What is OEE? — Overall Equipment Effectiveness Explained
OEE (Overall Equipment Effectiveness) is the most important metric for measuring the productivity of a manufacturing facility or production line. It answers the question: how much of the available production time is actually being used to produce good parts?
The OEE Formula
OEE is made up of three factors:
OEE = Availability × Performance × Quality
An example: a machine runs 90% of planned time (Availability), produces at 95% of its target speed (Performance), and 99% of parts pass inspection (Quality).
OEE = 0.90 × 0.95 × 0.99 = 84.6%
The Three Components in Detail
Availability — the proportion of planned production time during which the equipment is actually running. Losses arise from unplanned stoppages, changeover times, and breakdowns.
Availability = Run Time / Planned Production Time
Performance — the ratio of actual output to the theoretical maximum output. Losses arise from reduced speed, minor stoppages, and idle time.
Performance = (Actual Cycle Time / Ideal Cycle Time) × 100
Quality — the proportion of good parts out of total production, measured on the first pass (First Pass Yield). Losses arise from scrap and rework.
Quality = Good Parts / Total Parts
What Is a Good OEE Score?
Industry benchmarks are generally:
| OEE Score | Assessment |
|---|---|
| < 65% | Needs improvement |
| 65–75% | Average |
| 75–85% | Good |
| > 85% | World Class |
These benchmarks are reference values. Depending on the industry, equipment type, and product mix, meaningful targets may differ. More important than the absolute value is the trend over time.
Why Measure OEE?
OEE makes production losses visible and categorizes them. Without measurement, it is unclear where the greatest levers lie — in Availability, Performance, or Quality. With OEE, improvement measures can be prioritized and their impact demonstrated.
Typical insights from OEE analysis: which failure causes occur most frequently? Which shift or product has the worst OEE? Where are the greatest time losses?
OEE and the Six Big Losses
The OEE concept is based on the TPM (Total Productive Maintenance) approach and classifies production losses into six categories:
Availability losses: unplanned stoppages, changeover and setup time
Performance losses: minor stoppages and idle time, reduced speed
Quality losses: startup losses, scrap and rework
Measuring OEE — How Does It Work in Practice?
OEE measurement requires three data sources: equipment run time, actual output, and quality data. In practice, this data is often collected manually — with the risk of errors and delays.
Modern OEE systems capture this data automatically via sensors directly at the line, without any intervention in the control system. This reduces effort and delivers real-time data instead of shift reports.
Capture OEE automatically without PLC intervention?
OEE Pilot measures Availability, Performance, and Quality of your production line via IO-Link® sensors1 mounted in parallel with the existing control system. On-premise, from €4,800, 6-week trial available.
- IO-Link is a registered trademark of the PROFIBUS Nutzerorganisation e.V.: io-link.com, profibus.com ↩︎