iSixSigma

Lead time vs. Throughput

Six Sigma – iSixSigma Forums Old Forums General Lead time vs. Throughput

Viewing 24 posts - 1 through 24 (of 24 total)
  • Author
    Posts
  • #39982

    Rachel Buszka
    Participant

    What is the difference between lead time and throughput?
    Which is a better indicator of process improvement?

    0
    #122948

    RonK
    Member

    Lead time usually is measured in days and throughput has no sense if we know the quanty of resources used to obtain a throughput.
    And when I meen resources I include the japanesse organizations worker’s own time, their personnal life timetables robered from these organizations.
    The First error: Compare Lead time with Productive value added time process.
    How much it cost a part stored 4 hours within the process? A Lean “expert” never could ask me this.

    0
    #122951

    jediblackbelt
    Participant

    Rachel –
    On a more micro (Cell) level I have looked at Lead time as the time it takes to get a piece from start to finish.  So I would tag a piece at the beginning of the process and then time it until that piece ends up in the ship container as a completed part. 
    The throughput I have always looked at as how many pieces / time period you are making.  So you may be running the parts at 60 pieces per hour and have a lead time of 10 minutes.  So you could go back to Littles Law (I believe) and show you have 10 pieces of WIP in the cell.  WIP = Lead time / throughput.
    Just how I have used it.  Not saying that it is 100% correct, but that is how I have always interpreted the Law.  Which gets you to the point of showing how a one piece flow is the most efficient method to reduce lead time.
     

    0
    #123207

    gurumanuf
    Participant

    In a simple way;
    Lead time is the commitment to deliver final product to your customer. Through put time is the sum of all of your product individual process times accounting for value added and non-value added activities. For example a company may have a lead time of 7 days to deliver a product to the customer and a through put time of only 8 hrs.
    Through put time is the metric you should use for continuous improvement focusing in reducing/eliminating the nva activities of your process.
     
     

    0
    #123266

    DANG Dinh Cung
    Participant

    Good morning,Following are definitions from APICS Dictionary.LEAD TIME : 1) A span of time required to perform a process (or series of operations). 2) In a logistics contexte, the time between recognition of the need for an order and the receipt of goods. Individual components of lead time can include order preparation time, queue time, processing time, move or transportation time, and receiving and inspection time. Sy: total lead time.THROUGHPUT TIME : Syn: Cycle time.CYCLE TIME : 1) In idnstrial engineering, the time between completion of two discrete units of production. For example, the cycle time of motors assemble at a rate of 120 per hour would be 30 seconds. 2) In material management, it refers to the lenght of time from when material enters a production facility until it exits. Syn : throughput time.Regards,DANG Dinh Cung
    [email protected]

    0
    #123267

    KKN
    Participant

    Response to “Which is a better indicator of process improvement?”It depends on the customer of the process/project. If you are working a project where your customer is external to the organization, generally, lead time is what they feel and see. If internal, and focused on process improvement, cycle time is key.

    0
    #123467

    DRB
    Participant

    Lead Time – the time taken to produce an individual product in the process.
    Throughput – the total time to produce a set of the same product ( which is to be maintained)
    Both these indicators are related to the situation in which the product is being manufactured. There many be bottlenecks, defects, man-made errors, etc which effect the lead time & the throughput.

    0
    #123580

    Eddie C. Au
    Participant

    Throughput is Cycle time.  Cycle time is a subset of Lead Time.  Cycle time may equals to, less or more than Takt Time.  Cycle time can be expressed in unit of a single motion, activity, process or department.  Cycle time is almost like the Standard Time if you’re talking about a relatively small unit such as an activity. 
    From a Lean pt. of view, we should improve Lead time because it consists non-value added time.  From a Six Sigma pt. of view, we come to the same conclusion because of the substantial savings from cutting the Lead Time.  This confirmation is one of the strength of Lean Six Sigma Methodology.

    0
    #142754

    Pedro Vargas
    Participant

    Is it correct to state:
    The sum of (n) all Cycle Times equals to Total Lead Time ?
    Are the non-value added activities included as well as the NVA but necessary?
    please help clarify this question.  Thx

    0
    #173779

    NEERAJ SHARMA
    Participant

    difference between lead time & throughput time

    0
    #173785

    Michael Mead
    Participant

    Hello.  Is that a question or were you starting to write an answer?
    The best definitions given above are from DANG Dinh Cung. Please check it.

    0
    #174576

    Dhanasekar K
    Participant

    thanks for nice information

    0
    #175323

    Surendran
    Member

    Dear sir,
    What diffrence between six sigma Vs lean six sigma
    By,
    A.Surendran

    0
    #175325

    Plastic
    Participant

    4 letters….
    Has to be harder questions here somewhere…

    0
    #175328

    keyes
    Participant

    Very pithy reply……
    Try this folks………
    Lean eliminates waste/time and increases velocity.
    Six Sigma reduces variability in all processes.
    USe of both simultaneously is very powerful.
    Enjoy.

    0
    #175329

    Robert S
    Member

    Oh…and here I thought LSS was SS without the fluff.

    0
    #175338

    Mike Carnell
    Participant

    Greg,
    Two issues with your response.
    Lean reduces waste for the most part. I have never seen waste completely eliminated. Probably picking nits on that one.
    “Six Sigma reduces variability in all processes.” We will skip the symantics around “all” processes. Six Sigma was originally billed as a “breakthrough” methodology. If you go to the definitions established by Juran in 1964 “Managerial Breakthrough” he distinguishes between breakthrough and control. Control is by definition a “lack of change” i.e. something that you can monitor and adjust on a control chart – maintaining status quo. Breakthrough on the other hand is dynamic change. More of an optimization type philosophy very much in line with Taguchi and the idea of operationg to a target. Of course there is the maintenance of the target once it is understood and that becomes a control issue.
    The point being is that Six Sigma was set up as a beakthrough methodology. A way to leapfrog to a better competitive position rather than going through the pain and wasting time on incremental improvement. As much as people like to face of SS and TPS – even TPS has both types of methodologies in it.
    To some extent you are correct. Today people treat SS as variation reduction because a large number of people were raised on focusing on variation reduction so if you change the SS focus it is more palatable to them. It becomes an extention of what they have always done – put a control chart on it and wait and see what happens. Look at all the focus that is on this forum on control charts or lack of change. It is other tools such as hypothesis testing that get you into a breakthrough mode. It is almost a difference in passive CI versus Active CI. The lage effect that was seen in the initial SS deployments was the result of the focus being placed on breafthrough – finding a more optimal place to operate your process.
    All that said the basic split between the two isn’t that simple. Most would throw breaking a bottle neck into a lean catagory to use your words because it “increases velocity.” Very simply if there are technical process issues that cause something to be a bottleneck you will find very frequently lean does not have the analytical tools to resolve the issues and break the bottleneck.
    It is the combination of three – waste reduction, optimization and variation reduction that is most powerful.
    Just my opinion.

    0
    #178971

    SPSingh
    Member

    Kindly give me the definition, concept and formula for calculating the throughput time and relation between lead time and throughput time
    Thanking you,
    warm regards
    SP Singh

    0
    #178974

    Six Sigma Shooter
    Member

    Mike,
    I may have taken your post wrong, but in response to your comment, “something that you can monitor and adjust on a control chart – maintaining status quo.”  If we relegate control charts to just monitoring and control, we miss the real power of the tool.  If we use them as a tool to reduce the common cause variation once we have stability and control, we have tremendous power to achieve the desired results of the Taguchi Loss Function and achieve true breakthrough achievement in process improvements. 
    Don Wheeler and Henry Neave wrote a good article on this, “Shewhart’s Charts and the Probability Approach”
    (http://www.spcpress.com/pdf/Wheeler_Neave.pdf).
    “While a control chart may be used for process monitoring, the point is that monitoring is only a minor part of what control charts can do, rather than being all that they can do. The probability approach generally relegates the control chart to the role of a mere monitoring procedure after the process is presumed, by some undefined means or another, to find itself in a satisfactory state. The control chart’s function is perceived to be an early warning device of when the process moves away from this supposedly satisfactory state.
    The crucial difference between Shewhart’s work and the probability approach is that his work was developed in the context, and with the purpose, of process improvement as opposed to process monitoring. From his perspective, a major purpose for creating the control chart was to provide help to get the process into a “satisfactory state” which one might then be content to monitor (if not persuaded by arguments for the need of continual improvement).
    This difference is far more important than some might at first appreciate. It gets right to the heart of the divide between the main approaches to the whole quality issue. On the one hand, we have approaches which regard quality merely in terms of conformance to requirements, meeting specifications, Zero Defects. On the other hand, we have Deming’s demand for continual improvement—a never-ending fight to reduce variation. The probability approach can only cope with the former.
    Shewhart’s own work was inspired by the need for the latter.”
    Shooter
      

    0
    #178984

    Mike Carnell
    Participant

    Shooter,
    You went a long way back for that one.
    The definitions I used for control was fron Juran in his book Managerial Breakthrough. It was a definition of control not necessarily control charts. The important part that he brought out in the book was the difference between control and breakthrough.
    Now control charts. I have seen it on here and I would be willing to bet you have as well. Control charts have been taught for years that you cannot do anything about common cause variation which I believe is nonsense. The way I have always approached SS is that you use the methoidology to identify what the target should be and to reduce common cause. Because of the way people were trained for years on Control Charts and to avoid the discussion about not being able to do anything about common cause we would diagram something like yield on a time series analysis and then draw in what the “Cycle Time reduction people used to call entitlement. anything above entitlement you leave to the traditional firefighting. Below entitlement was the inherent process capability as it exists, inherent supplier capability as it exists and design (which never goes above entitlement – special causes tend not to pop in and out of design – directly).
    If you look at the diagram in Juran’s book you see an existing process with control limits, a shift in the mean and then back into control but with a tighter set of control limits. Although I never noticed it said specifically it was always my interpretation that during that breakthrough process you lean enough about the leverage variable that then you get it on target what you learned about the variables allows you to bring it back to a state of control (perceived control) with less variation.
    It sounds like we are on the same page or at least adjacent pages.
    Regards

    0
    #178992

    Six Sigma Shooter
    Member

    Mike,
    I thought so – once again, we are in “violent” agreement!  Wishing you and yours a very Merry Christmas.
    Semper Fi!
    Shooter

    0
    #179007

    Mike Carnell
    Participant

    Shooter,
    I figured we were just going different directions around the same barn.
    Thanks. I wish you and the family a safe and happy holidays.
    Regards

    0
    #185006

    MRI
    Participant

    Then who can tell me the difference process time VS Cycle time VS throughput time. I am confused sometimes

    0
    #185007

    DLW
    Participant

    This 1-page explanation may help at least in part:
    http://www.bpex.biz/Lean_Six_Sigma/CycleTime_vs_LeadTime.pdf

    0
Viewing 24 posts - 1 through 24 (of 24 total)

The forum ‘General’ is closed to new topics and replies.