# Calculating Hourly OEE

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• #53799

Ionescu
Participant

OEE HOURLY CALCULATION
As we all know OEE is a multiplication of Availability, Performance and Quality.
There is some debate here on what formula it should be used to calculate OEE every hour. We are a one piece flow environment having the automotive industry as a customer.
Here are some of the formulas that our corporate office came up with:

OPTION 1:
The OEE by hour calculation should be:
The total number of good parts produced for that hour/the goal
of parts for that hour.
The goal is calculated using the available time we are running
during the hour/the Takt time.

OPTION 2:
The hourly OEE calc is:
Total assemblies produced – Rejects /Standard machine capability
for one hour

Also during a visit at the plant near our corporate office I saw OEE majority over 100% and I was very surprised knowing that 85% is considered “World Class”

Thank you very much.

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#191473

Euston
Participant

Personally, I’ve never seen OEE calculated using Takt time. The idea is to capture your equipment throughput based on its capability, not to quantify your productivity with respect to demand.

That said, your Option 2 is closer to the correct calculation.

Just be sure you are measuring it at the constraint in your workflow.

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#191475

Putnam
Participant

I could see using Takt time to get a variation of OEE, but you’d then have to consider being too far above or below 100% as a quality issue.

Maybe use (actual rate – absolute value of (actual rate – Takt Time))/Takt Time?

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#191476

Ionescu
Participant

Thank you very much for your answers. I thought the same way that using Takt time is not a good approach. On the other hand on option 2 when I asked how to calculate the “Standard Machine Capability” I was told that I should be using the “Standard Work Combination Sheet” and take the total time from there which doesn’t make sense to me. Am I wrong?
So at your facilities how you calculate OEE live?

Thank you very much for your help.

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#191481

Euston
Participant

We use an online database and software package to calculate OEE. It is ‘semi-live’, meaning it can be as current as we want, but is dependent on someone entering data in the software. Typically, we are doing this at end of shift. If we wanted to do this live, we could, but it’s not as critical to our operation, so we don’t.

Our calculation is based on the OEM rated speed of our main asset on our lines. (Good Units produced/ Theoretical Units Produced [OEM Speed (units/hr)* Machine Operation Time (hr)]

Machine Operation Time is defined, generally, as the time the asset is ‘on’ and available to run. In that case, it includes unplanned downtime, but excludes things such as cleaning time or PM work.

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#191519

MBBinWI
Participant

While hourly OEE (or OEE by the minute, or even second, or better yet instantaneous) is an interesting concept, OEE really is only meaningful over a time period where all planned and unplanned events are accounted for. If I have a 100% OEE for 50% of the available operating hours, and zero OEE for the other 50%, I have 50% overall. I should not reward (or rejoice) during the 100% periods, nor punish (or lament) during the zero % periods. There are reasons for each, and that is the critical learning. Uncover it. OEE is not the objective, just a means for looking at some aspects of the journey.

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