## Quality Rate can not be determined immediately

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 OEE for the day is no longer possible in this way. What number should I now use?

## Measuring batches that run beyond the shift-limit

Q: When a batch is running at the moment when a new shift-crew comes in, we do not know how much volume was produced yet in that batch. How do we determine an accurate OEE now?

# Continue reading →

## OEE – OOE – TEEP explained

Q: What is the difference between the OEE, OOE and TEEP measurements?

## Machines are not always planned to run

Q: We run a 3 shift operation of 120 hrs a week.
Some of our machines are not 100% loaded due to the product mix we have.

How should we calculate the OEE?

## Calculate a monthly OEE

Q: My boss wants me to calculate and present a graphical OEE representation on a monthly basis. I present this as I do with the daily data. I calculate the monthly OEE  by taking the average of the daily OEE’s.

Is it alright to present a monthly OEE of the machines by calculating the average of the daily OEE’s in a month?

## My OEE goes over 100%. What’s wrong?

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

## How to calculate OEE with mixed output?

Q: Our machine can run mixed output, so several different products, each shift. Till now we just recorded the time the machine was running and the output we had. Our software now requires that we register activities and quantities to account for every minute in a shift. But we are not tracking the number of minutes it ran each product.

## Measure OEE for Batches

Q: Is it possible to use OEE in an intermitting production, when producing batches?

Arno Koch •     There are two problems in this question;

1. How do I measure an accurate OEE when running batches
2. Can I measure an OEE for each batch

I will answer the second question here;

The major goal of OEE is to identify whenever the machine is not running smoothly causing losses. In the situation, when a machine has to be stopped regularly (even when there seem to be ‘plausible reasons’), it makes sense to identify and quantify such reasons. This might reveal a new perspective to the ‘accepted’ equipment losses.

Losses do not only occur while running batches. A major part of the losses might occur between the batches. So we want to see those losses.

• If you do not run between batches (ie because the line is not balanced) register “waiting for process X”.
• If buffers are full register “No output due to buffer full” etc.
• If demand is irregular register “waiting for production order”.

This will indicate where to focus your improvement efforts, being the main goal of OEE.

The problem would be: Are you going to assign such losses to a/the batch? Probably not since there is no correlation to that batch. So you would miss this loss…

So measuring OEE of batches only, could make you blind for a substantial part of the losses on the equipment. I would rather widen your timeframe where you measure OEE (in cases of long batch time). Instead of OEE per shift, consider an OEE per 24 Hr or per week. In this case you will keep all losses in the picture.

The question you should consider is this: If you measure OEE only during batch-time, what are you NOT measuring?
If the process is intermittent, I would like to know this! How often is it interrupted? How long? How much variance in the intervals? Here are many indicators; something strange is going on in the value stream.
Many batch processes run on capital equipment. Why is it not ‘batching’ all the time? Blinding out setups, preparation time, loading and unloading etc. etc. might bring you to wrong conclusions about what to improve in the equipment, the line or the value stream.

The point is: Beware of sub-optimization. While analyzing many hundreds pieces of equipment, I found out: Losses can be in complete other areas as usually searched for, or where you might expect them. The only way to find them is not to blind out any shelter where a loss might hide.