Introduction to OEE

OEE (Overall Equipment Effectiveness) can help you determine the percentage of time that your production equipment is being fully utilized.

What OEE can do for you

OEE can help you:

• Learn if you are getting the most efficiency from your assets.

• Pinpoint times and shifts when production tends to flourish or falter.

• Increase equipment reliability and reduce downtime through planned maintenance rather than reactive repair of equipment when it breaks down.

• Determine actual equipment or process performance relative to equipment or process capability.

• Identify missed opportunities when more first-pass yield could have been produced.

• Increase awareness about first-pass yield among workers who have received training on its merits.

OEE Limitations

• The basic OEE calculation—OEE= Availability * Performance * Quality—gives equal weight to the importance of each of these metrics. Your organization's goals should be considered when you place more emphasis on one of these metrics over another. For example, increasing your cycle time could raise your Performance percentage, but hamper your first-pass yield (Quality) percentage.

• Increasing the rate of production alone can result in overproduction: overstock, overfill, or too much WIP. Plus, it can lead to lower quality, which defeats the point of OEE: getting the most from your scheduled production time using the assets you have.

• OEE can help you identify areas of constraint, but it does not tell you causes for constraints.

• The focus of OEE should be on preventative maintenance through scheduled downtime instead of increasing the speed at which equipment is repaired.

• OEE is only one indicator of productivity. Using OEE along with DMS and SPC data can help you identify processes that are lagging and help you determine root causes.

What are good OEE numbers?

It can be misleading to compare OEE numbers between manufacturers, or from plant to plant within the same company because no two plants, products, equipment, or human assets are identical. A good use for OEE numbers then is to establish baseline percentages for your organization and work to improve them—without comprising first-pass yield.

Following are OEE percentages that are typically considered to be good.

Availability      90%

Performance   95%

Quality            99.9% (may be low for some Six Sigma initiatives)

Overall OEE     85%+ for World Class Manufacturing (60% is average).

How to collect OEE data

• See Requirements for collecting OEE data

How OEE is calculated

• See OEE Calculations

OEE Chart types

• See OEE Chart types