Do all fanuc based machines over travel?


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Thread: Do all fanuc based machines over travel?

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    Default Do all fanuc based machines over travel?

    Hey everyone, ive been working fulltime in a machine shop for about 8 months now, started from pushing a button to programming and setting up lathes and mills and am learning a swiss lathe at the moment which basically led me to my question.

    We have 2 miyano bnc lathes, and a leadwell which are all fanuc based and will overtravel. We also have an older matsurra but it is based on a yasnac control and overtravels as well; which led me to the assumption that because they are all older 10-20 year old machines that the technology (im not even sure what this is) to prevent over travelling didnt exist.

    Our other machines include a milltronics mill, a haas vf3 and a citizen l20, all of which are not fanuc based and are fairly "new"; the millttronics and citizen are less than 5 years old and the haas is about 10 years, so my previous theory seemed to work out, until..

    ..We got ourselves a citizen K16 which is fanuc based.. (this one is kind of "mine", ive learned most of my swiss knowledge and programming from our L20, but since im new my boss is letting me be the one to learn the machine). I found out today that it does indeed overtravel, when our L20 does not. I figured being a swiss lathe of the calibre it is and its age that overtravel would not be a headache to deal with but I was wrong.

    So my theory of older machines overtravelling and new ones not was thrown out the window.

    Aside from the yasnac, fanuc control and servos/motors seems to be the only common denominator.

    So why? What exactly is the reason for this?

    Im not so weathered on the maintenance and true mechanical properties of the machines, but my basic knowledge includes a ballscrew attached to the servo which moves the axis around.. our machines that dont overtravel are designed this same way, so what gives, surely if other manufacturers have worked around this, then fanuc could right?

    Sorry for the long drawn out post :P

    Thanks!

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    Community Moderator Al_The_Man's Avatar
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    Most systems, Fanuc included have software (parameter) limits as well as hardware limits to prevent overtraveling causing damage.
    In ,many cases, the software limit is either not set up correctly, if at all.
    The idea of the software limit is to prevent ever reaching the physical overtravel limit.
    Al.

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    Software limits are provided because it is desirable not to reach hardware limits. A hardware limit causes emergency stop, and you need to start again (at least this happens on my machine). A software limit does cause alarm, but you can manually move the tool to the permitted zone, reset the control, and alarm goes away.
    In some cases, software limit has to be used. For example, you may have a hardware limit for a chuck of a particular size (so that the tool does not hit the chuck). Now, if you replace the chuck with a chuck of a different size, the position of hardware limit switch would become incorrect. It may or may not be possible to shift the hardware limit switch on the machine (fixing holes may not be at the right place). But, you can define any position as software limit.



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    Member christinandavid's Avatar
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    Default Limit Switch

    Hi,

    Having gone from Heidenhain to Fanuc, I too find it annoying that machine will happily travel to the software limit and then alarm out, requiring the aforementioned jog and reset to continue. It would be nice if the control could inhibit further axis movement without bringing up an alarm and when in cycle mode, as on Heidenhain, predict the occurrance before performing the movement.

    DP



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    I have to add that if you purchase a new machine, the MTB may not have put the hardware as well as software limits at the right place. I realised this only after the tool actually hit the chuck due to a programming mistake on my machine. So, on a new machine, before you start working, move the tool manually to check if it enters dangerous area.



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    is very simple theory

    every machine ,but every machine, has a soft limit that u can adjust as u wish.
    after that limit that is write down in parameters depending on what type of fanuc u have,is a limit switch for emergency limit.
    many of machines from nowdays has also a mechanical stop that is a round rubber on ballscrew at the end or somewhere else .
    if machine pass the soft limit and the limit switch is not working will go more and will hit everything because u have some more space on ball screw .

    so they put a round rubber to stop machine slowly and not to be IRON CRASH IRON so will prevent damaging

    i think in u case all parameters for soft limits are lokk like 9999999,-999999
    so u have to put the corect ones



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    Well I understand that there are soft limits and hard limits, and when it overtravels its usually a soft stop unless of course you rapid past hte stop.. then things can get hairy.

    But on our machines that dont over travel, I can jog and all the way to the end of the axis and the machine just stops at that point, no matter how fast I seem to turn the jog handle, the machine just stops and is happy to continue doing its thing



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    hi

    from what u say i am not exactly able to understand u problem
    if u can give us an example of what u want to do with the axes and what machine do real.

    u say is overtravel before to reach the limit?
    give me an example how u do and what is happening

    i think i can help u

    cu m8



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    Member dcoupar's Avatar
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    If it makes your life easier, most newer Fanuc controls have a parameter that automatically clears the alarm when you jog the offending axis off the "stop" (no RESET necessary).

    There may even be a parameter that controls whether the alarm is issued at all, but I haven't found it yet.



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    now i understand u
    should be like a warning or some of operator alarms that don't stop the proces just it say for information

    say what type of fanuc u have and i will look for the parameter

    ps:i know that new fanuc have that option.



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    Quote Originally Posted by zavateandu View Post
    now i understand u
    should be like a warning or some of operator alarms that don't stop the proces just it say for information

    say what type of fanuc u have and i will look for the parameter

    ps:i know that new fanuc have that option.
    Sorry... I was replying to glenthemann



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    im not having any problem, im not looking for any parameters to have it automatically clear the alarm once the axis is moved off of its stop. I am wondering why it is that OTHER manufacturers machines do NOT overtravel. Soft or hard limits or not, these machines just dont overtravel. They stop right at their limit no matter how much more you move your jog handle. There are no alarms or overtravels, the machine just simply stops. Ie. if I move x towards its return position x0 then the machine will stop at x0 whereas it seems the fanuc will just happily move past that point and then send you a message saying you overtravelled.

    I just dont understand how other companies get aorund this silly overtravel business and yet fanuc which as far as I know is one of the oldest and top NC/servo/motor companies around, hasnt ever worked this out?



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    Are these other machines tripping a switch at the end of their motion ?

    normally if you reach the end of travel you will see a message or alarm because of the SWL but if it is hitting a switch, that switch can either be hooked into the EM-ST i.e. a HWL or, through the PLC it isnt hard to just inhibit all jog movements with out giving an alarm.

    you need the HWL only really on incremental encoder type machines where you get jog movement before you have referenced machines which aligns the SWL with the ends of the axis.

    To answer your question it really depends on how the MTB decides to setup the machine.

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    I agree 100%. The soft limit alarm is annoying for sure. Okuma's never give a soft alarm, they just stop motion and the limit lamp comes on. No resetting required. My guess it's from the fact the controls can be configured for any automation process, not just machine tools.



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    Hello. I think i understand where your confusion is. All machines have overtravel. What you are seeing is not overtravel. You stated in your last post the thing that gave it away for me and your issue. You said X0. Your zero position is not your overtravel position. They are two totaly different things. You are using the pulse wheel to move your axis to your X0 position, then when you get there you can go farther until it reads overtravel. There are 3 levels of what you are looking at. Hard overtravels first, then inside this window comes the soft or (user)limits. These may also be refered to as your work envelope. Then the Zero positions are located within the Soft limits. It seems to me you are getting confused between what the zero and limits are. Remember, your X-Zero is not your overtravel. When you tell the machine in your program or using MDI to go to Zero then it will go there and stop, but this is your zero point, not your overtravel point. Trust me when i tell you that all cnc machines if they are worth a crap have overtravels. Some machines do use absolute encoders so you may not see switches anymore but there is still an overtravel that goes by an encoder count that will be set in an overtravel parameter.



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    CNCZILLA:

    I don't think he's confused, I think he wants to know why some controls (Haas, Okuma, etc.) will just stop moving when they reach the end of travel... no alarm is issued. Fanuc's will go past the end of travel by an amount set in a parameter (usually 1 or 2mm) then issue an alarm.

    glenthemann:

    My guess as to WHY Fanuc hasn't "worked this out"? They probably don't feel they NEED to work it out. It is what it is and any CNC operator who runs Fanuc's is used to it. I'll bet there's even some Fanuc jocks who've jogged to the end of travel on a Haas and wondered why it DOESN'T issue an alarm.

    In any case, I was hoping to find a parameter to supress the alarm output so you could have your cake and eat it too.

    Well I'll be. I think I found it in the new 30i/31i/32i parameter manual. It seems that #1300 bit 1 (NAL) will NOT issue an alarm at the overtravel. Couldn't find the same thing in the 21i manual, though.

    Last edited by dcoupar; 02-23-2010 at 01:59 AM. Reason: Found a parameter!


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    All i know is he stated that he was going past Zero. Zero is not overtravel. Read the post thoroughly and you will see he is describing going past the Zero point and then Hitting the Overtravel, which is correct.As far as the alarm buzzer is concerned it can be disabled but this is done by turning a keep relay off. The downfall to this is you better have a great trustworthy operator because the buzzer will not sound for any alarms. You will see it on the screen but you won't hear the audible. most people will not do this because of saftey reasons, however if you still want to do this then you will need your Supplemental Electrical for the Timers, Keep Relays and not the standard electrical for the machine.



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    Quote Originally Posted by CNCZILLA View Post
    All i know is he stated that he was going past Zero. Zero is not overtravel. Read the post thoroughly and you will see he is describing going past the Zero point and then Hitting the Overtravel, which is correct.As far as the alarm buzzer is concerned it can be disabled but this is done by turning a keep relay off. The downfall to this is you better have a great trustworthy operator because the buzzer will not sound for any alarms. You will see it on the screen but you won't hear the audible. most people will not do this because of saftey reasons, however if you still want to do this then you will need your Supplemental Electrical for the Timers, Keep Relays and not the standard electrical for the machine.

    I've read the post(s) thoroughly. Several times.

    Of course Zero is not overtravel. Machine Zero is usually End of Travel. On a Haas, for example, if you jog X in the + direction it will stop at the + End of Travel (X0). You can jog X in the - direction and it will stop at the - End of Travel (-40 on a 40" travel machine).

    A Fanuc on the other hand will go past End of Travel and go into an alarm state. glenthemann wants to know why it alarms? Why doesn't it just stop at the End of Travel like a Haas or Okuma.

    Alarm buzzer? Who said anything about an alarm buzzer? 99 percent of the Fanuc's I've ever seen or run haven't had an alarm buzzer.



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    Quote Originally Posted by dcoupar View Post
    Of course Zero is not overtravel. Machine Zero is usually End of Travel. On a Haas, for example, if you jog X in the + direction it will stop at the + End of Travel (X0). You can jog X in the - direction and it will stop at the - End of Travel (-40 on a 40" travel machine).

    A Fanuc on the other hand will go past End of Travel and go into an alarm state. glenthemann wants to know why it alarms? Why doesn't it just stop at the End of Travel like a Haas or Okuma.
    Yes, this is exactly what I meant and exactly what I was asking.



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    Default Overtravel Melodramatics

    Quote Originally Posted by dcoupar View Post
    Well I'll be. I think I found it in the new 30i/31i/32i parameter manual. It seems that #1300 bit 1 (NAL) will NOT issue an alarm at the overtravel. Couldn't find the same thing in the 21i manual, though.
    Cheers, I'll give that a whirl tonight!

    DP



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Do all fanuc based machines over travel?

Do all fanuc based machines over travel?