“Overall Equipment Effectiveness”, known in the jargon as “OEE”, is a composite metric which quantifies how far a factory is from its optimal performance – the performance level for which it was designed to.

OEE is an aggregation of three separate factors:

1. Availability - Represents the percentage of the scheduled time that the operation has to operate.

Formula:

Availability = Uptime / Available Time

Example:

Uptime = 450min Available Time - 60min Non-Scheduled Downtime = 390min

Availability = 390min / 450min = 86.6%

2. Productivity - The speed at which each work center works as a percentage of the optimal productivity for which it is designed to.

Formula:

Productivity = Estimated Time / Time Spent

where Estimated Time = Quantity Produced * Operation Cycle Time / Operation Quantity Ratio

Example:

Operation Cycle Time = 1H15m

Operation Quantity Ratio = 5

Quantity Produced = 10

Time Spent = 2H44m

Productivity = (10 * 1H15 / 5) / 2H44 = (10* 75 / 5) / 164 = 91.5%

3. Quality - The good units produced as a percentage of all the units produced.

Formula:

Quality = Units OK Produced / (Units OK Produced + Units NOK Produced)

Example:

Units OK Produced = 221

Units NOK Produced = 21

Quality = 221/(221+21) = 91.3%

OEE calculation:

In these examples:

OEE = Availability * Productivity * Quality = 86.6% * 91.5% * 91.3% = 72.3%

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