OEE Calculators
In the OEE Tools application we can choose a method of calculating OEE for each line. Each OEE calculator describes one type of production processes typically used in manufacturing plants. Default one is the OEE Tools calculator, but it can be easily changed in production line details.
Individual station calculations
For calculating single station indicators following formulas are used:
Availability = Station production time / Station available time
Production time is time that machine has been producing good parts.
Available time is the time sum of production time and non planned downtimes.
Performance = (Good parts + Bad Parts) * product standard time / Station production time
Product standard time is the time that it should take to produce one good part.
Quality = Good parts / (Good parts + Bad Parts)
OEE = availability * performance * quality
Batch process calculator
Batch process is a sequence of steps following predefined order. A batch of products is produced at the end of each sequence, and then these products are moved onto the next step.
That's why all stations on this calculation are treated as independent.
OEE indicators for this calculator use following equations:
Availability = Sum of production time of all stations / sum of all stations available time
Since usually there is buffering in batch processes, availability is calculated directly from the sum of production and availability times as stations are independent of each.
Performance = Sum of all stations good and bad parts * product standard time / Sum stations production time
We know that producing one part should take time defined as product standard time. Then to calculate performance we can calculate this time for all produced parts and compare it against time that machine has been working.
Quality = sum of all stations good parts / sum of all stations good and bad parts
This is a simple calculation of what percentage of good parts were in the total production.
OEE Tools calculator
This calculation is similar to the batch process, but here we take that the indication of performance for the whole line is the performance of the last station (representative). We can think of it as the number for final products is dependent on the performance of the representative station and so is performance of the whole line. Additionally here for performance we are using only good parts multiplied by standard time.
For single station:
Performance = Good parts * product standard time / Station production time
For whole line:
Performance = Representative station performance
This is the default calcualtor used on every new production line
Continuous process calculator
In a continuous process material is moved from start to finish in one flow until a final product. This means that there are no breaks or buffers between stations and production of one station is dependent on output of the previous station.
That’s why even a small drop of any indicator will cause significant change of line OEE.
OEE indicators for this calculator use following equations:
Availability = Multiplication of all stations availability = Availability of Station 1 * Availability of Station 2 * Availability of Station 3 …
Availability of a single station is calculated in standard way, for the whole line it’s multiplication of availability indicator for all stations. When two stations have availability 80%, line availability will be 0.8 * 0.8 = 0.64 = 64%.
Performance = Multiplication of all stations performance
Performance of a single station is calculated in standard way. Multiplication works on the same rules as for availability.
Quality = Multiplication of all stations quality
Quality of a single station is calculated in standard way. Multiplication works on the same rules as for availability.
This process is meant for lines where stations are highly coupled with each other and even a small drop in availability, performance or quality causes a significant reduction of total line OEE.