My OEE goes over 100%. What’s wrong?

Q: My OEE goes over 100%. What did I do wrong?

Our hypotheses…

We came up with the following reasons why this could happen

  1. Our time normes are not ok and our people can reach very quickly speeds over 100%
  2. We have 0 ppm and 0 bad parts, but I don’t think this is true; I even believe this cannot be reached even in a fully automated process.
  3. We didn’t stop for maintenance of the machine – but on the long term I don’t think that this is sustainable.

Are we correct?

Arno Koch •  Indeed, several possibilities can lead to an OEE going over 100%. if OEE goes over 100% the definitions should be carefully checked since with correct definitions (and without seriously re-engineered machine or product) this is not possible.

What if we don’t stop for maintenance?

Not stopping for maintenance can not be the cause for this phenomenon since in that case availability would go up, maybe even until 100%, but it never can go over 100% since you can not put more time in a shift than 100%.

Not reporting defects?

Not reporting defects does not influence the performance rate since this -by definition- contains good and rejected product. It would raise the quality rate, but you can not make more than 100% quality.

Keep running during breaks?

Cheating on run time (you say you where running during the break but didn’t) does raise availability but equally decreases performance.

“hiding time”?

“Hiding” time (you where running but did not report it) could bring up the phenomenon, but why would anyone do this regularly?

How can OEE go over 100%?

The way to achieve this phenomenon is to produce more output than possible according to the definition; so in cases where the defined maximum speed is lower than the real maximum speed.

This is the reason why the THEORETICAL maximum speed should be defined as the 100% value of performance. Do not use some ‘practical or actual maximum’ that is just practical for the moment but can be improved in time. If the machine CAN go faster it WILL go faster one moment or the other.

The golden rule for Maximum Speed in OEE:

The real maximum speed can only be improved by re-engineering the machine or product.

 Also see: “Can performance go over 100%?”

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