What is OEE ?
Overall Equipment Effectiveness (OEE) is the key measure used in Total Productive Maintenance. Here we will explore some of the features of OEE.

If you have other queries about TPM which are not addressed here, please contact us directly with your specific questions.

What is OEE ?

OEE is a single measure which shows how much of a product has actually been produced as a percentage of how much could have been produced.

It combines all the standard performance measures - including availability, performance and quality. It should be thought of as the top measure in a cascade of measures.

The OEE Cascade


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What are the 6 big losses ?

The 6 big losses are the 6 main types of loss encountered in a manufacturing operation:

  • Changeover Loss
  • Equipment Failure (stops greater than e.g.. 5 minutes)
  • Start Up Loss
  • Minor Stoppages and Idling Losses (stops less than e.g.. 5 minutes)
  • Speed Loss (slow running)
  • Defects and Rework Loss
They are the fundamental losses which should be measured on the shop floor and can be thought of as the bottom level of a cascade of measures.




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How do we measure OEE ?
OEE is derived by a three step process.
  • Step 1 - Measure the 6 big losses.
  • Step 2 - Calculate the Availability, Performance and Quality Rates
  • Step 3 - Multiply the Availability, Performance and Quality Rates together to give an OEE figure.
These steps are usually performed at the equipment by the operator. The use of a well designed log sheet can assist in this process. If you would like more help or information on measuring OEE or implementing OEE log sheets, please contact us directly with your specific enquiry.


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We already measure these things - why should we bother with OEE ?
Measures are often viewed in isolation. We look at breakdowns, quality losses, speed losses, etc. as individual measures with little or no relation to each other.

We are also aware that many of these measures are the subject of trade offs - for instance, it is a popular belief that if you run equipment more slowly then the number of breakdowns or the amount of quality failures will decrease.

However, if we are looking at the measures independently, it is often difficult to understand the overall effect of changing e.g.. the speed. We may gain more production through better availability and improved quality, but does that increase offset the reduction in output due to the lower speed - and are there other impacts such as an increase in minor stoppages ?

In fact, it should not surprise us that we have difficulty understanding the overall picture because human beings are not particularly good at managing and controlling multiple variables at the same time. OEE helps us by combining these measures so we can view them as a whole. The only decision we have to worry about is whether OEE is increasing (we're producing more for the same amount of production time) or decreasing (we're producing less).

Finally, because OEE is measured and calculated on the shop floor by equipment operators, it encourages greater understanding of performance levels by the people who are actually controlling the process. They can easily see their current performance level, and take steps to improve it in real time.


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How can we monitor and track OEE ?
There are many methods for monitoring and tracking OEE data. Their use is generally determined by the scale of the operation being measured, and the budget available for tracking.

Smaller operations tend to use visual management techniques to display trend data for all of the OEE cascade measures on Activity Boards. This has the advantage of being low-cost and allows easy communication of current trends. Disadvantages can be the amount of time required to update and maintain the trends, and the difficulty of analysing historical data in order to assist Focused Improvement activities.

Large operations usually require an IT solution to allow consistent data capture, desktop reporting and archiving systems. These solutions can be developed internally or, more usually, purchased from external IT suppliers. One such external system is the Treefrog Loss & Waste System.


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