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TAKT TIME Clarification

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  • #49030

    mcintosh
    Participant

    Hi,
    I work as a Black Belt in a services Industry where we setup suppliers in an ERP . We receive these through a workflow which goes through multiple teams . I have a question on the applicability and calculation of TAKT Time for the entire process.
    The End to End process for Supplier setups is made up of 5 (A, B, C, D, E ) sub processes . The number of people in each sub process is different ( 2, 3, 3, 1, 1) . The total available time also varies in all the processes – in hours ( 4, 6, 8, 8, 2 ) .The inventory at each step is ( 10, 12, 5, 5, 10)  if  i now need to find the TAKT time for the entire process what would it be ? Do i find TAKT for evey sub process or for the entire process ? The customer on an average sends 50 requests to be setup.
    Secondly, The observed wait times at each step are – in hours ( 30, 20, 20,10, 10) . How do i account for the inventory pending (Backorders or setups where we are waiting for information ) at each step in the Wait time ? ( We have been internally asked to multiply Inventory * TAKT time + Observed Wait time to get the Correct Wait Time ) is this correct ?
    What happens in cases where you are not able to get the Wait time due to lack of a measurement system etc .. how do we account for this in the Time Ladder
    What is the critical path ?
    Rgds,
    Tom

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    #166873

    SiggySig
    Member

    Takt time = available production time / customer demand.In your case it looks like 50 hours / 50 requests = 1 hour. Based on your wait times it looks like you’re not producing to Takt time.If you don’t have a good wait time measurement due to the process measurement system, I would fix that first.

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    #166885

    GrayR
    Participant

    Takt time is set by demand time by “product type”.  To use the auto manufacturing analogy: if the demand for cars is 24 cars/day, the takt time is 1 hour, and if the demand for trucks is 8 trucks/day, the takt time is 3 hours.  Takt time sets the pace that the operation has to work to meet demand and sets the pace for the ‘Plan’.
    It isn’t clear from your e-mail whether all of the ‘requests’ are the same/similar, so the takt time for each type may differ (e.g., requests Type A may be 24/day = 1 hour takt; and Type B’s may be 8/day or 3 hours takt . . .).
    Ideally, the ‘plan’ time should be related to takt time (if plan time > takt time, then you cannot keep up with customer demand; if planned time takt — the analogy keeps for service processes).  This doesn’t mean that the process has be completed for a specific request within the takt time, its just that requests are completed at the same rate as they come in.  For example, takt time is one hour, so the process has to be capable of completing 24 requests in one day, although each request may take 30 hours to complete.
    Going back to takt as setting part of the ‘Plan’ — this relates to the P-D-C-A (P-D-S-A) cycle for process improvement.  There may be other part to PLAN, including time, such as quality objectives of the process, inventory in the process, etc.
    With lean (actually TPS), using the scientific method (PDCA) for process improvement, when the process is complete (DO-stage), the process result (process time in this case) is compared (CHECK or STUDY) against the plan (takt, if plan time = takt).  If results don’t meet the plan, then process analysis and problem solving takes place to improve the process (ACT).
    In the end, takt time is based on demand — it is similar to takt being voice of the customer based, while it seems that you are trying to characterize the voice of your process.  The ability of the process to meet takt is a measure of capability.

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    #166891

    takttime
    Member

    First determine if your requests are materially different.  If they use different resources and or in significantly different amounts, then you should consider the process to have mutliple product lines and thus, mulitple takt times. 
    A takt time is simply an Available Work Time / Avg Demand ratio for each product category.  It requires nothing else for its calcualtion.  Now operating to takt requires an OEE approach and should be considered depending on your objectives.
    Determine a takt for each product category if more than one exists, calculate the rates of availablity, defectives, and performance.  Then compare the takt to the OEE to identify potential constraints. 
    Cant help you with the Wait Time, but the first step in any assessment is to establish a valid measurement system, as long as the metric itself is deemed critical.
    Good luck.
     

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    #166893

    ngkjrs
    Participant

    at the outset, all these formula will help you have the process working in single-piece flow system. If your manufacturing is of batch process, then you have to re-work your calculations.
    Also do not forget the 50second rule of Takt time. While OEE are to be addressed, you can plan mutiple tasks that would remove the fatigueness in the line.

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    #166900

    mcintosh
    Participant

    Thanks for responding in detailed to the query . Just to clarify some of the things raised in the post.
    1) The teams handle the same “kind” of work. Materially, they are not different . They just need to setup suppliers in different systems ie. one in procurement system (oracle) the other in the accounts payable system (Legacy).
    2) The teams contractually are owned by different Third Party providers ie. they are outsourced to different vendors as a policy decision and have different Service Level Aggrements to complete their tasks.eg) one team contractually has 24 hrs while another team contractually has 48 hours  to complete thier tasks.
    3) Customers are looking at improving their whole process right from the time a requestor submits a request to the time a supplier is setup in the system … and are really not bothered with which team handles the request .. but the biggest problem is to whether i need to use one TAKT for the entire process or should be separate TAKT times for each process step..and if so what is the available time i should take because each step has different available times.
    Thanks.
     

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    #166903

    Ron
    Member

    Takt time is a global number based on product demand and available work time.
    You need to develop a process map to the entire process and calcualte the cycke times for each step in the process. Draw a line on the chart showing the required Takt time and create a bar chart for each step in the process detailing the cycle time to show the relationship between the required Takt time and the actual cycle times . This gives you a roadmap of required improvements.
     

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    #166910

    GrayR
    Participant

    The above posters are correct in that takt time is based on demand as well as the available.  My assumptions were based on a 24 hour available day, but the takt time needs to consider the available hours only.  For example, if there are 24 requests per day, the takt time for a process that is available 24 hours is 1 hour; if the process is available 8 hours (that is, the resource may only work 8 hours/day), then the takt time is 20 minutes.
    If you take the numbers from your first posting, Process B is available for 6 hours (360 minutes), so for 50 requests per day, the takt time for process B is 7.2 minutes.  For process C, the takt time is 9.6 minutes. Etc.  With these takt time, each subprocess can output 50 requests per 24 hour day based on the available time.  If work is batched, then the takt times represent the batch (if three requests are batched in process B, then the total batch takt is 21.6 minutes & and the process still has to meet 1 request/7.2 minutes).  But from a lean approach, work batches create the need for inventory and increase waiting time between process which lengthens the entire cycle time (even though the takt time remains the same).
    Another problem that can occur is that differing takt times (7.2 minutes vs. 9.6 minutes) causes variability in the process and creates the need for inventory in the system.  For example, process D would have a takt of 9.6 minutes, and process E requires a takt of 2.4 minutes. At this disparity, you will need to carry inventory between process D and E so that process E doesn’t run out of work (I think this is what your inventory analysis is showing).  But again, inventory increases the entire cycle time for the set of processes. 
    The process time within each subprocess (A, B,  . . .) does not affect the takt time requirements.  For example, the takt time requirements between process C & D appear to be about the same (equal number of requests and equal number of available hours).  Under steady state conditions (ideally . . .), the rate of output from C (requests/unit time) is sufficient to exactly match the rate of input for D — even though, each request will take twice as long to go through C than D. Again ideally, this would seem to indicate that inventory between the two processes could be reduced which would reduce the overall cycle time for the entire process (by eliminating queue time between processes) — but the processes are not ideal, so you probably need some inventory between operations for buffering variability. 
    From a process improvement standpoint, your resources or available hours have to be allocated (re-allocated) or improved to attain these takt times. Another improvement opportunity is to understand the variability in the processes — reducing variability in the process (e.g., sometimes the output rate for process B is 10 minutes instead of 7.2 minutes) allows you to reduce inventory between subprocesses, which again will reduce the overall cycle time.
    One last suggestion (again, previous posters may have covered this), is to understand the actual rate of output for each operation, which I didn’t pick up from your posting. Based on the inventory, available hours and resources, it appears that process A may be a bottleneck(?)  This also offers some opportunity for understanding and improvement.

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    #166966

    mcintosh
    Participant

    Gray,
    Quick question, so would i need to take a TAKT time for the entire process or break this up into TAKT times for indivual processes . More so because the contractual Service level agreements for each team to turn a request around is different. ie some teams have 24 hrs and others have  48 hrs as mentioned in my previous post.
    Rgds,
    Tom

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    #166969

    Heartland
    Participant

    Tom
    Takt time is a separate animal from turn around.  Think of it like this:
     
    You have to make 24 units (demand) per day.  There are 24 hours available per day. Takt time is 1 hour.  That means your process needs to turn out 1 product every hour to meet demand.  You might have a process that takes 3 days to complete, but still turns out a product every hour.
     
    Regardless of the contractual turn around your Takt time is your Takt time.  An example using 24 parts in 24 hours mentioned above):
     
    Step 1 Mix
    Step 2 Mold
    Step 3 Cure
    Step 4 package
     
    Step 1 takes 8 hours to complete (but you have 8 units all working on 1 part at a time)
    Step 2 takes 1 hour
    Step 3 Takes 1 hour
    Step 4 takes 1 hour
     
    Assuming no delay between steps, no set up, etc it takes 11 hours to produce 1 part, but after the system is primed you turn out 1 part per hour.
     
    The first part you won’t get for 11 (8 Step 1 + 1 Step 2 + 1 Step 3 + 1 Step 4) hours but after that you get 1 per hour.
     
    Determine the Takt time for the product.  If the different vendors supply different “products” then calculate the Takt for each product.  Don’t’ confuse cycle time (velocity, Etc) with Takt time.
     

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