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OEE calculation for machine idle time

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  • #40138

    Robin
    Member

    In the system that I have the machine has to be turned off when the turntable gets filled-up. This happens because the packers at the end of the  line are a lot slower than the speed at which the machine operates. Would this be considered like any other unscheduled stop in the OEE calculations?
     
    Robin

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    #123652

    “Ken”
    Participant

    Robin,
    I’m not certain idle time due to a system constraint should be considered in the OEE calculation.  But, I wonder what would happen if you focused on removing the bottleneck at the end of the line.
    Ken

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    #123654

    Andejrad Ich
    Participant

    “Overall Equipment Effectiveness” — anything that causes the equipment to stop should be recorded, including a constraint caused by a manual operation downstream.  That collected data will demonstrate the impact/severity of the constraint and likely provide justification to improve it.  Don’t generate OEE’s that pretend the machine is running when in fact it is not. 

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    #124233

    Subikash Roy
    Member

    May be you can slow down the machine to stop interruption because packers are slow. Once the packers pick up the speed you can increase the speed of the machine. Otherwise it becomes part of the OEE calculations. This is my logical analysis.

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    #124238

    Paul Gibbons
    Participant

    Hi Robin,
    Are you measuring the OEE of the overall system or of the individual machines?
    My suggestion to you would be:
    First of all measure the OEE of the overall system with the cycle time time being the total throughput time of one product through the process. Have a top level downtime indicator for each machine in the availability part of the calculation.
    By doing this you will be able to identify (using Pareto) which piece of equipment is responsible for the most downtime. You can then focus on recording the individual faults on that particular machine as part of the overall system OEE. For example:
    Availability Losses
    1, Lathe
     1.1 spindle failed to start
     1.2 chuck failed to close
     1.3 loading error
     1.4 etc etc
    2, Hob
    3, Drill
    4, etc
    By doing this you will understand that the idle time of the machine that gets turned off is not relevant to the OEE equation.
    If this is not clear please let me know what I need to explain further.
    Thanks
    Paul

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    #124241

    Peppe
    Participant

    Robin,
    I don’t know why your industrial engs set up a unbalanced line with so evident bottleneck, but I think you main question is : is your line able to satisfy your demand ? If so, the different speed must be considered ad scheduled stop, many lean org have assets oversized that work under their capacity, to achieve required lead time for on demand organization  and this could be a choice of your ind engs.
    If not, it is a different story, capability story, to be solved with ind eng.
    Rgs, Peppe
     

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    #124329

    jediblackbelt
    Participant

    How I have always attacked OEE for a cell would be to calculate the uptime based on total machine hours.  So if you have a total of 10 machines and they can all run for 8 hours you have a total of 80 machine hours to work from.  If you have a machine (non-bottleneck) go down for 5 hours you subtract the 5 hours.  If you have your bottleneck go down for 5 hours you lose those hours across every machine so you lose 50 hours of time.  This may or may not be true because of WIP, but of course you should be working on a one-piece flow and regardless time loss on a bottleneck will eventually hit every piece of equipment. 
    The other thing you could look at is rolled throughput yield.
    Just how I have used it in the past.

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    #124606

    [email protected]
    Participant

    Hi,
    If there are downstream blocks to, or upstream blocks behind a specific machine, due this machine have stops for a short moment, this machine is still UP or available and will not lead to a lower OEE.
     
     

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    #124612

    Dog Sxxt
    Participant

    What is the point having a machine with 100% computed OEE, but your actual output is much lesser than desired output due to the constraint at downstream?
    A stoppage is still stoppage and it has to be reported unless you are maintenance people who want to impress the big boss who never come to the shopfloor.

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    #124615

    Dog Sxxt
    Participant

    Machine is UP but non productive..that is a stupid waste of electric bills, capitals, etc.
     I always like my competitors UP their machines for the sake of uptime.

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    #124621

    “Ken”
    Participant

    DS,
    Agree completely!
    Ken

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