We are computing OEE taking all machines that we have inhouse together. Setting time, breakdown hrs., etc are taken for all machines together and a single OEE is computed. Is this right? or should we compute for only the contsraint machine.

I would be looking at each machine. You may have a process where you have recognized a 'constraint' machine and bought a second one or something like that. I don't know how you could do a single OEE without having data on each machine/operation/etc.

You could measure this in 2 ways. First, calculate OEE for individual machines. Then use these figures to calculate plant efficiency. This would highlight individual machine concerns. You could have a plant efficiency at 75% but this would not show that 2 machines could be running at different levels of efficiency. So in effect one machine could be carrying the other. I guess its all down to the amount of time and effort you can put into it each week/month and what data is available.

I have attached an example of the difference in machine efficiency and plant efficiency for you to review.

If you are using OEE to establish throughput, you are making it more difficult to identify bottle necks by lumping all equipment together.

What I have found to be very beneficial in the past has been to do a Value Stream Map before applying the OEE calculations. It identifies restraints and then you can put actual numbers on how the restraints are detrimental to the process.

Thanks everyone for the response.

Randy,
What does value stream map mean? Kindly explain.

For some reason there was no reply-
Try the folowing threads

Have any of you heard of a Value Stream Mapping (http://elsmar.com/Forums/showthread.php?t=10018)

VSM (Value Stream Mapping) - Use constraints or leave 'wide open'? (http://elsmar.com/Forums/showthread.php?t=11968)

Howard - Thanks for noticing and helping out!

Also see: OEE - Overall Equipment Effectiveness - Initials and Definition (http://elsmar.com/Forums/showthread.php?t=13138)

Here's another worksheet. Just enter the data in the yellow fields.

Wayne

Hi, is there any link explaining the theoretical correlations between availability, performance, quality - so when I improve e.g. availability, which impacts does this have on performance and quality? thanks a lot

Hi, is there any link explaining the theoretical correlations between availability, performance, quality - so when I improve e.g. availability, which impacts does this have on performance and quality? thanks a lot

That isn't the point ot OEE, to determine some correlation. The purpose of OEE is to:

1) Be used as a baseline for tracking progress
2) Identify the biggest area of opportunity

Just take it for what it is, as it isn't meant to be an exercise in stastical analysis.

Wayne