Hole Popper - Canned cycle, holes coming out different depth
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  1. #1
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    Default Hole Popper - Canned cycle, holes coming out different depth

    I'm brand new to EDM hole drilling. My machines are imported by Belmont from Taiwan- they are Yan Yang brand SY series. I'm drilling 6 holes using a canned cycle & the depth is coming out +/- .100". I haven't spotted any pattern yet like getting progressively shallower/deeper or 5th hole always deeper, etc.

    The documentation is fair, but I can't tell from the manual how hole depth is being adjusted to compensate for electrode wear. That seems like a possible cause, but may be totally wrong.

    Any ideas on possible other causes or explanation of how electrode wear is accounted for are greatly appreciated!

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    How deep are you drilling? Are you using a new electrode for each hole? Graphite tube? My experience is electrode wear is not consistent enough to get a repeatable accurate depth on a hole popper. We use our CNC sinker if accurate depth is needed.

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    Drilling about .5" deep, .019 dia. I'm not changing electrode between holes - it's a production job. Electrode is a brass tube. The depth is not super critical, I'm just thinking that somewhat better accuracy is possible.

    Thanks

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    Doesn`t the machine re-zero Z on each start up as soon as trode contacts top of part? I know the Current brands do this, should be alot closer than .100 on .500 deep I would think.

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    Hi TClark:
    I'll bet part of your problem is coming from the end condition of your trode whan you start the new hole.
    Poppers set the spark energy aggressively compared to normal sinkers, so the trode tip normally wears fast but reasonably symmetrically and reasonably flat.
    However, if you have an asymmetric tip after your first burn, the touch for the next hole will occur at the lowest point on the trode and when the new burn starts, that bit will disappear quickly and not contribute much to the making of the new hole until the flushing is sealed and symmetrical because the spark energy overcomes the ability of the pointy trode end to accommodate it especially with brass trodes so it just gets burned away.

    The trode will also tend to want to scoot sideways if the guide is up any distance above the job...are you having problems holding position too?
    Are your holes bellmouthed more than normal or oversized?

    Cheers

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

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    Thanks guys, the info about the sharp point wearing away quickly seems very plausible. I will see if I can figure a work around for that. I do try to keep the guide as close as possible to the top of the part because I'm drilling a .019" hole in .030 stock. I can't let the trode drift much at all. The holes are not bellmouthed enough to notice - a .021 pin gage wont start in at all.

    Thanks again Marcus & uncledenny for the ideas.

    Todd

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    It does seem to re-zero on each hole, maybe just not very well...

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    Are you focused on consistency or time. This is very important and difficult to get the best of both. Make sure each burn is the same. Smooth steady burn finishing at same time. You may need to increase burn time to get it. There could be a difference from new electrode to 2nd hole.

    Also - are these blind or through holes??

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    Larry, I'm more worried about the consistency, at least for now. I've actually started getting decent results using a smaller diameter trode and burning "hotter." I was trying to use a .0177 electrode to make a .0194 hole, so I had to go really slow. Dropping down to .0157 lets me burn much faster and actually seems much more repeatable so far. These are blind holes and now I am holding ~ =/- .010 depth, which is good enough for the application.

    My best guess is that the spark is much stronger now, so maybe re-zeroing z when the electrode touches each part is working more accurately.

    Thanks to all for the input!
    Todd

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    Definetly rezero! Good to hear.


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