Google image that is similar to the Okamoto setup:
    coolant-filter-paper-1525245156-3820463.jpg

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    On my manual 6x12 I use the last foot or so of pantyhose on the end of the return. It catches a lot of the swarf but not 100%.

    I don't do a lot of surface grinding but for me it works well and it's inexpensive. And the looks you get from the cashier when buying them are priceless .

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    Quote Originally Posted by Jarrod View Post
    .... and wondered if anyone has tried reticulated foam and or spunbond polyester pre-filter media, similar to air or aquarium type filter media?
    Yes I have.
    You will still get sludge in the tank.
    For heavy duty steel grinding where you actually make slivers and chips it helps some. For fine grinding it does very little.
    Like the nylon sock some attach a bag filter to the drop spout.
    Any gravity fed system needs either big holes or often change out like a drag system as it will plug and overflow.
    Best for me is prefliter or fine screen, long path settling tank with baffles that force a up and down motion of the coolant, and a final cartridge or pressurized bag canister after the pump.

    In the settling tank one can take collect a sample of the outgoing coolant in a glass jar, set it aside and time how long for the coolant to become clean to your liking.
    This information plus your flow rate tells you how long the path needs to be but still leaves you the fun of tank cleaning.
    Bob

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    Jarrod,

    To answer your question a few posts back; we mainly run 100g vitrified or resin bonded diamond wheels. To boot, 90% of our work is with ceramics so the swarf is non magnetic, and pretty fine. The 1020 Okamoto has a bed filter with 5 micron paper; the larger machine has the hurricane type cartridge filters; not sure of the micron size.

    Back in the day, at a previous employer, we ran 10 or so small Harig slicer/grinders, and a few small rotary grinders; the machines were arranged in a square, and all were fed from a central coolant tank equipped with a centrifuge, which seemed to work pretty well...

    Mark


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