Machine stops randomly in the middle of program

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  • Machine stops randomly in the middle of program

    Hello,

    I am a bit new to the CMM world and PCDMIS, so please bear with me. Ever since our IT dept upgraded our PC (Oct 2019) that runs the CMM, we have been having issues with certain programs and even a tip calibration that stop pretty randomly during execution. They don't always stop in the same spots, and sometimes stop more during one run than another. I have found that if I press the stop button then press execute again it will resume the program, but it is fairly tedious to have to sit in front of the machine and babysit it. It seems to only happen to some programs using a particular probe set up and angles. Has anyone run into an issue similar to this? I need some help to figure out the cause and how to fix it.

    Thank you

  • #2
    What probe and force module are you using?
    Maybe your probe is too heavy for your force module?

    Also if you haven't cleaned your scales for a while maybe it is stopping from dirty scales?

    Comment


    • Nuketon12
      Nuketon12 commented
      Editing a comment
      It is using a 4mm tip and 50mm shank. The force module is a Renishaw TP20 ext force (orange/reddish band) We use this same tip setup for many other programs with no issue. The difference with this program is the angles used are A45 B90 and A45 B-90. I do however have another program that uses this same probe setup and angles without issue. I don't think the problem is that it's too heavy, we haven't changed the probe set up and this program has run perfectly for years. I clean the scales with Isopropyl alcohol weekly, so I don't think dirty scales are the issue either.

  • #3
    Try slowing your move speed down in the program when you are using these angles as a workaround ? Your module is probably shot and needs replacing.

    Comment


    • Nuketon12
      Nuketon12 commented
      Editing a comment
      I have slowed it down, that doesn't help. I use these same angles in other programs with the same probe setup without issue. I'm not getting an error message or "air hits". It's quite literally just stopping for no apparent reason.

  • #4
    Yeah you might need a new TP20. Technically, they are only verified for I think 500,000 hits then you are supposed to replace them. I don't know who is counting their hits like that but that is what the manufacturer says.

    Comment


    • Nuketon12
      Nuketon12 commented
      Editing a comment
      I wasn't aware there was a 500k hit limit, but now I know. I will recommend that we buy a new TP20 for posterity, but I really don't think that's the issue since we use the same probe setup, some with the same angles, for many other programs without issue.

    • A-machine-insp
      A-machine-insp commented
      Editing a comment
      HAHA!!! Our TP20s are probably in the tens of millions of hits...

      I don't use the TP20 any more. They ordered a new CMM 2 years ago and I requested the SP25M head on it.

  • #5
    What's interesting is that we use this setup for well over 50 different programs, but I only have issues with the same two. That leads me to believe that it's not the TP20, but something else going on.

    Comment


    • #6
      Are there commands in the code that change any of the parameters in the questionable programs OR in the good programs that would possibly make one program measure differently than the other? i.e. MOVESPEED, TOUCHSPEED, PREHIT, RETRACT, etc. Is it touching the part when it stops? Or is it up in space away from the part when it stops?

      Comment


      • Nuketon12
        Nuketon12 commented
        Editing a comment
        Some commands may vary between programs. I'm not at work at the moment, but I know in one of the questionable ones the movement speed is set to 100 (most are set around this area) and touch speed is set to 2 (default) I believe we set prehit and retract to 0.2 (we usually do for all programs). The questionable set up is for many small parts in one program and we do 5 circles per part. It will stop out in space after it retracts from the previous hit. When I manually press stop and then execute it will move to the next spot on the circle and take the hit. Sometimes it stops again after 1 hit, sometimes it will take 20 or 30 hits before it stops again and everything in between. There is no pattern and it will stop in different places each run.

    • #7
      Have you cleaned the module seat and the seating are of the TP20 with the silly putty provided?

      Comment


      • Nuketon12
        Nuketon12 commented
        Editing a comment
        I do that with all of our TP20's monthly.

    • #8
      Sometimes, when TP20 probes get crashed, those spherical balls on the bottom will become slightly "un-seated". This has happened to me before. I have been able to "save" (get an extra six months or so) out of those probes by doing the following:
      Take a piece of computer paper and put it on a surface plate. Then, take the TP20 in your hand and gently yet firmly press it down onto the paper (magnet side down of course).
      You will physically feel those little balls click back into place. Then, clean the probe with the magnetic putty, then re-calibrate and you're good (hopefully).

      With all of the above being said, those probes do have a life cycle. There are only are rated for so many hits and then they have to be replaced.

      If the spheres are un-seated and are getting triggered by these programs in particular...MAYBE its because of the angles that are being used in this program.
      MAYBE the angles put the probe at a higher deflection ratio then other programs so the issue doesn't present itself there.. but when THESE programs are used..it shows up. Just a thought.
      Last edited by DAN_M; 08-27-2020, 08:15 AM.
      SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

      Comment


      • #9
        If it is ONLY in 2 programs, and 100% random, copy those programs and paste them in a " new " program. This is kind of like re-booting. You never know....

        Comment


        • Nuketon12
          Nuketon12 commented
          Editing a comment
          I tried that and still have the same issue.

      • #10
        Many have suggested it had something to do with the TP20. I took another one from a different set up we hardly ever use and switched it. This one was a STD force, so I had to slow the program down to avoid air hits. It is still stopping randomly even with the newer TP20.

        Comment


        • BKulpa
          BKulpa commented
          Editing a comment
          Try a different TP20 probe body and not just the module. Make sure all connections to the Renishaw electronics are secure.

        • gibsonridge
          gibsonridge commented
          Editing a comment
          this may be way off base but here are my 2 cents,
          is this a large program? i have seen in the past , a pause while running a large program .
          since you upgraded, verify you have enough ram and a good enough processor .
          upgrading these have solved issues for me back in the day.

          just something to check other than the tp200 & tp20

      • #11
        Nuketon12 you say
        movement speed is set to 100 (most are set around this area) and touch speed is set to 2 (default) I believe we set prehit and retract to 0.2 (we usually do for all programs).
        Can you confirm the following.
        1. Are you working in % or absolute speeds (you can check this by hitting F5 and looking on the PART/MACHINE tab)?
        2. Are you working in Inches or millimetres?
        3. Are your circles auto-features with circular moves turned on or are they measured circles?
        If you are working in % then you need to calculate what 2% of your machine's top speed is to work out a mm/sec value. The touch speed for a TP20 should be between 0.5 and 5 mm/sec. The default of 2 is for when you are working in absolute speeds i.e. 2mm/sec. Similarly, if you are working in inches a pre-hit & retract value of 0.2 is fine whereas 0.2 mm would be far too small a value. The default pre-hit / retract is 0.1" or 2.54mm. My final thought regarding circular moves is a bit of a long shot but it might be that if you are on an old machine or have a controller that does not fully support circular moves it could be that it is having trouble calculating the movement path and this could be why it stops. Related to this but again, an even longer shot, is if the communication between the PC and the controller is being interrupted in any way. A common culprit in those cases is antivirus software or a faulty cable / bad connection.
        Neil Challinor
        PC-DMIS Product Owner

        T: +44 870 446 2667 (Hexagon UK office)
        E: [email protected]

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