The Overall Equipment Efficiency is a Lean metric that incorporates process availability, performance and quality in a single metric. We can compare and prioritize processes for improvement based on OEE metrics. It is also recommended to track and prioritize based on the Availability, Performance, and Quality components of the Overall Equipment Efficiency calculation.
Availability: The OEE Availability is calculated as the actual time the process is producing product (or service) divided by the amount of time that is planned for production. The planned time, by definition, excludes all scheduled shutdowns when equipment is not operational, which may include lunches, breaks, plant shutdowns for holidays, etc. The remaining portion of the planned time includes the available time for production, and the down-time. Down time is the loss in production time due to shift changeovers, part changeovers, waiting for material, equipment failures, and so on. It is any measurable time where the process is not available for production, when production had been planned. 100% Availability implies that the process is operational 100% of the time.
Performance: OEE Performance is the efficiency of the process in minimizing its Operating Time. Performance is an OEE metric that is calculated by dividing the ideal process cycle time by the actual cycle time. It accounts for process inefficiencies, such as due to poor quality materials, operator inefficiencies, equipment slowdown, etc. 100% Performance implies the process is running at maximum velocity
Quality: OEE Quality is the percent of total output that meets the requirement without need for any repair or rework. It might otherwise be called the first pass quality. 100% Quality implies the process is producing no errors.
Learn more about the Lean Six Sigma principles and tools for process excellence in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, in his online Lean Six Sigma DMAIC short course ($249), or his online Green Belt certification course ($499).