Q:  Sometimes our process is being interrupted; i.e. the oven is stopped at a different moment than planned. At that moment it is not clear whether the product will be OK or not. We will block the product and take samples to determine the quality. This could take a couple of days. Wen everything is OK the product is released, otherwise it is being scrapped. This would have a retrospective effect on the OEE I guess? A correct quality rate -and thus OEE- for the day is no longer possible in this way. What number should I now use?

Arno Koch •  I would approach as follows: The product was not first-time-right. The process is not in control. I would like to see this expressed in the OEE via the quality rate.

I would define two categories of Rejects:

1. Product OK after oven-problem
2. Product rejected after oven problem

Both would decrease the OEE, yet you would still be able to see the correct amounts of good- and rejected products.

See also:

• • First Time Through (FTT) or First Time Right (FTR)
  • How to handle FTT (Quality Rate) when rejects were not being detected?