OEE is a measure of how well a planned production time of an equipment is utilized to produce good products. It can be measured from 0% to 100%.
Its not only the equipment, effectiveness of achieving target number of good products, of all operations, whether it is manual, automatic or semiautomatic can be measured using OEE.
Now we shall discuss all factors which will affect OEE.
OEE Factors
OEE depends on three major factors.
- Availability
- Performance
- Quality
We will be discussing these three factors in the following sections…
How to calculate OEE
We can calculate OEE by two methods. One is very simple and less data is required. The other one requires more data, but for improving OEE we prefer second method since it has more data.
Lets move into detail…
OEE calculation – Method 1
Following formula is used for calculating OEE in this method.
OEE = (Total no of good products produced × cycle time) / Planned production time
But in this method, we did’t get an idea of which three factors of OEE is lagging behind. Only after knowing this information, we can improve those factors.
But for quick calculation we can use this method.
OEE calculation – Method 2
Initially we need to calculate three factors, Availability, Performance and quality.
And finally OEE is calculated by multiplying these three OEE factors.
Lets look in to these factors, in detail…
Availability
Availability factor is the measure of how well a planned production time is used for producing products.
Availability is calculated by the following formula,
Availability = Run time / Planned production time
Run Time is obtained by reducing idle time from Planned production time.
Run Time = Planned production time − Idle time
Idle time is the time for which machine is not running. This can be due to breakdown, material shortage, power failure, change over, etc.
Performance
Performance factor is a measure of how well a machine is able to maintain its cycle time for producing parts.
Performance factor is calculated by following formula,
Performance = (Cycle Time × Total products produced) / Run Time
Cycle time can be calculated by time study.
Quality factor
Quality factor measures how well a machine is able to produce good parts.
Quality factor is calculated by following formula,
Quality factor = No of good products produced / Total no of products produced
OEE calculation
OEE is calculated by multiplying the above three factors
OEE = Availability × Performance × Quality
If the equations for Availability, Performance, and Quality are substituted in the above and reduced to their simplest terms the result is:
OEE = (No of good products produced × Cycle Time) / Planned Production Time
OEE calculation Example
Now let’s walk through a complete example using the method 2 of OEE calculation. Here is data recorded for the first shift:
| Element | Time |
| Duration of shift | 480 minutes |
| Total break duration | 2 nos 15 minute tea breaks and 30 minute lunch break |
| Downtime | 55 minutes |
| Cycle Time | 40.0 seconds |
| Total no of parts produced | 490 products |
| Total no of parts rejected | 40 products |
Initially we need to calculate the following …
Planned production time
Formula for calculating planned production time is,
Duration of shift − Total break duration
480 minutes − 60 minutes = 420 minutes
Run time
The next step is to calculate the amount of time that production was actually running.
The formula is,
Run Time = Planned production time − Idle time
= 420 minutes − 55 minutes
= 365 minutes
No of good products produced
No of products produced = Total products produced − Total rejected nos
= 490 products − 40 products
= 450 products
Availability
Availability = Run Time / Planned Production Time
= 365 minutes / 420 minutes
= 0.869 (86.90%)
Performance
Performance = (Cycle Time × Total products produced) / Run Time
= (40.0 seconds × 490 ) / (365 × 60 seconds)
= 0.895 (89.5%)
Quality factor
Quality factor = No of good products produced / Total no of products produced
= 450 / 490
= 0.9183 (91.83%)
OEE CALCULATION
Finally, OEE is calculated by multiplying the three OEE factors.
Availability × Performance × Quality
= 0.869 × 0.895 × 0.9183
= 0.7142 (71.42 %)
OEE can also be calculated using a simple method (method 1).
Formula is,
OEE = (Total no of good products produced × cycle time / Planned production time
= (450 products × 40.0 seconds) / (420 minutes × 60 seconds) = 0.7142 (71.42%)
The result is the same in both cases. The OEE for this shift is 71.42%.
Thanks for reading
I am thankful to Mr. Abin Antony for contributing to this article.
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Clearly understood.
Thanks for the good work
It was really helpful. Thank you
Thank you Hilal for the positive feedback