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Mist collectors for surface grinders

M. Roberts

Cast Iron
May 11, 2021
Hello all. We have a few Okamoto surface grinders; 3 1632 machines, 1 820, and expecting a 2448 machine soon. Two of these are located in a small R&D shop along with a HAAS VF2. We noticed the air intake above the VF2 was turning black, assumably from the coolant mist coming from the open surface grinders. I had mist collectors installed on all three machines. The grinders have two intake ports; one directly in the shroud surrounding the wheel, and another down stream of the coolant flow coming off the grinding wheel/workpiece. The VF2, being that it is an enclosed machine, I do not figure this being a major contributing factor to the issue. After all of this, the filters on the HVAC system are still turning black within a few days....does anyone have any constructive thoughts or ideas? Thanks in advance, Mark
Still, you can't get all the mist.
I completely agree. Even a completely closed casing around the entire machine does not provide 100% protection against haze. This muck always finds some gap or hole :(
On my surface grinder, I did two things to combat fog: counter coolant from the opposite side of the wheel, and suction of the mist directly from the wheel guard. Of course, then the suction line passes through the mist settling device.
Good morning. EKretz, that is a good idea; I could change the filter on a Friday, and check it on Monday to see the difference, but nothing would be running over the weekend either....not running the grinders would not allow the boss to purchase another porsche...:). I attached a pic of the typical install of the mist collector. The units themselves are manufactured by Micro Air...they seem to be operating properly. Is it a health issue?? I have read elsewhere on this forum about people having health issues stemming from long term exposure to coolant/mist from coolant.


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Qt (:(allow the boss to purchase another Porsche.)
Last time I saw my friend Scott (at fish camp) he mentioned "I pay my guys very well, it's not fair to have a cottage on the lake and pay people crap wages.
He does not have a machine shop, but has auto parts and home improvement supplies stores.
I know if big chain stores get too close they will put a strain on his logic.
*But let's not hack the thread subject by discussing this.

On topic, we used to use a 1/16 rubber hose bumped close to the OD of a straight and face-use diamond wheel so as to have the wheel plenty wet, with not a whole lot of coolant.
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MB, are you suggesting that the coolant flow is too much? Are you able to share a pic of your setup? I did a little digging on the mist collectors; they are rated at 600 CFM...not much, but again, we are looking at collecting the fine mist...I guess that we aren't doing a good job at that, are we
QT (are you suggesting that the coolant flow is too much?)
No, you get mist with any coolant use, sometimes a carbide grinding can have less coolant, but well directed. some work needs flood.

Other than a fully enclosed machine you will get sone mist.
Wadded up sections of a screen door in the intake tubes act as a coolant impinger and spark arrestor.
Also all tubes should have a goodly downhill slant to the machine so the water/mist goes back to the machine and not into the filter system.
Yours seem level and no drain hose.
Good morning. Yes, the units are new. I believe that they vent out of the back...need to double check that. They do have a drain that leads back into the coolant tank of the machine; just a bad camera angle. The intake could have more of a pitch than it does, but it does slope towards the machine. While in operation, the needle on the magnehelic is in the center of the range...so its not like the filter is plugged...
I should clarify... Do they exhaust outside or inside the shop? If they are not functioning properly and vent inside they are essentially doing nothing.
Just something to check good luck!
Steve, I believe they vent out the side, and back into the shop. Good point, exactly my thoughts; either there is too much suction (which there isn't) and it is blowing by the filters, or the filters are crap....