Simple Question: Stable Reduction Value for Tech Optimization? (WEDM)
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  1. #1
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    Default Simple Question: Stable Reduction Value for Tech Optimization? (WEDM)

    So, I'm going to start attempting to optimize my cutting speed using a job that takes an infamously long time to cut, but is generally easy to re-thread broken wire. Sources I've found say that the first step to increasing cut time is to reduce the off-time, then the servo gap voltage, or even the wire tension so that the other two values can be reduced more aggressively. The machine in question is a Fanuc, and the Methods trainer said something similar, so I feel confident that making these changes will incur... some sort of result.

    My question is, for those who are experienced in optimizing their technologies, what is a safe-ish reduction increment for off-time and servo gap voltage, to avoid immediate wire breaks? I'm positive that there is no definitive answer, but any examples will help me find a number that works for me!

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    Hi Ishira:
    This is such a loaded question, it's hard to know where to begin.
    Let's start with the basic proposition...you want to cut faster than you are currently doing, and you want to optimize your process to do that.
    Set aside for the moment, the cut settings you can jigger; we'll get back to them.

    OK, lets start with the machine...you can hugely influence its performance by maintaining it properly, and by fixing it when it gets fucked up.
    Flush cups filters DI resin power contacts discharge cables wire transport parts etc etc are all relevant to the performance of the machine and will affect its cut speed in a significant way.

    If it's in good shape with respect to maintenance, that's great but it will also get tired in other ways.
    Wires don't age all that gracefully; they have to manage large currents under harsh conditions so after a while computers start to go and motors get marginal and capacitors get ill and etc etc.
    Chillers plug up, pump seals wear, powder brakes get clumpy, pinch rollers get sloppy conductivity probes die, etc etc.

    Also technology gets better over time so if you're hoping to race with the newest and best but you have a 15 year old nag harnessed between the shafts of your kart. it's never going to fly.

    Next, the things you can influence:
    What wire are you using?
    Plain brass?
    Stratified?
    Engineered for best performance with your machine?
    Ideal for your material?

    How fast are you running it?

    How cool and how clean are you keeping your water?
    How well can you control its conductivity?

    Now, at long last, we get to the crux of your question: jiggering the settings.
    On most machines, for a very long time now, the settings recommended by the machine maker have been optimized to give predictable performance under idealized conditions (clean material, sealed flushing, well maintained machine etc etc).
    If you follow the formula, you will get minimal wire breaks, your parts will come out on size and they will have the finish you expect, all in a reasonable time.

    Whenever you deviate from that, you need to anticipate that something will change and you will need to do empirical tests to see what you get.
    For example; just by manipulating my wire speed and tension I can make a straight cut or I can make an hourglass shaped cut or I can make a barrel shaped cut, or I can make a tapered cut.
    By manipulating the spark characteristics I can make bigger parts or smaller parts or smoother parts or rougher parts.

    So the gold standard is to do test cuts and interrogate the results every time you need to deviate from known cutting conditions, and of course you do this by deciding what your goal is and seeing how your change works with respect to that goal.
    The other rule of thumb is to deviate only when you must, most commonly because of wire breaks.
    Yes you can optimize for a specific characteristic (in your case speed) but you do it empirically and you figure out what will happen in other domains when you do.

    The trick if you want to do this is to be organized and methodical.
    Change ONE THING at a time and change it incrementally enough that you get to a point where the differences are measurable.
    Then select another thing and do the same.
    Once you've gone through all the things, pick the ones that trended to the desired effect and work two of them together.
    Then three, then four until you run out of things to change.
    Document everything.

    Once you go through all this you will have a pissed off boss, a mountain of cut up stock, a pile of used wire and a whole lot of knowledge that will gain you maybe 5 or 10% cut speed gain at the cost of other things.
    Just keeping the machine in good nick instead, will gain you an easy 10% or more so it's a better more sure investment.

    Most people I know have done it once and never again.
    They use the stock setting whenever they can, and jigger with it only when they must.
    If they have a special need, they call a factory applications engineer and ask them to optimize the process for them for their material and their machine model.
    Then they spend what it takes to bring the machine back to excellent condition and go at it.


    Cheers

    Marcus
    Implant Mechanix • Design & Innovation > HOME
    Vancouver Wire EDM -- Wire EDM Machining
    Last edited by implmex; 10-08-2021 at 12:18 PM.

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    As Marcus said, messing with settings can net you some gains but the net result tends to really not be worth it. Wire edm inherently cuts slow and very accurately. Gains are usually measured in .010s or maybe .100 inches per minute. Wire size can make a huge difference as well, just moving from 10 to 12 zinc coated Wire can really speed things up.

    I would encourage you to talk with an app-eng at methods, this could really help.

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    Ishira,

    I've been out of the wire business now for about 10 years, but can tell you that I found pretty much what Implmex has outlined in detail:

    Keep the machine clean, keep the water clean, keep conductivity as low as possible, keep a stable water temp, and above all... make sure that there is good flushing on your job.

    In my own experience, the only thing that made noticeable changes in speed (on certain materials) were coated wires. And interestingly, almost always without changing settings.

    PM

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    Thank you for the input everyone! I appreciate the responses.


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