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IndustryArena Forum > GENERAL MANUFACTURING PROCESSES > MILLING > Milling FR4 PCBs, how hazardous?
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  1. #1

    Milling FR4 PCBs, how hazardous?

    Hi all.

    I have an old industrial CNC machine from a bygone era that I decided to repurpose for milling PCBs for another project of mine. While searching around forums for best practices i saw some posts saying that the dust created from milling the fiberglass board is quite hazardous, and dust collection and filtering is a must.

    I've only just got this machine running, I haven't actually tried to make a proper PCB, I just used one of the boards for playing around with etching letters into, but reading about this has made me gun shy.

    So my question is, should I be making or buying myself some sort of dust collector before I go any further into this? Is the risk that severe? What about an enclosure?

  2. #2
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    Re: Milling FR4 PCBs, how hazardous?

    I'm not an expert, but here's my thoughts on the subject:

    I wouldn't do this in the first place, because professionally made PCBs are so cheap now; and are drastically better than a milled one.

    However, if you still really want to; there's a few hazards to watch out for:

    1) Fiberglass dust is very abrasive. You need to keep it from getting in the machine parts. Otherwise you will kill your machine's accuracy very quickly.
    2) Although not nearly as bad as asbestos, fiberglass still isn't good for you. My understanding of the hazard is that it's mostly similar to silica dust: it gets in your lungs, blocks the air from getting to the gas (oxygen/co2) exchange membranes in there effectively choking you; and because it's largely chemically bio-inert (it's glass, after all), it never goes away. However, supposedly due to the shape of the fibers at a microscopic level (blunt ends, instead of very fine needle-like structures) it doesn't puncture cell walls like asbestos fibers do, and thus doesn't cause cancer (other things in the dust might, though).
    3) If your spindle can't go fast enough, you will either get poor cut quality or a broken bit.

    If I had to do this; I'd probably run it under a dedicated flood coolant system; and make a "tank" of sorts to sit on the mill table that would keep the fiberglass dust contaminated coolant off of the machine parts. I'd also see if I could come up with some sort of rubber boots or plastic bag setup to help shield the machine ways. I'd wear a respirator as well (running it wet should take care of the issue, but you only are issued one set of lungs, ya know?).


  3. #3
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    Re: Milling FR4 PCBs, how hazardous?

    Are you talking mass production or just making a couple PCBs for hobby use? I personally would not worry beyond basic precautions, such as wearing a dust mask and cleaning the table with a vacuum cleaner after the cut.

  4. #4
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    Re: Milling FR4 PCBs, how hazardous?

    Hi KM - Fibreglass is not like asbestos and silica. You could start by using your household vacuum cleaner. FG is very abrasive though. You can get a material safety data sheet (MSDS) from the FR4 supplier. This will tell you the best way to deal with the material. Boatbuilders have been living in FG dust for decades with no long term cancerous effects otherwise they would have banned the stuff long ago. (unless they are allergic to epoxy dust) So use a vac cleaner, keep the place clean, wash your hands etc all the usual keep tidy stuff. If you can get a industrial type dust collector all the better. Cheers Peter S

  5. #5
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    Re: Milling FR4 PCBs, how hazardous?

    Quote Originally Posted by peteeng View Post
    wash your hands
    Especially before going to bathroom. Certain parts of male anatomy do not respond well to fiberglass dust exposure.

  6. #6

    Re: Milling FR4 PCBs, how hazardous?

    Quote Originally Posted by __Britt View Post
    I'm not an expert, but here's my thoughts on the subject:

    I wouldn't do this in the first place, because professionally made PCBs are so cheap now; and are drastically better than a milled one.

    However, if you still really want to; there's a few hazards to watch out for:

    1) Fiberglass dust is very abrasive. You need to keep it from getting in the machine parts. Otherwise you will kill your machine's accuracy very quickly.
    2) Although not nearly as bad as asbestos, fiberglass still isn't good for you. My understanding of the hazard is that it's mostly similar to silica dust: it gets in your lungs, blocks the air from getting to the gas (oxygen/co2) exchange membranes in there effectively choking you; and because it's largely chemically bio-inert (it's glass, after all), it never goes away. However, supposedly due to the shape of the fibers at a microscopic level (blunt ends, instead of very fine needle-like structures) it doesn't puncture cell walls like asbestos fibers do, and thus doesn't cause cancer (other things in the dust might, though).
    3) If your spindle can't go fast enough, you will either get poor cut quality or a broken bit.

    If I had to do this; I'd probably run it under a dedicated flood coolant system; and make a "tank" of sorts to sit on the mill table that would keep the fiberglass dust contaminated coolant off of the machine parts. I'd also see if I could come up with some sort of rubber boots or plastic bag setup to help shield the machine ways. I'd wear a respirator as well (running it wet should take care of the issue, but you only are issued one set of lungs, ya know?).

    Yeah I know there's a few places out there like JLCPCB. I was hoping for this to be a sort of rapid prototyping method, because I'm designing a rather complex circuit using lots of SMD components from scratch and I don't really know what I'm doing. Sometimes I get a board in and I notice a fatal flaw quickly, and the whole board is a bust. I try to analyze the design as best I can before I send it out, but I always seem to miss things.

  7. #7

    Re: Milling FR4 PCBs, how hazardous?

    Quote Originally Posted by CitizenOfDreams View Post
    Are you talking mass production or just making a couple PCBs for hobby use? I personally would not worry beyond basic precautions, such as wearing a dust mask and cleaning the table with a vacuum cleaner after the cut.
    Yeah this will just be a couple PCBs for prototyping this circuit I'm working on. I actually have the Eagle files in github here https://github.com/katemonster33/CDJ..._Link/Hardware

    Dust mask for me is no problem, but should I be quarantining the machine to a small room so I can clean it easier? Right now it's in my basement, which is mostly unfinished, just a big room.

  8. #8
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    Re: Milling FR4 PCBs, how hazardous?

    Quote Originally Posted by katemonster View Post
    Dust mask for me is no problem, but should I be quarantining the machine to a small room so I can clean it easier? Right now it's in my basement, which is mostly unfinished, just a big room.
    I would not worry about it any more than you worry about wood or plastic dust. Same cleanup procedures should be OK.

  9. #9
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    Re: Milling FR4 PCBs, how hazardous?

    I would not worry about it any more than you worry about wood or plastic dust. Same cleanup procedures should be OK.
    I'm going to politely disagree just a little bit - wood and plastic dust tends to be less of a hazard to both human and machine; because a) your body can break down carbon-based materials, so it won't stay there forever (but I still wouldn't want to breathe either of them); and b) wood and plastic aren't nearly as bad to get in the machine ways, as it's generally not a harder material than what the machine is made out of.

    but should I be quarantining the machine to a small room so I can clean it easier?
    Yes, but I'd do that for any dust-producing process... sanding, high-speed routing, or even just using a hand-held wood router. Once it's in the air, dust has a way of getting everywhere...


  10. #10

    Re: Milling FR4 PCBs, how hazardous?

    Quote Originally Posted by __Britt View Post
    I'm going to politely disagree just a little bit - wood and plastic dust tends to be less of a hazard to both human and machine; because a) your body can break down carbon-based materials, so it won't stay there forever (but I still wouldn't want to breathe either of them); and b) wood and plastic aren't nearly as bad to get in the machine ways, as it's generally not a harder material than what the machine is made out of.



    Yes, but I'd do that for any dust-producing process... sanding, high-speed routing, or even just using a hand-held wood router. Once it's in the air, dust has a way of getting everywhere...

    OK! I think I'll put it in the plan to build a little enclosure for the machine, so I can trap any dust. For now I'll just be sure to wear dust masks

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