How to calculate OEE
(Overall Equipment Effectiveness)?

OEE (Overall Equipment Effectiveness) is a Lean Business Metric tool commonly used to measure three critical manufacturing performance components as follows. You multiply the three components. The result will be your OEE score and will be presented as a percentage. See some examples below.

Performance

The speed at which a Work Centre runs as a percentage of its designed speed.

Availability

Asset operating time as a percentage of operating time available. This is often referred to as Uptime.

Quality of Yield

The total Good Units produced as a percentage of the Total Units Started. This is commonly referred to as First Pass Yield or FPY.

How to calculate OEE
(Overall Equipment Effectiveness)?

Performance x Availability x Quality

OEE Calculation 1
Theoretical Production Timer for Actual Good Units Produced

Assume Machine A is a single product machine and is
theoretically capable of producing 1,000 units every hour.

In a 16 hour scheduled production day (e.g. 2 x 8 hour shifts)
Machine A could theoretically produce 16,000 good units.

On say one particular day, if the machine produced
12,000 good units then our OEE would be:

Actual Production Time: 16hrs
Theoretical Production Time for 12,000 good Units is = 12,000/1000 = 12Hrs

Theoretical Production Time for Good Units / Actual Production Time

12Hrs / 16Hrs = 75% OEE

Therefore, there are losses totalling 25% for the day
(equating to 4 production hours lost).

OEE is about looking at the root causes compiling the 25%,
and taking corrective action to reduce the losses and increase the OEE %.

Theoretical Production Time for Good Units / Actual Production Time

OEE Calculation 2
Theoretical Output based on Actual Production Time

Assume Machine A is a single product machine and is
theoretically capable of producing 1,000 units every hour.

In a 16 hour scheduled production day (e.g. 2 x 8 hour shifts)
Machine A could theoretically produce 16,000 good units.

On say one particular day, if the machine produced
12,000 good units then our OEE would be:

Good Units / Theoretical Output (for the scheduled production time)

12,000 / 16,000 = 75% OEE

Therefore, there are losses totalling 25% for the day
(equating to 4 production hours lost).

OEE is about looking at the root causes compiling the 25%,
and taking corrective action to reduce the losses and increase the OEE %.

Good Units / Theoretical Output (for the scheduled production time)

OEE Calculation 3
Availability, Performance and Quality

Assume Machine A is a single product machine and is
theoretically capable of producing 1,000 units every hour.

In a 16 hour scheduled production day (e.g. 2 x 8 hour shifts)
Machine A could theoretically produce 16,000 good units.

On a particular day the equipment/process recorded downtime of 2 hours
(e.g. equipment breakdown, waiting on materials etc..).

Scheduled Production Time = 16 Hrs (2 x 8Hr Shift)
Downtime (planned & unplanned)= 2 Hrs
Available Time (Uptime) = 16 Hrs - 2 Hrs = 14 Hrs
Available Time / Scheduled Time = 14Hrs/16Hrs = 88% Availability

In this example we will record throughput on the equipment/process
as 12,632 units (cycles) for the 14 hrs of Available Time. Also remember
that the machine can produce 1,000 units an hour.

Available Time = 14 Hrs
Total product produced (Throughput) in Available Time = 12,632 units
Theoretical time to produce 12,632 units = 12,632/1,000 = 12.63 Hrs
Theoretical Time / Available Time = 12.63Hrs / 14Hrs = 90% Performance

Out of the 12,632 units (cycles), it was found that only 12,000 of the
units were deemed good units (i.e. shippable units). The other 632 are
accounted as scrapped and/or rework cycles to make shippable.

Performance Time = 12.63 Hrs
Good Units (expressed in time) = 12,000 units / 1,000 per Hour = 12 Hrs
Good Units (expressed in Time) / Performance Time = 12Hrs / 12.63 Hrs = 95% Quality

Availability x Performance x Quality = 88% x 90% x 95% = 75% OEE

Therefore, there are losses totalling 25% for the day
(equating to 4 production hours lost).

OEE is about looking at the root causes compiling the 25%,
and taking corrective action to reduce the losses and increase the OEE %.

Availability x Performance x Quality = 88% x 90% x 95% = 75% OEE

Got a question? Need help?
Contact us to talk to an OEE specialist right now.