G81 cycle problems


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  1. #1
    Registered psyon's Avatar
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    Default G81 cycle problems

    Hi Friends,
    We're using a G81 drilling cycle on plastic parts but we're finding the dwell at the bottom of the hole is too long and starts melting the plastic. We would like to remove the slight dwell time at the bottom of the hole which seems to be built into the canned G81 cycle.

    Does anyone know if a parameter of the G81 cycle can be changed to remove the dwell? Will I need to create my own canned cycle to accomplish this?

    Thank you for your help.



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    Flies Fast Superman's Avatar
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    Default Re: G81 cycle problems

    If you have a P value.. set it to zero
    else, program the cycle longhand using a G01 plunge with a G00 to retract...
    if there is still a lag at the bottom of the hole, then the issue is with the machine or controller



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    Default Re: G81 cycle problems

    Quote Originally Posted by psyon View Post
    Hi Friends,
    We're using a G81 drilling cycle on plastic parts but we're finding the dwell at the bottom of the hole is too long and starts melting the plastic. We would like to remove the slight dwell time at the bottom of the hole which seems to be built into the canned G81 cycle.

    Does anyone know if a parameter of the G81 cycle can be changed to remove the dwell? Will I need to create my own canned cycle to accomplish this?

    Thank you for your help.
    What is the machine control you are using, normally there is no dwell with a G81 that is just a Feed in Rapid out cycle

    How do you have the line of G-code written in your program

    Mactec54


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    Default Re: G81 cycle problems

    Fanuc 11m controller

    This happens in the g0 block after g01.
    Problem occurs in rapid traverse after cutting traverse.
    Cutting feed is normal after cutting feed.
    Rapid traverse is normal after rapid traverse.
    .
    G01 z-30. F100
    (Stop for about 2 seconds)
    G0 z30.



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    Default Re: G81 cycle problems

    Hi Pyson,

    Your code there has nothing to do with G81. I thought your question was about G81 drill cycle?

    Here is what a typical G81 drilling cycle looks like.

    T2M6 (DRILL)
    G17G21G40G49G54G80G90G98

    G0 X25. Y-20.
    G43 Z2.5 H2 S3050 M3 T3
    M8
    G98 G81 Z-30. R2.5 F100.
    X35.
    X50.
    Y-40.
    G80
    M9



    Those position moves are of course arbitrary.

    If you want to get better results out of what you have above, try staying in feed mode and not switching to rapid.

    G01 Z-30. F100.
    Z30.F8000.

    Plus I'm thinking if the control waits 2 seconds after the feed move and before the rapid move, the machine might have problems. Make the your machine is not stuck in Exact Stop Check Mode G61. Should be in regular cutting mode G64. Go into MDI and type in G64 EOB and hit cycle start. Then try your code again and see if there's any difference.

    Has anyone been messing with the parameters lately???

    Last edited by the_gentlegiant; 04-23-2020 at 10:51 AM. Reason: Added


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G81 cycle problems

G81 cycle problems