Focusing on Quality in OEE
Key takeaways:
- Quality measures how many units meet standards.
- Quality rate is calculated as Good Units / Total Units.
- Quality losses include defects and rework.
- Aim for more "Right First Time" production to improve OEE.
Understanding quality in manufacturing
The final component of the OEE calculation is Quality, which measures the amount of production throughput that meets the required specifications compared to the total amount of production throughput.
In other words, the Quality component of OEE measures the effectiveness of a manufacturing process in producing good-quality products.
Quality is crucial in manufacturing because it directly affects customer satisfaction.
Poor quality also leads to rework or scrap during the production process, which wastes materials and time, negatively impacting the bottom line.
How to calculate quality
Quality is calculated as the ratio of Good Units to the Total Units Produced.
Good Units are those that meet quality standards without needing rework and are also known as Right First Time Units.
Here's how to calculate the Quality rate in OEE:
Quality rate =
((Processed amount – Defect amount) / Processed amount) x 100
You'll also see this expressed as:
Quality rate =
(Right First Time / Total Production) x 100
Here's the Quality calculation as an image:
Factors affecting quality
For quality losses, we have two categories; defects in process and reduced yield.
Defects in process occur when equipment or processes cause issues with units produced. For example, equipment that requires warm-up time causing defects until it reaches a steady state.
Reduced yield comes from scrap or rework counts. Rework is included as lean manufacturers aim for “Right First Time” production.
And that's it for our formal introduction on how to calculate Availability, Performance, and Quality according to Nakajima. Stay tuned for our next lessons where we put some actual numbers on these concepts and look at Factbird's waterfall approach to OEE calculation.