OEE QUESTION

[AndrewUK]

OEE = Availability x Performance x Quality


This question relates to changeovers/setup of a machine. The machine goes down for a change over/tooling change (40mins), it then starts back-up and runs for 20 mins before reaching good repeatable parts. In this 20 mins of production it is intermittently stop starting (running slow) and actually produces some good parts which count towards shift total.

The question then is how to deal with this 20 mins of setup/running slow and the good parts produced within this 20mins.


Ex. 1
By definition “Setup is the time taken to changeover a machine from last good part to first good repeatable part”. So if we take 60 mins (40+20) as the setup time and place into the availability how do you account for the parts produced within this time, as this could result in over 100% performance.

Ex. 2
Take set-up as 40mins and except that the 20mins goes into speed losses/performance. This would allow any good parts to be accounted for would performance would not exceed 100%. My concern with this is that set-ups now appear to take 40mins looking at the data.

Have you encountered a scenario as above and how did you deal with it? Any ideas or suggestions welcome.

 

[RAH1234]

For whatever reason, there is a lot of variation at startup. Whether variation is seen at startup, randomly throughout the run, or attributed to a specific event it has the same negative effect on overall efficiency. Even though the machine is producing scrap and running at a reduced rate it is using all the resources required for producing acceptable parts.

It sounds as if you have some process control issues that need addressed; if the machine is capable of making some good parts during the first 20 minutes, it ought to be capable of doing it repeatedly.

 

[AndrewUK]

I agre, some of the fixes are quick but some will take time. Moving forward though how do recored withregards to OEE?

 

[tripleZ]

We have similar issues in house. To measure our pressing OEE, we record the count # when setup releases the press to production and the count # when production is ceased. Times of course are measured at each stage. This will give you your production OEE. Setup parts, good or bad, are made during the verification of a production run.

Setup parts are added into the lot, and the Traveler/work ticket reflets this. However it's the monitoring of the press counter (not the final tally on the traveler) that enables us to monitor our OEE. Technically, it's an added step. But it's not time consuming, so we accept it as is.