Overall Equipment Effectiveness, otherwise known as OEE short, is a standard used to measure three core areas of your manufacturing process: quality, performance and availability.
A high OEE score means that you’re creating as many quality parts as you can, as quickly as you can, with little to no stop time to speak of. Obviously, nobody gets an OEE score of 100% because none of us are perfect – but it’s still in your best interest to try to get that score as high as you can conceivably get it.
Having said that, customers often have a question of how reworked parts should be included in this calculation. Understanding the situation regarding this is luckily straightforward – it’s just that it requires you to keep a few key things in mind.
The Impact of Part Quality on OEE
One common best practice in OEE has to do with the fact that any parts that need to be reworked should be counted as rejects as they initially go through your manufacturing process.
To that end, quality parts are defined as those that don’t need to go through any reworking at all during this period.
What makes the situation slightly trickier, however, has to do with instances where parts may need to be reworked multiple times in order to achieve that quality threshold. This may happen for a wide range of reasons, but ultimately why it occurred matters less than what you do next.
If you decide to treat your reworked parts as essentially “new” meaning that you’re starting the process from scratch, it will impact your OEE score like any other aspect of your manufacturing process. Doing this is usually preferred in those situations when you’re mixing in reworked parts with those that hit their quality threshold right out of the gate. You’ll need to pay particular attention to make sure that your part counts stay as accurate as possible, however, or you run the risk of skewing your entire OEE score.
If you’re dealing with a situation when rejected parts have been reworked after the initial production was completed, you don’t necessarily have to count this against your OEE score. The thinking here is that the poor-quality parts already caused a hit to your OEE score when they were rejected the first time – you don’t necessarily need to do it again.
But overall, the context surrounding your manufacturing process will likely play a role in determining what, if any, impact these re-worked parts will have. Equally complicating things is the fact that sometimes reworked parts cause your manufacturing processes to run at less than peak speed as they get reworked a second time. Sometimes an issue only affected the packaging of a part and not the part itself – which really shouldn’t impact your OEE score at all.
Still, you need to pay attention to all of this so that you understand what your OEE score is really trying to tell you – and so that you can use it to make the best decisions you can at all times.