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Manufacturing - Tracking

Discussion in 'Embedded' started by eeboy, Feb 18, 2011.

  1. eeboy

    eeboy Guest

    I work for a small manufacturer. We ship a product with several differen
    PCB assemblies. We've never had a good system to track exactly what goe
    out the door to each customer. I am in the process of rectifying this an
    wanted to see what others do. At a minimum I want to relate the PC
    revision and PCB assembly revision as well as the firmware revision back t
    a serial number. I'd like to get even more detailed, but I am not sure a
    what point it is too much data/work. I thought of tracking the lot that th
    assembly came from and perhaps even trace this back to the reel of
    particular component. It would be nice to say "we have a problem wit
    component x from lot y... how many boards are affected?". At this point
    can see it becoming quite complex because we never use an entire reel o
    one particular component on a given lot of PCB assemblies. For example,
    capacitor from a single reel might be used in several different PC
    assembly lots (POs). Moreover, since we only assemble the final produc
    here and our PCB assemblies are provided turnkey this means we would hav
    to rely on our contract manufacturer to provide this data.

    So, I was just curious how other manufacturers tracked their products an
    if anyone got to that level of detail.
     
    eeboy, Feb 18, 2011
    #1
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  2. eeboy

    Tim Wescott Guest

    Why are you tracking? That'll tell you a lot about what you want to track.

    Aerospace/defense sort of suppliers do everything by revision level: if
    you bump the rev of a lower-level part, then you have to bump the rev of
    the assembly. Then all you have to know is that thus-and-so serial
    number was at rev level such-and-such, and you know the rev levels of
    all the parts.

    That can get onerous, but at least you _know_, and if necessary you can
    duplicate a system.

    --

    Tim Wescott
    Wescott Design Services
    http://www.wescottdesign.com

    Do you need to implement control loops in software?
    "Applied Control Theory for Embedded Systems" was written for you.
    See details at http://www.wescottdesign.com/actfes/actfes.html
     
    Tim Wescott, Feb 18, 2011
    #2
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  3. eeboy

    eeboy Guest

    Why are you tracking? That'll tell you a lot about what you want t
    track.

    Part of the tracking is so that when they call up with a technical questio
    we already have a background on what PCB assemblies and what rev firmwar
    is in the widget.

    However, it would be nice to track to the component level. For instance, w
    recently had a board where a particular capacitor failed. If I could kno
    what lot of PCB assemblies these were coming from or what lot of component
    they came from I could quickly isolate the problem. For instance if all th
    bad caps were spread across several assembly lots but were all from th
    same reel (one reel of this component spanned these assembly lots) I coul
    start to draw some conclusions about why the part is failing. Perhaps I a
    trying to do too much. I would *hope* I don't have to trace failures tha
    often.
     
    eeboy, Feb 18, 2011
    #3
  4. The above is what we do. The bare PCB is treated as another component,
    so if it changes significantly it's revision level is automatically
    incorporated in that of the assembly, Each serial number is linked to
    the lot number, and the lot is defined by a list of assembly part
    numbers and revision levels.
    For general manufacturing I think this is too expensive to do for just
    the reasons you give.

    We do incorporate a "job number" in purchase orders, so in principle we
    can establish the boards at risk. I.e., all those made after the arrival
    of the PO that contain the part. I can't see a practical way to do
    anything more. A reel can last a long time. Assemblers lose a few parts
    here and there, or open the new reel instead of the old one.
     
    John Devereux, Feb 18, 2011
    #4
  5. eeboy

    Dennis Guest


    In my limited experience failures due to a particular part (where it is not
    a design issue) can be tracked by batch. IE a dud batch of caps / ICs etc
    are used in a production run. Keep a s/m range for each batch run.
     
    Dennis, Feb 18, 2011
    #5
  6. eeboy

    Joe Chisolm Guest

    Take a look at OpenERP. Might do what you want.

    http://www.openerp.com/
     
    Joe Chisolm, Feb 18, 2011
    #6
  7. eeboy

    Dennis Guest

    Whatever you do use a proper database system and not a spread sheet. I
    shudder when I hear someone complain they can only get 64K lines in
    Excel - that is at least 10x past where they should have done something
    else.

    I once worked on a project where they had data on hundreds of parts in a
    spread sheet. The part had a serial number and the subassemblies had
    version and serial numbers. They were trying to correlate burn in test
    failures to see if there was some common factor by hand. I exported the
    data in csv format and read it into a MySql (because it was free) data
    base and then did SQL queries to get the data a lot faster.

    I realize that not everyone is a data base expert but there are some
    that are fairly easy to use - particularly if you don't need industrial
    strength performance and recovery features.
     
    Dennis, Feb 18, 2011
    #7
  8. We use ICIM and have a module that can 'marry' serial numbers
    together. Actually, a parent number (say - the mother board) could get
    a cflash and memory stick, and 1 or more PC-104 daughter bds.
    'attached' to it. The serial number database is altered, and scanning
    any of those numbers afterwards will bring up ALL the asssociated
    serial numbers. Internally or if one come back in for repair. Though,
    several of us feel we shouldn't serialize mem sticks and cflash or
    basically any 3rd party items we re-sell. We do not serialize
    cables,hardware mounting kits, etc. either.

    But every 'top level' assembly with a serial number pulled for an
    order gets scanned in shipping and 'attached' to the SO and other
    shipping paperwork.

    Basically, ask yourself why you are tracking and what does the
    customer expect. Try not to track accessories, 'throw-away' items or
    items that would be re-sent back to your vendor. As for internal
    tracking, we use 'work order numbers' which share part of the same
    label with the serial number and the text board or product 'name'. So,
    internally, we can research the WO if a problem is found in testing,
    or, rarely, by a customer failure and take appropriate action
    (contacting other customers, reworking/scrapping product still in
    stock, etc.) Those situations are rare.

    Internal tracking is basically for 2 reasons related to inventory
    control and process control/quality. External tracking is more for
    warranty duration on returned items, to help with quality/process
    problems on occasion, and maybe just to satisfy a customer's
    expectations.
     
    1 Lucky Texan, Feb 19, 2011
    #8
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