Manufacturing ·
How to measure OEE without new machines
What OEE is, how to calculate it with a worked example and how to measure it on older machines without PLCs.
OEE (Overall Equipment Effectiveness) is one number that shows how much of your planned capacity you actually use. The good news: you don’t need new machines to measure it.
The formula
OEE = Availability × Performance × Quality.
- Availability — how much of the planned time the machine actually ran.
- Performance — how fast it ran compared with the ideal cycle time.
- Quality — how much of the output was good first time.
Worked example
| MEASURE | VALUE |
|---|---|
| Planned time | 480 min |
| Downtime | 48 min |
| Run time | 432 min → availability 90% |
| Ideal cycle | 1 min per part |
| Produced | 380 parts → performance 88% |
| Good parts | 370 → quality 97.4% |
| OEE | 0.90 × 0.88 × 0.974 ≈ 77% |
85% is often quoted as “world class”, but what matters more is knowing your own number and seeing it rise.
Measuring older machines
- A current sensor on the power supply — shows whether the machine is running, without touching the controls.
- A pulse counter on the output — counts parts.
- A barcode at the end of the line — every part or pack is scanned.
- A tablet by the machine — the operator picks the downtime reason with one tap.
Common mistakes
- Measuring only availability — speed and scrap stay hidden.
- Downtime reasons written at the end of the shift, from memory.
- Too many reasons to choose from — operators pick “other”.
- Numbers nobody looks at — the dashboard must be visible on the floor.
Start with a pilot on one line — within weeks you’ll know where the time goes. More about machine monitoring and OEE →