Overall Equipment Effectiveness (OEE) measures the productivity of a machine. OEE takes the performance of a machine and multiplies it with its relative capacity and the quality of its output. The result is a score represented as a percentage for a specific scheduled run.
How to calculate OEE
The formula for calculating the OEE of a machine is simple:
OEE = A x Q x P
OEE = Availability * Quality * Performance
Availability is the measured amount of uptime of a machine during the scheduled manufacturing run.
Availability = Uptime / Scheduled Run Time
Quality is the number of units produced in a scheduled run time that meet the quality control levels and do not possess defects, divided by the total number of units that are produced in that scheduled run time.
Quality = Acceptable Units / Total Units
Performance is measured as a percentage of throughput of the machine, compared to its actual overall capacity.
Performance = Throughput / Ideal cycle time
Different methods of calculating OEE
The definition of OEE above is a widely used industry standard definition. However, OEE can be calculated in different ways, to fit the needs of specific operations in an organization. A common way OEE is changed involves simplifying the variables involved:
Simple OEE = (Ideal Cycle Time x Good Parts) / Planned Production
Utilizing the more traditional OEE formula of OEE = A X Q X P gives more insight than the simple formula, allowing you to better implement changes.
Another way OEE can be changed is by adjusting the way you calculate variables:
For example, if your shop is running a training for an operator, you may not want to calculate it in your overall OEE until the operator is fully trained. So you may calculate:
OEE = ([Uptime / Scheduled Run Time] – Training Time) x Performance x Quality
Changing the basic OEE calculation can add complexity, but may provide insight into specific data that your organization is interested in.
However you chose to calculate your OEE, capturing it with a digital tool that allows configurability is essential to effectively managing OEE.