How Is Changeover Time Calculated in OEE?

Six Sigma – iSixSigma Forums General Forums Tools & Templates How Is Changeover Time Calculated in OEE?

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    My company just started using OEE and needless to say it is a learning curve for us. We have always calculated OA, which is somewhat similar to OEE. We have a consultant helping us to transition from OA to OEE.
    I have two questions that I need help with.
    #1. Can someone calculate this question and write it out for all to see…
    Example: Operating Time is 480 Minutes, (2) breaks at 10 minutes each, Lunch break at 20 minutes, (1) changeover at 30 minutes, Total Produced 600 parts, Zero Scrap, Cycle Time is 30 Seconds per part. Can someone calculate what the OEE percentage would be and show your work?

    Question #2:
    The consultant we have told us today to subtract changeover time (30 minutes) from available operation time (480 Minutes). He stated that changeovers are scheduled, thus should be counted as Scheduled Downtime. ( 480 – 30 = 450 Minutes of Available Operating time) This is something new to us, as our company has never counted changeover time as scheduled downtime and subtracted it from operation time. Is this the correct way to calculate OEE?


    Chris Seider

    Question #1…yes you can. Total GOOD parts produced divided by (total operating time including losses X theoretical parts/time unit) is your OEE.

    Question #2…changeover time is a loss in ANY well run Lean/TPM/Six Sigma program. My two cents or maybe two dollars in this manner. Would the company be hit if changeovers took an hour instead of 2? Unless you tell me the changeover is ALWAYS during unmanned shifts–then you could argue it’s not included unless it ran over into the manned shifts to produce the product/service.


    Justin M

    OEE is a calculated by first getting max number of parts. Since 480 is an eight hour shift I’m going to assume the breaks are paid and within the eight hours…meaning you have 440 minutes of production availability. Changeovers are not an excludable downtime unless as Chris mentioned they occur outside production time and are completed by indirect labor (yourself for instance) 440 minutes @ 1/2 minute cycle time yeilds maximum theoretical parts produced of 880. 600/880=68% your OEE calc may only include total number of good parts. You could also back calculate to find how much DT or speed loss you had. @~70% you had almost 2 hours of DT or speed loss that shift. 1/4 was your changeover. I’d be looking elsewhere to find the rest.

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