Key facts
- What it measures: overall equipment effectiveness (OEE) = availability x performance x quality.
- Where it comes from: total productive maintenance (TPM), which uses OEE to rank equipment losses.
- Best used on: one machine, line or constraint, compared with its own history rather than another plant.
- Cadence: reviewed every shift or day at the line, and trended weekly or monthly.
Why does OEE matter to a manufacturing team?
- It makes hidden losses visible. A line that "runs all day" can still lose time to small stops, slow cycles and scrap. OEE puts a number on each.
- It points effort at the biggest loss. Splitting the result into availability, performance and quality shows which of the six big losses to attack first.
- It gives one shared language. Operators, maintenance and supervisors look at the same measure instead of arguing about whose numbers are right.
- It can free capacity. Recovering lost time on an existing machine can add output without buying another one.
- It supports daily management. A visible OEE trend on the tier board gives the team something concrete to review at the start of each shift.
How is OEE calculated?
| Factor | Question it answers | Typical losses |
|---|---|---|
| Availability | Was the machine running when it should have been? | Breakdowns, changeovers, waiting for material |
| Performance | Did it run at full speed? | Small stops, reduced speed |
| Quality | Was the output right first time? | Start-up rejects, scrap, rework |
Multiply the three results together. For example, 90% availability, 95% performance and 98% quality gives an OEE of about 84%.
What should you watch out for?
OEE is a diagnostic, not a target to chase. A high number can hide a poor process if the ideal cycle time is set too generously, and comparing different machines or plants rarely means much because each defines losses differently. Agree the definitions first, then track the trend and the reasons behind each loss. See total productive maintenance for how the six big losses are tackled.
Example
A packaging line records an OEE of 62%. Splitting the figure shows availability is the weak point, mostly from changeovers. The team works on standard work for changeovers and moves tool preparation ahead of the stop. Availability rises over the next few weeks, and the line trend shows the gain holding.