Understanding the OEE Calculation

Overview | What is TPM? | The Six Big Losses | Definition OEE | OEE in Relation to TPM | The OEE Formula | Outline of the OEE Calculation | Advantages of the OEE Calculation | Exercise OEE Calculation | Advantages of OEE Software

The OEE Formula
Introduction The Six Big Losses are divided into three categories of machine related losses: the availability, the performance, and the quality. These are also the main elements for determining the OEE.
The formula The product of these three factors equals the OEE value:

OEE = availability rate x performance rate x quality rate (%)

If there are no losses the OEE is 100% (the ideal machine)
Elements of the formula The following table contains definitions of the elements of this formula.
Element Calculation
The availability rate is the time that the machine is actually producing products, compared to the time that it could have been producing products.

Less than 100% availability rate indicates time loss: breakdowns, waiting and line restraints.
Availability rate (%)
=
Running time (actual production time)
Loading time (time scheduled for production)
=
Loading time – (breakdowns + waiting + line restraints)
Loading time
The performance rate is the actual output compared to the theoretical output (expected output given the theoretical maximum speed of the machine and the actual production time.)

Less than 100% performance rate indicates speed loss: minor stoppages and reduced speed.
Performance rate (%)
=
Actual output
Theoretical output
The quality rate is the good output (amount of good products) compared to the actual output.

Less than 100% quality rate indicates quality loss: scrap and rework, and start-up losses.
Quality rate (%)
=
Good output
Actual output
=
Actual output – (scrap + rework)
Actual output

next >>>