What is OEE
Overall Equipment Effectiveness (OEE) is the gold standard for measuring the performance and production efficiency of manufacturing equipment. It provides profound insights into the performance and potential of the equipment by assessing its effective utilization in actual production. The OEE score reflects the proportion of efficient time in the manufacturing process, with a higher score indicating a higher utilization rate of the equipment’s production time.
OEE is one of the most valuable key performance indicators in factory workshops. By using OEE, manufacturers can monitor equipment functionality and efficiency, reduce waste, strengthen quality control processes, identify inefficient stages in production, and measure improvement progress. It combines equipment performance, operating time, and production quality, providing a comprehensive efficiency measurement method. As an important tool for continuous improvement, OEE not only helps manufacturing enterprises evaluate current equipment performance but also provides a clear direction for optimizing processes and improving overall productivity.
Three Basic Formulas for Factory OEE Calculation
OEE is calculated based on three main factors: availability, performance, and quality. These components help manufacturers identify losses and optimize production processes.
Availability: It measures the time the device is running compared to the scheduled production time, including planned and unplanned downtime.
Performance: View the comparison of the device’s operating speed with the ideal speed.
Quality: The ratio of the number of qualified parts produced to the total number of parts produced.（11BGN）
1. Availability: Measure of uptime
Formula: Availability = (Actual operating time / Scheduled production time) × 100%
Availability: It covers downtime during production, whether planned (e.g., maintenance) or unplanned (e.g., equipment failure). It represents the percentage of time the equipment is available for operation compared to scheduled time. A high availability score indicates minimal interruptions during operations.
Example:
For an 8-hour shift (480 minutes), minus the 60-minute scheduled break time and 47 minutes of equipment downtime, the actual running time is 373 minutes.
Availability = (373/420) × 100% = 88.81%.
2. Performance: Evaluate operational efficiency
Formula: Performance = [(Ideal Cycle Time × Total) / Run Time] × 100%
Performance = (Actual Output / Theoretical Output) × 100%
Meaning: Efficiency measurement of the equipment in operation relative to its maximum capacity, taking into account factors such as slow cycles or brief pauses. Ideal cycle time refers to the shortest time to produce a unit under optimal conditions. Lower performance often indicates inefficiency issues, such as process bottlenecks or operator errors.
Example:
If the ideal cycle time is 1 second per unit, and the device produced 19,271 units during a runtime of 373 minutes (22,380 seconds):
Performance = [(1×19,271)/22,380]×100%≈86.11%
3. Quality: Ensure the output meets the standard
Formula: Quality = (Qualified Units / Total Production Units) × 100%
Explanation: Quality refers to the percentage of defect-free products in the total production volume. It takes into account defects and rework, reflecting the production line’s ability to meet specification requirements and reduce waste.
Example:
If 19,271 units were produced, 423 of them were defective:
Quality = [(19271 – 423) / 19271] × 100% ≈ 97.81%
4. Overall OEE Calculation
Formula: OEE = Availability × Efficiency × Quality
Meaning: The OEE score combines these three factors, providing a single indicator to measure the overall effectiveness of production equipment. A perfect OEE score (100%) means that the equipment has no downtime, operates at maximum speed, and does not produce any defective products.
Example:
Using the aforementioned data:
Availability = 88.81%
Performance = 86.11%
Quality = 97.81%
OEE = 88.81% × 86.11% × 97.81% ≈ 74.44%
Why Overall Equipment Effectiveness (OEE) is important
Identifying Loss: OEE helps to identify inefficiencies in Availability (可用性), Performance (性能), and Quality (质量).
Increase production efficiency: By addressing each component, manufacturers can simplify operations, reduce costs, and improve overall output.
Benchmark setting: World-class equipment overall efficiency (OEE) scores are typically 85% or above, setting a target for operational excellence.
Conclusion
Overall Equipment Effectiveness (OEE) is an important tool for optimizing factory operations, providing clear insights into equipment performance to help manufacturers enhance efficiency and competitiveness in a rapidly changing industrial environment. By regularly monitoring and improving the three core components of OEE—availability, performance, and quality—manufacturers can identify inefficient processes, reduce downtime, improve product quality, and increase overall productivity. Mastering the calculation method of OEE is crucial for achieving this goal, and in-depth analysis of the production process can drive the company to achieve better business results.（MES）
