# Calculating Overall Equipment Effectiveness (OEE)

A score of 100% is perfect production, a score of 85% is world class for manufacturers, a score of 60% is fairly typical, and a score of 40% is not uncommon for manufacturers that don’t practice lean techniques (TPM – Total Productive Maintenance).

Calculating OEE will help your company identify where to improve quality, where to maximize your existing resources and reduce waste—saving you money in the long run.

Availability considers Down Time Loss.
A= Operating Time / Planned Production Time

Example: A conveyor system is scheduled to run for two 8-hour (960 minute) shifts, with a 30-minute break per 8 hours.
Operating time = 900 min scheduled – 90 min unscheduled downtime = 810 minutes

Availability = Operating time / Planned Production Time
Availability 810 minutes / 900 = 90%

Performance considers Speed Loss
P = Ideal Cycle Time / (Operating Time/Total Pieces)
Ideal Cycle Time is the minimum cycle time that your process can be expected to achieve in optimal circumstances. It is sometimes called Design Cycle Time, Theoretical Cycle Time or Nameplate Capacity.

Example: A conveyor system is scheduled to run for two 8-hour (960 minute) shifts, with a 30-minute break per 8 hours.
Operating time = 900 min scheduled – 90 min unscheduled downtime = 810 minutes
Parts are produced at the Standard Rate of 40 units/hour or 1.5 minutes per unit
The conveyor system produces 525 units during the total day. This is Total Units, not Good Units. Quality is not measured at this point.

Performance = Ideal Cycle Time / (Operating Time of Total Pieces)
Time to produce parts = 525 * 1.5 minutes/unit = 787 minutes (Ideal Cycle Time)
Performance (Productivity) = 787 / 810 = 97%

Quality considers Quality Loss, and is calculated as:
Q =Good Pieces/ Total Pieces

Example: 525 units are produced. 56 are defective.
(525 units produced – 39 defective units) = 469 units
469 good units / 525 total units produced = 89%

OEE considers all three OEE Factors, and is calculated as:
OEE =Availability x Performance x Quality = 0.9 x 0.97 x 0.89 = 0.777 = 77.7%

*Calculation formula taken from www.oee.com. Examples are hypothetical.