Small Hole EDM Tips
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  1. #1
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    Default Small Hole EDM Tips

    I just purchased a new Yougar small hold edm. I am completely new to the EDM game. Most of the holes I wanted to burn are in the .009" - .016" range and are chasing a slightly smaller hole that is around a .040" deep through hole.

    I am having trouble with these smaller holes. Here are some of the problems I have:

    Through hole in electrode will close off
    Electrode will "burn" in the middle (between the guide and the chuck)
    Wont burn through (guessing from one or both of the previous)
    Leaves slag on the outside of hole

    Machine does have a soft start. Using brass electrodes on a somewhat similar material to tool steel. They are fuel injector nozzles for diesels.

    Tech guy that set it up couldn't even get the thing to work properly on the smaller holes. It will do ok on the larger holes.

    Looking for any tips

  2. #2
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    Hi shortbusdriver:
    You say your holes are not into the solid but are into pre-existing through holes that need to be opened up.
    I believe that this is the root cause of your problem; you have no flushing pressure because the water is just pissing through the existing hole, so there is nothing to flush the burn and it stalls with all of what you describe as a result.

    Also: you say these are diesel fuel injector bores...do they not have to be super precision holes?
    You have what looks to be a standard hole popper which is really not designed for this purpose unless the Yougar website is totally misleading.

    Were you sold the machine with the promise that it could do this kind of work?
    Did they offer a drilled sample as proof it would work?
    Did you see the spec where these machines claim to be good only down to 0.3 mm (0.012") diameter?

    To see what is considered to be the normal standard for this sort of work, visit the Sarix or Makino websites.

    These kinds of bores are commonly machined with a solid electrode that is wire edm cut right on the machine to make it perfectly concentric and of a very accurate known cylindricity.
    These specialty small hole EDM machines can make a 0.004" hole dead nuts accurate within a tenth or better but they cost a fortune to buy.
    They are not your bog standard hole popper.

    I fear you may have been sold an inappropriate machine, unless I'm completely misunderstanding what you are trying to do and what the Yougar machine is actually made to do, but from what I see on their website, it sure looks like a standard hole popper to me.

    If you want some in-depth information on how to best achieve what you plan to do, I'd be inclined to contact Brian Pfluger at Makino.
    He's a contributor to this forum and knows this turf extremely well.
    If anyone can point you in the right direction, he can.

    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining

  3. #3
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    Default

    Thanks for the response. Here is my replys.


    Quote Originally Posted by implmex View Post
    Hi shortbusdriver:
    You say your holes are not into the solid but are into pre-existing through holes that need to be opened up.
    I believe that this is the root cause of your problem; you have no flushing pressure because the water is just pissing through the existing hole, so there is nothing to flush the burn and it stalls with all of what you describe as a result.
    I have it set up so the through hole is blocked on the back side. It is then a blind hole so it "should" be flushing properly.

    Also: you say these are diesel fuel injector bores...do they not have to be super precision holes?
    This is mechanical diesel nozzles. EDM is common on these as long as its a decent job.


    Were you sold the machine with the promise that it could do this kind of work?
    Yes, I had two different companies say this machine could do what I needed.

    Did they offer a drilled sample as proof it would work?
    Yes, they burned some holes for me at their showroom when I checked the machine out. However it was a bigger hole then what I would be using it for.

    Did you see the spec where these machines claim to be good only down to 0.3 mm (0.012") diameter?
    Yes, the machine is "suppose" to go down to .1 mm.

  4. #4
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    I have it set up so the through hole is blocked on the back side. It is then a blind hole so it "should" be flushing properly.

    Nope, incorrect thinking! While you may have the flushing, the electrode isn't seeing a full contact and it will wear unevenly.

    Yes, they burned some holes for me at their showroom when I checked the machine out. However it was a bigger hole then what I would be using it for.

    Well, the reason they've used a bigger electrode is because it does not have a fine enough control to use smaller ( .4-ish and under ) electrodes.

    Yes, the machine is "suppose" to go down to .1 mm.

    See above. The statement "suppose to go down to" should be demonstrated and not just claimed.

    Believe me, everyone with a Makino, Sarix or Current EDM drill has a good enough reason for those machines, regardless of price!





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