Polar 137 EMC

Discussion in 'Cutters and Trimmers' started by nadg63, Feb 25, 2019.

  1. nadg63

    nadg63 Member

    Joined:
    Dec 2014
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    Location:
    Australia
    Have a couple of issues regularly coming up with the Polar 137 EMC that I operate!

    - Scale Pulses Missing

    - Position Not Achieved

    Any hints as to where to be looking for the source of these!? (reader cable!?)

    Thanks in advance.
     

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  2. petermif

    petermif Member

    Joined:
    Feb 2013
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    Location:
    MALTA (EUROPE)
    Hi,

    I've had similar issues on my Polar 92 EM-Monitor....they tend to be related to the brake or motor on the back gauge.

    Scale Pulses Missing means that you issued a command for the backgauge to move and the computer did not see any input from the Linear Measurement System (or rotary encoder depending on what your machine has) within a given time.
    Given that you also get Position Not Achieved errors I'd check the following:
    1) the brake may be is sticking or not releasing in time. The brake on my machine is manufactured by Lenze and there is a mechanical adjustment which involves measuring a small gap between brake rotor and stator.
    2) the drive motor not receiving enough power and therefore not moving fast enough (I had exactly this problem once and it was a contactor which drives the back gauge motor having one contact burned out and not supplying the 3 phases correctly).
    3) the DC Power supply not supplying enough juice to de-energise the brake quickly!
    If you're electrically qualified and know exactly what you're doing you can check this. I'd start with the power supply to the brake; check the +24v and check that it can handle the load when the brake de-energises to move. Next I'd check the main contactors (3 PHASE MAINS SUPPLY HERE SO BE CAREFUL) on the MCM unit which is responsible for the back gauge motor drive.

    Finally there are other possibilities like the cable from the LMS (which travels backwards & forwards with the backgauge) getting pulled or frayed etc. so I'd have a good look underneath the table at the back of the machine.
    There are a few more possibilities but they become more complex and costly so i'd chase these down first.......good luck!
     
  3. nadg63

    nadg63 Member

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    Thanks for that Petermif.

    As a follow up here's the latest:

    Had the engineers playing around with the brake on Monday, since then no more 'Position Not Achieved' issue - yay! (and during operation I've not had the 'Scale Pulses Missing' issue either), BUT there is still something going on we are trying to pinpoint.

    Here's the scenario, first thing in the morning I run a programme of '120 -U-turn - 1320 - U-turn' for oiling the back gauge. It's only during this operation that the 'Scale Pulses Missing' fault rears its ugly head! The gauge can be moving backwards and forwards for up to 10mins (though that period can vary and be a few seconds), then all of a sudden you can see the gauge dramatically slow down, stop, then flash up the 'Pulses' message!? I know the obvious answer is to not run the oiling prog BUT it has run it without issue for years previously. :)
     
  4. petermif

    petermif Member

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    Hi nadg63,

    Glad you 'Position Not achieved' error is gone.

    Scale Pulses error is more challenging. The program you run every morning (good idea btw!) moves the backgauge along it entire length so what crossed my mind is this. In practice you rarely cut at the extreme edges and perhaps moving back to 1320 stretches the LMS cable so perhaps if this cable is broken internally, when stretched to this extent, the stream of pulses from the LMS goes missing, this will cause the error. I've seen cables break internally and the fault is intermittent and can be a ***** to find. On my machine this cable is a shielded cable with metal DIN connectors and can be replaced quite easily so perhaps this could be a quick and easy fix. I strongly suggest you get the proper part from POLAR as the type of wire used for this cable should be a special high flexibility type. Also note carefully (take photos) of the cable routing and anchoring points and don't improvise!! This is where i would start as the other possibilities involve the either the LMS system itself or the PI board (or both) and those are expensive and must be done by Polar techs as they will impact the sizing, accuracy and repeatability. Good luck.
     
  5. nadg63

    nadg63 Member

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    Location:
    Australia
    Cheers Petermif,

    Re the stopping, it has no preferred stopping point, it can be anywhere along the travel of the back-gauge, just to confuse the issue!

    We get a sparky in that specialises in printing equipment so I'll show him your replies, (once we are able to get him on-site, busy man!), and see what he comes up with.

    Once again, thank you very much for your input.
     

  6. petermif

    petermif Member

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    Messages:
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    Location:
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    Hi nadg63,

    Just one word of warning. You need special equipment and software (which only POLAR have) to set up the LMS system and get the sizing right so tread carefully!!

    Peter
     
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