Measuring OEE on a continuous flow line
November 13, 2008 by david.evanson
Something that’s often missed ouf from the standard OEE definition results in one of the questions that frequently comes up when we’re talking to new sites about OEE measurement: “Which machine do I measure my OEE from?”.
Firstly, let’s explore the real value of knowing your OEE: A lot of sites measure what they produce, very few sites know how to use this data to make more. OEE is a great example of this because It’s not how you measure the OEE figure that matters, it’s how you measure your OEE losses that makes the real difference.
The most typical way that most sites measure their output is through cases produced at the end of the line (typically a palletiser). This is by far the most common form of OEE measurement that we come across. Whilst this gives you a good idea of what you’ve made it won’t help you to identify what you’ve lost - which is what OEE is really all about.
The real ‘meat’ of your OEE calculation isn’t the % OEE number - that just tells you what you’ve made, it won’t help you identify what you need to fix/improve to get that number up.
What you really want to be measuring are your losses to OEE:
- 3 Loss: Quality, Performance, Availability
- 6 Loss: Breakdowns, Minor Stops, Speed Loss, Planned Downtime, Quality loss in running, Quality loss on startup.
With this information you have the capability to start CI plans to improve performance. It’s nice to know your OEE….it’s ESSENTIAL to know your losses.
So here’s a question for you to consider: At what point in your manufacturing process is it important to know either the 3 or 6 Losses to OEE?
In my next blog I’m going to explore the “Theory of Constraints” by Goldratt and Cox (see the Amazon link below), and how you need to apply this theory to get an OEE and Loss number that will help you improve.
Here are a couple of web-links that may help you to explore that question:
http://www.amazon.co.uk/Goal-Process-Ongoing-Improvement/dp/0566086654
http://en.wikipedia.org/wiki/The_Goal_(novel)
http://en.wikipedia.org/wiki/Theory_of_Constraints
