Overall equipment effectiveness
How much good output a line produced compared with what it could have produced running perfectly.
01 What it is
Why anyone looks at this number
How much good output a line produced compared with what it could have produced running perfectly.
It turns "the factory is busy" into a number, and it separates the three very different reasons capacity disappears: downtime, slow running and scrap.
02 The formula
How it is worked out
Overall equipment effectiveness = availability × performance × quality grain : shift × line unit : percentage source : MES or line-side data capture
Agree what counts as planned time. Excluding planned maintenance and changeovers is normal, but the exclusion list is the entire argument — write it down.
03 Worked example
The same number, with real inputs
| Availability | 88% |
| Performance | 92% |
| Quality | 97% |
| Calculation | 0.88 × 0.92 × 0.97 |
| Result | 78.5% |
One fifth of capacity is gone. The speed loss alone is worth more than most capex proposals, and costs nothing to investigate.
04 What moves it
Four things that actually change this number
Downtime
Breakdowns, changeovers, waiting for material or people.
Speed losses
Running below the design rate, usually unnoticed and continuous.
Quality losses
Scrap and rework, including start-up waste after every changeover.
Product mix
Some products simply run slower than the design product.
05 Where the number lives
The system, the record and the fields
| System of record | Key record | Fields you need |
|---|---|---|
| MES or line-side data capture | Work order and Asset / Line | planned_time, downtime, ideal_cycle_time, total_count, good_count |
Agree what counts as planned time. Excluding planned maintenance and changeovers is normal, but the exclusion list is the entire argument — write it down.
06 How it goes wrong
Three ways this metric misleads people
Comparing OEE between lines
Different products and design speeds make the comparison meaningless.
Fix: Compare a line against itself over time.Chasing the number
Running long batches of easy product raises OEE and destroys service.
Fix: Report it beside schedule adherence and stock.Hiding losses in planned time
Everything inconvenient gets reclassified as planned and OEE improves on paper.
Fix: Fix the planned-time definition and audit changes to it.08 Questions
Frequently asked
What is world-class OEE?
Around 85% is the figure usually quoted for discrete manufacturing, but it depends heavily on the process. The three components matter more than the headline.
Should OEE include changeovers?
If changeovers are a genuine constraint on your capacity, include them — otherwise you optimise the number by making fewer, longer runs, which hurts service.
One definition, everywhere it is used
SCIKIQ stores this metric once and serves it to every dashboard, board pack and agent that asks.