Measuring overall equipment effectiveness (OEE) has become the ideal way for determining how much of the manufacturing time is productive. By eliminating downtime, increasing production and improving product quality, measuring OEE has become crucial for companies focusing on lean manufacturing.
But just how exactly do you calculate OEE? There are three main metrics that determine OEE: availability, performance and quality.
This is the amount of time your equipment is running during a scheduled shift, taking into account all planned and unplanned stops during production time. When calculating availability, a score of 100% means production never stops, which is ideal in lean production.
To calculate OEE availability, use the simple equation:
Run Time/Planned Production Time
The amount of stops and idle time your production system has determines your performance score. A score of 100% means that production is always running at max speed. To calculate OEE performance, use the equation:
Actual Production/Ideal Production
While availability and performance measure how fast and how often your manufacturing process is working, quality measures how many usable parts are being produced. It’s ideal to have 100% of parts usable at the end of production.
To determine your quality score, use the equation:
Good Parts/Total Parts
Putting it All Together
Once you have measured availability, performance and quality, calculating your OEE score can be accomplished with the following equation:
Availability x Performance x Quality = OEE
A score of 100% means that all parts of the manufacturing process are running efficiently at all times.
But what if your score is not 100%? What if you discover that your production process is not very efficient at all?
By measuring all parts of the manufacturing process individually, calculating OEE helps you see which areas of the manufacturing process need improvement. If you are producing quality parts, but do so at a slow rate, you know that you need to improve performance. If machines are constantly running, but half your parts are not usable, you know that you need to focus on improving quality.
That is what makes OEE metrics so valuable. In addition to showing how efficient your manufacturing process is, it also shows you which areas can be improved upon.