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Rework loops in Value Stream Maps

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  • #38876

    TAD
    Member

    I am working on a value stream map that has a highly significant rework loop.  How are those loops typically included in the layout of the value stream?  Are they placed above the critical pathway?  What has worked best for you?

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    #117131

    JPK
    Participant

    Tad,
    I’m making the assumption that you’re following the approach described in Rother and Shooks book “Learning to See”.
    There are different approaches to doing this.  Your goal should be to expose the source of waste so that you can minimize or eliminate it.  You should also consider the timeframe of when the product is reworked as well as the location of the rework relative to the point of manufacture.
    The first approach is using the data boxes for a process step only to show the yield loss and/or defect rate.  In my experience, this works best when the product is being fixed shortly after the defect has been created.  The data should focus attention on that portion of the process.  The data box also can show the amount of “rework” inventory. 
    The second approach would show material and information flow out of the step generating the defects to the process that fixes them.  I think that this is what you’re referencing about placing it above the critical path; in this instance conforming product flows to the next process step and non-conforming product flows to the rework location.  This seems to work better in visualizing the problem when movement occurs and storage time results, especially if the re-work is moved, stored at a warehouse, moved again to the rework area and then brought back into your critical path.  The information flows to handle the re-work should also be outlined as well, especially if the organization “schedules” the rework.  One possible downside to this approach is that you have to look backwards through the value stream map to find where the rework is created.  The improvement effort needs to focus on the defect generation.
    I’ve seen a third approach used (wouldn’t use it personally but wanted to mention it for a comparison) which is to create a step called rework and insert it above your critical path.  It highlights the problem more than the first approach but doesn’t capture as much detail as the second approach. 
    If you’d like to discuss this in more detail in person with respect to your current situation, please post back your email address and I’ll send you my contact info.
    Regards,
    Phil

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    #117358

    Rick M
    Member

    Good ideas already. What is rework really? How about thinking of it as inventory stalled and then needing a process to convert back intot he value stream process? So, one might want to show the amount in rework as the triangle inventory with hours on hand metric as non value and, if substantial to convert, add a step as non value to convert back into the process.

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    #117360

    Dayton
    Member

    Rick M,
    I’d rather guess what the “M” stands for.
    Vinny

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    #117627

    Scott
    Member

    I hope the ideas helped. Vinny – not sure your question. You may contact me at [email protected]

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    #117635

    Dayton
    Member

    Nope.  There was no question.  Sorry.
     
    I just thought I recognized the beginning of a familiar rant that a past colleague of mine used in routinely beating me into submission.  But his email would have an xxx.edu address versus an sbcglobal.net address and he would not have stopped posting after a single paragraph. 
     
    You’re not a big loud obnoxious redheaded Cornell guy that thinks management science and operations research are synonymous, are you?
     
    What is rework really?  Think of it as….      
    What is factory automation really?  Think of it as….    
    What is a Markov analysis really?  Think of it as….        
    What is a time motion study really?   Think of it as….     
    What is organizational engineering really?   Think of it as….
    What is the paperless factory really?   Think of it as….
     
    Well you get the point.    Hours upon hours of my life wasted almost responding to rhetorical questions he asked only to have him blurt out a pre-formulated answer first trying to appear a gifted Socratic instructor…    He was a real pain in the butt.     I think I’ll give him a call.  
     Vinny 

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    #117637

    Darth
    Participant

    Vinny, you really need to get over it.  You have graduated and are successful.  You are almost grown up now.  You don’t need to dwell in the past.  You should call your tormentor and tell him how you feel.  Move on.  It is so sad when the brightest and most rigorous carry such baggage.  Unfortunately, Dr. Barry is an opthamologist otherwise I would have you book the next Bench appointment.  Possibly a visit to some power vortex in Sedona will draw out all that negative energy and put you on the path to healing.  I will send you some Prozac samples to go along with the Cialis I recently sent.  Hope they help. 
    Your Friend,
    Dr. Shirley

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    #117639

    Markert
    Participant

    Darth:See; I knew that when you confused one of my simple posts for
    Vinny’s insightful, rambling, stepwise artwork, it would put him into an
    emotional tail spin. Sorrrrrrrrrry, Vinny…….but in case, just say no to Dr.
    Barry’s Stun-gun treatment.

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    #117640

    Markert
    Participant

    Darth:See; I knew that when you confused one of my simple posts for
    Vinny’s insightful, rambling, stepwise artwork, it would put him into an
    emotional tail spin. Sorrrrrrrrrry, Vinny…….but in case, just say no to Dr.
    Barry’s Stun-gun treatment.

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    #117641

    Darth
    Participant

    Phil, it first starts with repeating yourself.  Then comes the drooling.  Next the incontinence.  It’s not long now. 
    Don’t worry about Vinny, he is a tough guy and will get through it.  I have offered to let him produce the instructional videos for the Dr. Harry SDMS starring BOAS.  That should pull him out of his depression.  I can tell that cheered him up because all he asked was, “Can I wear my tie dyed t-shirts, sandals and favorite cranial adornment?”  He will be OK with our continued support.

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    #117643

    Dayton
    Member

    Thanks Drs. Shirley and Phil.   I feel much better now.    But please send the promised meds…
     
    Now let’s get back on the Six Sigma stuff.   Sorry to have distracted the forum again.   
     
    There exists a paper from The Annals of Statistics from the Institute of Mathematical Statistics of the University of Copenhagen that describes the connection of log-linear interaction models and Markov fields in developing graphical hierarchical modeling multidimensional contingency tables and these models include decomposable models.
     
    And to the point, this statistical treatment of decomposable models could provide for an elegant graphical depiction of the model improving the ability of the reader to understand the model and it’s cyclic subgroup(s) – moving away from dependence on the just-a-tad-clumsy Goodman’s algorithm.  
     
    Has anyone effectively used this approach in projects/studies/research and what have been the receptiveness, comprehension and concerns regarding its use?   I ask due to the absolute graphical clarity provided via this path, yet my lack of recognition of its application beyond academic esotery is giving me concern that I might spend more time explaining and rationalizing the path taken than the clarity of depiction is worth.
     
    I’d appreciate your thoughts – although I’m about this close to going with it anyway just to see the group’s dynamics in scrambling to catch up.
     
    Vinny    

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    #117644

    Darth
    Participant

    IT’S A MIRACLE!!! HE’S CURED!!!!! HE’S BACK RAMBLING ABOUT ESOTERIC CRAP NOBODY UNDERSTANDS OR CARES ABOUT!!! WELCOME BACK KOTTER, I MEAN VINNY.

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    #117647

    Dayton
    Member

    I’m beginning to think it’s a darn good thing we don’t work together, as problems would arise – not the least of which would be that we wouldn’t get anything done.
     
    But, suppose you had opportunity to apply a graphical decomposable modeling technique to genetic network analysis (as in real DNA) and you believed the only well-documented prior usage of this approach had been done by the University of Munich and Graz University of Technology in a study sponsored by Siemens AG which appears to be highly a highly convoluted and somewhat contrived treatise on childhood acute lymphoblastic leukemia would you go with the graphical modeling with the understanding that you were presenting your findings to three separate somewhat technical populations simultaneously, bio-statisticians, geneticists (some PhD, some MD), and commercial operations representatives?   
     
    None of which would inherently understand the decomposable graphical modeling, but all would/should understand salient points made using the graphics.   I don’t want to attempt enhanced clarity only to muddy the waters.
     
    I’d tell you more about the study but I’d have to kill myself – sort of a CIA operative’s reciprocal response.
     Vinny

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    #117648

    Darth
    Participant

    Ok, now I got it.  Sounds good.  Go ahead and continue your research and fill us in on the highlights as they become apparent.

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    #117650

    Dayton
    Member

    Actually it’s done.  I present on the morrow.   After numerous dry runs with various facet subject matter experts and stakeholders it goes like it is.   Oddly enough the few that asked about the methodology asked only out of curiosity and offline at that.   
     
    I can again only conclude from our “hit it hard” internal subject matter expert dry-runs that scientists desire the absence of Phil’s stressful cognitive dissonance, biostatisticians want only to know total population, sample size, selected tests, and see many numbers and associated Greek symbols, and our commercial guys are completely enthralled with all of the pretty charts and graphical models – with some confusion as to when the “models” were finally going to get there.
     
    I thought while the countdown is on I’d get an additional statistics concentrated sounding board by running the concept by the forum.   I appreciate your knowledgeable advice to “Go for it”.   It’s nice to have a well educated albeit anonymous group of quantitatively inclined professionals from which to occasionally seek counsel.     
     
    This way when my CEO, who I have a great dealt of respect for even though his doctorate is from an Ivy League school and you occasionally tire of watching his marvelous class ring wave around in meetings (his ring appears to have a self-contained energy source – I’m suspecting it’s a tiny prototypical nuclear fusion plant), grabs me by the lapels and screams “It’s all your fault dipstick, where did you get those freaking tinker toy looking graphical models????” I can say, “Well, Sir, this guy Darth who posts on an anonymous technical Internet forum on which I spend an inordinate amount of time and who claims to have a PhD in something from somewhere and teaches advanced Motorola based quality programs to failing commercial entities told me to ‘Go for it’ so I did.”
     
    It’s a good thing my kids like Burger King – soon they’ll be able to yell back to the fry area “Hey Dad, can you put some onion rings in there too?”….. 
     Vinny

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    #117651

    Markert
    Participant

    Vinny;
    That smokeless tobacco company Copenhagen has a University too? I didn’t realize that; looks like they are positioning themselves for the adult learner market once these states lawsuits kill the industry.
    Maybe we should contact them to do some Sxxt Sigma on-line training in addition to whatever else they are ramping up with.
    Anyhow, running this topic by the forum the day before your presentation; you sure know how to make your hours really count; anonymous groups of mouth-breathers do really provide insight into subject matters like the one you’ve proposed here at T minus 24 hours.
    Here’s your golden parachute in the event that your blaming Darth for the misfortune doesn’t work; ask Mrs. Dr. Vinny to spend a few minutes modifying one of the kid’s old sock puppets, stuffed animals, SpongeBob’s, etc. with a couple of the CEO’s characteristics. (Elvis sideburns, long nose hairs, bad plad sportcoat, big honkin Ivy League class ring, or so on.) Bring a couple of them along for effect.
    If the presentation tanks, bring out CEO Dr. Furby and finish it using CEO Dr. Furby as primary presenter. At least then you’ll have some administrative leave for mental health to fall back on…..and it will make you an urban legend around the corporate campus.
    Wishing you excellence in your results, a great presentation, and hoping that you have a large enough briefcase for your tools, slides and CEO Dr. Furby and his friends.   

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    #117655

    Dayton
    Member

    Thanks for the thoughts.   Actually Ms. Dr. Vinny had already begun what few physio-modifications are necessary.   I don’t really need a Dr. Furby – I always present as Elvis.  Mutton chops et al. But sort of a mid-range Elvis, where the eyes are beginning to bag and the complexion going sallow but I have not (yet) gone to expanda-waist leather jumpsuits and plus sized capes..   And my kids usually only show up after the presentations are over to shag extra Diet Cokes and chocolate chip cookies.   A good presentation can keep them in snacks for weeks. 
     
    No blame distributed anywhere, the upside’s mine and the downside’s mine.  But, it will go well.  Science and applied statistics will win out.  Plus I’ve got all of those colorful graphics and cute models.  
     
    I didn’t expect response, mostly just enjoyed the cathartic mind numbing rambling – but you understand that better than most.   I did think I’d offer such a compelling story that Darth and you couldn’t resist jumping in with advanced statistical guidance.  I was partly correct with the good advice to “Go for it” and to use embellished surrogate hand puppetry – as if I hadn’t already thought of that!!   
     
     Vinny

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