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  1. #1
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    Join Date
    Mar 2019
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    1

    Bar Feeder Issue

    I work for a small company running and maintaining 4 CNC machines, 1 of the bar feeders has a huge problem, when the program begins to run it faces the tool, then it is supposed to bring the bar to z .06 and stop then begin another phase of cuts, instead it continues to push the bar and break the tooling and error out, the strange thing is i have this program on 2 other identical machines and they run without this issue, also it only happens randomly, it can make 10k parts without doing this and then it just happens... im thinking its a sensor issue of some sort possibly, i do not have schooling to run these machines I only know what ive been taught and learned through trial and error, any help would be great... Thank You... The bar feeder is a Genius 120/37 made by IEMCA

  2. #2
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    Join Date
    Mar 2019
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    1
    This definitely sounds like a sensor issue with the barfeeder not sensing properly. The only way to correct this is to locate and check the sensor; make sure the wiring is tight and possibly clean the sensor depending on the type of sensor.
    It is difficult to really provide any details since I cannot see or touch your machine.

    I am a Field Service Engineer for FIVES machining After market support. Our techs and support team are available worldwide. Our local west coast office is in Valencia, Ca and can be reached at 818-678-2285. If you are not in this area, they can give you your local office contact info. We are Fadal, Cincinnati, Giddings and Lewis and many other brands. We are the manufacturers; we can help you!

  3. #3
    Member
    Join Date
    Jun 2015
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    2729

    Re: Bar Feeder Issue

    hi benjamneanos i have also encountered this sporadic thing on a iemca : sometimes it works, sometimes it pushes too much


    in the end, i have no longer used to stop the material on the cutting insert, simply because it was pushing it with too much force; this is hard to see, because the impact is very short, and if there is oil on the window, etc, it makes it even harder to spot this thing; to detect it, i have put a comparator dial inside the machine, and sometimes the shock would move the dial with a couple of tents ( 0.2 - 0.7 ; longer inserts tend to bend more ) ... so i decided that i have to remove this shock from the machine, or at least to avoid bumping my insert, so i have rewritten the code, to push not on the insert, but on a toolholder as a result, cutting insert would last much longer, and the cutting edge would remain sharp, getting wear only from cutting, not also from bumping


    there is a parameter that controls the push force of the feeder : if you reduce it, it will have imediat effect but, on the long term, there may be problems :
    ... a longer bar needs more push force, and a shorter bar needs less push force, so, as the bar gets shorter, the shocks will increase, thus there will be much more pressure on the cutting insert when the bar is near it's end
    ... in time, the intermediate sleeve may get loose, and tightening it is not exact science, so is not quantificable how big is the fraction of the servo that must overcome the force of the intermediate sleeve

    the strange thing is i have this program on 2 other identical machines and they run without this issue
    even if code is identical, there are some variables :
    ... feeder torque
    ... bar length / mass
    ... intermediate sleeve friction, etc

    kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  4. #4
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    Join Date
    Jun 2015
    Posts
    2729

    Re: Bar Feeder Issue

    hello again benjameanos, just a few more things :

    - pushing is all about timings, collet opens, and the feeder start to push until it hits something; the feeder does not know that the collet is open, it simply pushes continuous, all the time ... but things get a bit. just a bit, more complex during the bar change sequence : feeder must retreat the remnant, and he does a few things only after the collet opened : actually, the feeder does not know that the collet was opened, but only that there was a code that sends a signal to open the collet, thus the feeder does not move based on a confirmation code there are some parameters for "dwell" inside the feeder, only to achieve a propper timing

    - if you take those 2 things, from above, written with blue, then is easy to see that the feeder is (almost) always in tension; at least on iemca, on some models, etc, this leads to origin lost, and is ok to 'zero it' from time to time : i ' zero it ' every day 1st time when i 'zero it', it was shifted with 9mm, but this was at the begining ... ' zero ' may be lost after a long term operation, or after a sudden failure; there are ( at least ) 2 methods to verify the 'zero' :
    ... inside the cnc cabinet. look how long is the new bar when it is bringed for the 1st cut off operation : if 'zero' moves, then the bar will also shift
    ... operate the feeder in manual mode, and move it to retreat position, and check the coordinate displayed on the feeder remote


    ok ... now, about sudden failures when changing : sometimes, the feeder keeps on pushing, aparently without a reason, but, i noticed that actually it repeats the ' bar change macro ', and something happens, something gets lost, i don't know what, and he pushes like crazy : to handle this, i have used variables ( couting parts ) inside the feeder macro, and if it accidentaly tries to run that macro, it will be stopped if this action was performed recently ( no more than 'x' parts were cut ); in my case, the feeder was ocasionaly repeating only after the 1st part, so i needed to 'block' this potential behaviour that may have occured on 2nd part ... i was lucky, because there was a patern, thus ocasionaly only after 1st part was machined / kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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