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Viewing 13 posts - 1 through 13 (of 13 total)
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  • #51878

    newbie
    Participant

    I am working in an environment where the process inducts material into its flow intermittantly, as the pieces arrive from other partners in the value stream.  The arrival of material is semi-predictable, but the volume (on a daily basis) is not. 
    Is it reasonable to look at condensing a production window or timeline in order to dampen variability in arrivals?  For example, working a 4 hr shift vs an 8 hr shift in an attempt to have enough material to work at a standard pace / takt time?  I want to fix the Available Work Time and then toggle operators to accomodate variation in volume…am I on the right track?

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    #181425

    DLW
    Participant

    Hi. Your approach MAY be good — IF what you really are needing
    to do is respond to fluctuations in demand as represented by
    whatever is coming into the process (e.g., sales orders).What determines what “pieces arrive from other partners in the
    value stream”? Is that just a polite phrase for a push operation?What you really should strive for is pull. Why is the process seeing
    variable, unpredictable input? What is supplying it?More detail may help.
    DLW – BPEX

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    #181426

    Darth
    Participant

    I agree that pull is certainly preferable to a push environment. If not possible, you can always use a buffer inventory and do a pull off of that. At least the downstream operation will be able to be more predictable and controllable.

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    #181427

    Severino
    Participant

    The idea here is to get everything to work in concert.  You’ve posted this issue here once before and apparently were unsatisfied with the answer.  Can you please clarify why you are receiving your material as a push instead of demanding it as a pull?

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    #181429

    Sridhar Sukumar
    Member

    I agree with Darth.
    having a day’s inventory as buffer would be a great way tackle the issue. However this depends upon the level of value addition your process is doing to the input and working capital scenario of your organization.
     
     

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    #181439

    newbie
    Participant

    Additional Info:
    The process is one in which product is picked up from various retail outlets, delivered to a processing facility (on a fixed transportation schedule) for sortation for downstream delivery.    
    The volume of incoming product is variable across hours in the day, days of the week, and times of year…with daily volume COV running btw 50-65 percent.  It is this daily variability that is causing the most issues…it results in ops staffing the line to run at full capacity to handle these daily and unpredictale surges, allowing for a great deal of idle time and excessive work hours.
    This is a service operation, so building to inventory is not an option.  In addition, the facility must meet strict departure times, so simply extending the workday (ie OT) to handle high volumes is off the table. 
    The idea of structuring the operations to run according to a traditional image of takt time does not appear to be feasible, as the flow of incoming product volume is highly variable and does not appear to be controllable.
    Soooo – my thought was perhaps by shortening the production window (ie Available Work Time) you could build inventory at the front of the process and then when you reach some point of critical mass, staff accordingly, and toggle in additional operators to accomodate unexpected volume during the shift, minimizing idle time while still having the ability to meet demand.  We would not be operating according to traditional takt, but with volume changing significantly and uncontrollably on a daily basis, I thought one way to dampen this sin wave would be to actually build inventory at the front and then standardize the downstream processing….ok.  done.  sorry for the book.  Thoughts?

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    #181445

    Darth
    Participant

    Think of a hospital ED or even a McDs. Demand is variable throughout the day yet over time there is a predictable distribution of “demand”. If they both staffed for max volumes everyone is sitting around. So, they use variable staffing based on the prediction model and in the case of the ED, they use a triaged buffer inventory called a waiting room. Something to think about?

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    #181447

    newbie
    Participant

    That helps a great deal.  As always, thanks Doc!

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    #181453

    Scott
    Member

    Newbie,
    Questions:
    (1) What is COV?
    (2) Your demand model is ambiguous.  You state, “…delivered to a processing facility (on a fixed transportation schedule)…”  This is predictable.  What is not predictable is the demand from your customer that determines how many items will be on the transportation vehicle.  Is your demand a sine wave or a random delta function?  Lunch and breakfast at McD’s is not a random delta function.  Have you tried to make a histogram of demand vs time during the day? 
     

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    #181460

    Sloan
    Participant

    I’ll also remind you that while “product” flows in one direction, information should be flowing also. Is there any way to get some information a day in advance from the sources of the product about expected quantities for the next day? That way you have a day’s notice on how to staff the coming shift. Don’t forget to map the information flow as well as your product flow.
    Just a thought.

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    #181468

    Ron
    Member

    If you want to implement a lean system you should be only producing upstream when the downstream signal allows you to.
    It sounds as if you are attemtping to do what many rookies do..they performa “kaizen” in an area because someone complains about it and miopically focus on that one little area.
    Lean implementation is a site wide initiative and if you were properly using a kanban system what you descibed would never occur.
     

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    #181485

    newbie
    Participant

    We are talking about an existing cell that recieves product directly from the dock operation, manually processes it, and returns it to the dock for transport.   I don’t believe a pull system is applicable here, as there is no upstream or downstream processing, so no WIP, and thus no need for synchronizing multiple process steps.  But I could be wrong…
    Darth’s earlier advice as to using an imperfect predictive demand model and using a triaged buffer stock to absorb demand flucuations appears to be a good fit…but I welcome any advice…thanks!

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    #181494

    Severino
    Participant

    On the delivery side: 

    Is it just one truck making multiple deliveries or several trucks?
    Are some retail outlets more variable than others?  If so can routes be revised such that the net result is more consistent (assuming you have control of the routes)?
    Instead of buffering at your facility could you buffer at your retail outlets so that pick ups only occur once a certain minimum quantity is achieved?  As dumb as it sounds you could combine this with limiting the size of your trucks so that you level load your deliveries.
    If you are not in control of the deliveries (i.e. retail outlets ship when the feel like it via a freight carrier), does package weight correlate to volume of work?  Many freight carriers (such as UPS and FedEx) allow you to see inbound shipment data which might allow you to set appropriate staffing levels.
    On the labor side:

    Can employee hours and breaks be staggered or varied so that the availability of labor matches the variation in supply without the need to increase the number of employees?
    Can a second and/or third shift be added (assuming you only run one shift)?  Taking 6 employees and breaking them into three shifts of two might allow you to eliminate the periods of idle time and ensure that consistent work is being performed while potentially still meeting established turn around times.
    Without understanding the particulars, I don’t know if the above scenarios work for you but I have seen them work in other organizations.

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