Production scheduling

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    Black Belt Boy

    Can sometime help me in trying to analyze production scheduling.
    Currently we use a 3 week forecast to schedule, but we have twice weekly forecast updates that then are used to “change” the schedule. This leads to adding or dropping out orders that may or may not be getting set up for production. I’ve looked at the past years production on the parts and found the average and standard deviations of production month to month.
    They are wanting a “standard” schedule they can run to and be able to schedule work without deviating daily or hourly.
    I’ve asked them to start tracking the schedule on Monday and separately track daily changes in schedule, but do not change the original schedule.  Because there are two matching parts that come together at final assembly, the “mis-matching” of parts is a major issue (a weeks worth of production can’t be ran due to mis-matches).
    Am I on the right path?



    Basically yes, but do you have a ‘frozen’ period ? Or your weekly forecast update can change also daily prodution ? If it change also daily production, I think you could set up a little ‘safety stock’ .
    Further, if your schedule is daily/weekly why you calculated stdev and means monthly ? There isn’t a risk do not capture daily/weekly variations ?
    Rgs, Peppe



    You might be on the right track, but it depends on your Sales/Business model.
    Are you building to order or to stock?
    If you are building to Stock, then your are on the right track as long as you have established stocking plans to address the expected sales forecasts for a given SKU.
    If you are building to order, as long as you have a cycle time less than the expected delivery window + the schedule window for a “frozen period” in your scheduling system you should be OK.
    We operate several Business units on a similar plan, We schedule weekly and freeze the weekly schedule, we plot this against an ideal “buffer inventory” for sales purposes. If we sell more than we expect within the week we up the following weeks schedule which is frozen once released, to compensate, knowing we have WIP in place to replenish what we have sold.(our cycletimes range from 3 to 11 days).
    While this method is by NO MEANS perfect or completly lean, it does serve our current circumstances and has allowed for better Customer Service , increased sales and reduced inventories, all goals we had when we started.
    Hope this helps,


    Black Belt Boy

    Thanks for the info.
    It was my plan was to “freeze” the schedule on Monday, but track the changes and adjust by adding the “carryover” onto the next week’s schedule. Tracking the changes by week can help predict the safety stock needed. We now change our daily planning based on these changes. I’ve shown that our overall volume changes no more than 10% weekly, but the mix changes (40+ part combinations) weekly. I’ve also shown we have one week supply of mis-matched unsaleable product.


    Black Belt Boy

    Currently we do not have a “frozen” schedule. It is free to change hourly if needed. Hence we chase our tails.
    Our system is not able to go back in time to see shipments by week, but only monthly totals. No one keeps that information nor do they keep a schedule vs. shipment history.
    I believe by freezing a schedule we can at least see where the variation is and get some data to how much, when and why it changes.

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