## Practical example of OEE Calculation

The application of the OEE calculation can be a bit confusing. In order to facilitate greater understanding, a practical example of the OEE Calculation will be discussed.

Please be advised that this is simple example of how the OEE calculation works, and, as such, does not contain vast amounts of data that would also be factored into the calculation in a real-life situation in a factory. For practical purposes, this example has been kept as simple as possible. There are many other downtime losses that would be used in the calculation in reality.

The table below contains hypothetical shift data which will be used to complete the OEE calculation.

Take note that the same units of measurement (in this case, minutes and parts) are consistently used throughout the calculations. Knowing that the OEE Calculation is based on a combination of the availability rate, performance rate and quality rate, each of these components need to be calculated before the final OEE percentage can be deduced.

# Availability Rate

Now, this shift’s data needs to be used for the Availability rate calculation. The information specific to this calculation is as follows: From the above tabel, it is clear that:

• The Potential Production Time. which refers to the total operating time that the shift was scheduled to run, is an 8 hour shift of 480 minutes.
• Production time was lost due to two instances of tea breaks (30 minutes in total), one break time (30 minutes) and quality stops (to the total of 47 minutes). This means that the total time lost is 107 minutes (= 30 + 30 + 47).
• Therefore, the actual time that the machine was in production and producing parts is 373 minutes (= 480 - 107). The calculation of the availability rate is:

Availability       = B / A x 100

= 373 / 480 x 100

= 77.7%

# Performance Rate

Now, this shift's data needs to be used for the Performance rate calculation. The information specific to this calculation is as follows: From the above table, it is clear that:

• The Hourly Standard, which refers to the number of parts that should be produced per minute, or in other words, the theoretical output, is 60 parts per minute. Theoretically, the totla number of parts that should be produced during the 373 minutes of production that took place during this shift, is 22 380 parts (= 373 x 60).
• The amount of parts lost due to speed would be calculated by subtracting the actual amount of parts produced in total (both good and bad parts) from the number of parts that should theoretically be produced during this shift. This means that the amount of parts lost because of reduced speed (or poor performance) is 2 659 parts (= 22 380 - 19 271). The calculation of the performance rate is:

Performance     = D / C x 100

= 19 271 / 22 380 x 100

= 86.1%

# Quality Rate

Then, this shift's data needs to be used for the Quality rate calculation. The information specific to this calculation is as follows: From the above table, it is clear that:

• The total number of parts actually produced during this shift (good and bad parts) is only 19 271. This is the actual output for this shift. The number of those parts that were declared as scrapped parts is 423. This means that the actual number of good parts produced is 18 848 (= 19 271 - 423). The calculation of the Quality rate is:

Quality              = F / E x 100

= 18 848 / 19 271 x 100

= 97.8%

# Overall Equipment Effectiveness Calculation:

An OEE calculation can be performed, using the amounts calculated for availability, performance and quality: Since percentages cannot be multiplied, it is important to first convert each percentage to a decimal figure. This means that:

OEE  =  0.777 x 0.861 x 0.978

OEE  =  0.654

Therefore,

OEE  =  65.4%

HaldanMES displays this OEE information: HaldanMES provides insights into the losses that were incurred during this shift: HaldanMES also indicates performance information for this shift, including minor stops and actual yield: 