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Takt Time Clarification

Six Sigma – iSixSigma Forums Old Forums General Takt Time Clarification

This topic contains 11 replies, has 8 voices, and was last updated by  Sloan 10 years, 9 months ago.

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  • #46579

    irene
    Participant

    I computed the takt time using formula
        takt time = availabe production time / ave daily customer demand
    However, i was told to that it requires a factor of uptime built in to obtain true man/machine balance. Is this correct?
    Per my understanding, you may factor in the uptime built in the computation of cycle time and Cycle time differs from Takt Time.
    In my computation, the Takt Time is slightly higher than the Cycle Time.
    Your response will be very appreciated.
    Thank you.
     

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    #154179

    Bohdan
    Participant

    Takt time is defines as the rate or the rhythm to produce 1 part to meet the custiomer demand.
     
    For example if the customer demad is 642 units per shift
    Total shift time is 8.5 hours (510 minutes)
    Total available time is 460 minutes ( time without the breaks )
    Takt time =( 460 min x 60 Seconds )/ 642 units = 43 seconds per unit
     
    Make sure that you take into account the number of shifts and if you have machine changeover time or other maintenance time you have to reduce the total available time.
     
    Target manpower= total cycle time / takt time
     
    so if you have to assmble your product and you manual cycle time is 8 hours and if the takt time ( customer demand rete per part ) is 2 hours then the
    Required Headcount=8/2=4
    Your product need to flow without building WIP on the floor.
     
    Hope this helps.
    Catherine 
    SSL
     

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    #154186

    irene
    Participant

    Thank you Catherine for your explanation.
    I have to re-do my takt time calculation :-( for the projects that I am doing.
    Have a good day.
     

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    #154188

    Bohdan
    Participant

    I think I had a template for a lean map , you just punch the mubers and it gives you value addes , non value added and takt time

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    #166793

    mcintosh
    Participant

     Hi Catherine,
    can u share the template u had ?
    rgds,
    Tom

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    #175909

    Sumbhat
    Member

    Hi
    I have one confusion and request clarification for the same.
    If the takt time for producing one unit is say 6 minutes( Eg: Available operating time = 600 min and customer demand is 100 units per day), then practically how is it feasible to produce one unit in 6 minutes when actually the entire process ( of 7 subprocesses)to produce a unit takes much longer say 3 hours or 180 minutes?

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    #175916

    Sloan
    Participant

    Don’t confuse takt time with completion time. Completion time is the time it takes to build a single unit. In your example where it takes 180 minutes to build a single unit, your “assembly line” would be 180 minutes long and units would be spaced six minutes apart along the line. A finished unit would exit the line every six minutes and there would be 30 units along the line in various stages of completion (180/6).

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    #175917

    Sloan
    Participant

    Don’t confuse takt time with completion time. Completion time is the time it takes to build a single unit. In your example where it takes 180 minutes to build a single unit, your “assembly line” would be 180 minutes long and units would be spaced six minutes apart along the line. A finished unit would exit the line every six minutes and there would be 30 units along the line in various stages of completion (180/6).

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    #175918

    DLW
    Participant

    Hello,
    Your question is fundamental to the classic struggle of capacity vs.
    demand. Your Takt time interpretation is correct, and it reflects
    external customer demand. Your example of 180 minutes is total
    PROCESSING time, or work content, which is an internal parameter.
    What we strive to do is to have our CYCLE time equal or beat Takt.
    That is cycle time of the system: how often one “unit” is produced
    and ready to be sent on to the customer. When processing time
    exceeds desired cycle time, we have a couple choices: 1. reduce
    processing time (automation, efficiencies, DFSS/DFMA, etc.; or 2.
    apply more resources.
    In your example, processing time is 30 x desired cycle time, so
    odds are not good that it can be reduced enough in the short
    term. That means additional resources: machines, operators, cells,
    parallel lines, multiple shifts, etc., whatever. (And of course there is
    the whole issue of balance among the 7 subprocesses.)
    A word of caution: Very often we see terms like Lead Time, Cycle
    Time, and Processing Time used to mean different things. It’s a
    good idea to make sure everyone is clear on the concepts as well as
    the words.

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    #175919

    Ron
    Member

    No that is not correct.
    Many people do not understand the basic concept of takt time. Your equation is absolutely correct text book.
    Uptime etc are used to calculate OEE.
     

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    #175960

    Suma
    Member

    Thanks for the response. However, if the cycle time for each of the subprocesses is say 30 minutes (whereas the total cycle time being 180 minutes for the unit to be produced ) while the takt time is 6 minutes then why do we try and reduce the cycle time to match the takt time as the takt time sets the pace of production right..
    As i am new to these concepts appreciate if any of you could help me understand .

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    #175971

    Sloan
    Participant

    The idea is one piece flow. So you try to reduce you cycle time in your case from 30 minutes by breaking down the subprocesses into smaller pieces that more closely match the takt time. If you were forced to keep your 30 minute subprocesses in tact, one solution to meet takt time would be to set up 5 parallel production lines each with a takt time of 30 minutes (6 X 30 minute subprocesses) in order to meet your overall 6 minute takt time. Now every 30 minutes, 5 finished units come off the lines and that still equals your demand rate.
    That’s just one example. The point is that you need to match your production rate to your demand and to the greatest extent possible, create one piece flow. You only want to create batches when you can’t physically break down your subprocesses small enough to meet the takt time for  one piece flow.

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