How OEE is Calculated?
Shoplogix uses the standard OEE formula for reports. That is:
OEE
= Availability
* Performance
* Quality
where:
Availability
=Uptime [Hours]
/Scheduled Time [Hours]
Performance
=OEE Runtime [Hours]
/Uptime [Hours]
OEE Runtime [Hours]
=Total Production [Parts]
/Machine Rate [Parts Per Hour]
Quality
=OEE Productive [Hours]
/OEE Runtime [Hours]
OEE Productive [Hours]
=Good Production [Parts]
/Machine Rate [Parts Per Hour]
OEE Runtime [Hours]
=Total Production [Parts]
/Machine Rate [Parts Per Hour]
Let’s consider Job-A and Job-B as an example:
Job | Machine Rate* [Parts Per Hour] | Uptime [Hours] | Scheduled Time [Hours] | Total Production [Parts] | Good Production [Parts] |
---|---|---|---|---|---|
Job-A | 100 | 1.00 | 1.00 | 70 | 50 |
Job-B | 1000 | 0.25 | 0.25 | 250 | 250 |
If there is a job, the machine rate is equal to the Job Maximum Run Rate; otherwise, it is equal to the Expected Production Rate.
Let's calculate the OEE of Job-A.
OEE
= Availability
* Performance
* Quality
Availability
=Uptime [Hours]
/Scheduled Time [Hours]
=1 hour
/1 hour
=1.00
Performance
=OEE Runtime [Hours]
/Uptime [Hours]
OEE Runtime [Hours]
=Total Production [Parts]
/Machine Rate [Parts Per Hour]
=70 parts
/100 parts per hour
=0.7 hours
So, Performance
= OEE Runtime [Hours]
/ Uptime [Hours]
= 0.7 hours
/ 1.00 hours
= 0.7
Quality
=OEE Productive [Hours]
/OEE Runtime [Hours]
OEE Productive [Hours]
=Good Production [Parts]
/Machine Rate [Parts Per Hour]
=50 parts
/100 parts per hour
=0.5 hours
OEE Runtime [Hours]
=Total Production [Parts]
/Machine Rate [Parts Per Hour]
=70 parts
/100 parts per hour
=0.7 hours
So, Quality
= OEE Productive [Hours]
/ OEE Runtime [Hours]
= 0.5 hours
/ 0.7 hours
= 0.714
Therefore, OEE
= Availability
* Performance
* Quality
= 1.00
x 0.7
x 0.714
= 0.5
or 50%
Similarly, we can calculate the OEE of Job-B:
OEE
= Availability
* Performance
* Quality
Availability
=1.00
Performance
=1.00
Quality
=1.00
Therefore, OEE
= Availability
* Performance
* Quality
= 1.00
or 100%
However, if you want to calculate the OEE for the entire time both jobs ran, a weighted average based on duration is used for calculating OEE. Essentially, the job with the greatest duration would have more influence on the overall OEE.
That is:
OEE Overall
= (OEE Job-1
* OEE Duration Weight Job-1
) + (OEE Job-2
* OEE Duration Weight Job-2
) + … + (OEE Job-n
x OEE Duration Weight Job-n
)
The OEE Scheduled Duration Weight is calculated as follows:
OEE Duration Weight
= Duration Scheduled Time of Job [Hours]
/ Total Scheduled Time of All Jobs [Hours]
The uptime of Job-A is 1.00 hours.
The uptime of Job-B is 0.25 hours.
The total uptime is the sum of all job uptimes, amounting to 1.25 hours.
So,
OEE Duration Weight Job-A
=1.00 hours
/1.25 hours
=0.8
OEE Duration Weight Job-B
=0.25 hours
/1.25 hours
=0.2
Hence,
OEE Overall
= (OEE Job-A
* OEE Duration Weight Job-1)
+ (OEE Job-B
* OEE Duration Weight Job-B
)OEE Overall
= (0.5
* O.8)
+ (1.00
x 0.2
) = 0.6
Therefore, the OEE Overall
for the entire time of both jobs Job-A and Job-B is 0.6
or 60%
Note that OEE Average
= (OEE Job-A
+ OEE Job-B
) / 2
= 0.75
does not weight based on the job that had the most scheduled time. This is for comparison only, as it is not used in Shoplogix standard reports.