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amarpreet41
- December 22, 2025
What is OEE?
OEE shows what percentage of your planned production time is truly productive.
- 100% OEE means: running all planned time, at maximum speed, making only good boards.
- In real SMT lines, typical OEE is far below 100% because of changeovers, stoppages, speed losses and defects.
Formula: OEE = Availability × Performance × Quality (all as percentages).
Step 1 – Calculate Availability (SMT Example)
Availability looks at: “Out of the planned time, how much time did the line actually run?”
Formula:
- Availability = Run Time / Planned Production Time.
SMT example – Pick & Place line
- Shift length: 8 hours = 480 minutes.
- Planned breaks: 30 minutes.
- Planned production time = 480 − 30 = 450 minutes.
- Unplanned stops:
- 20 min for feeder jam.
- 10 min for printer cleaning due to paste smear.
- 20 min waiting for components.
- Total unplanned stop = 50 minutes.
Run Time = 450 − 50 = 400 minutes.
Availability = 400 / 450 = 0.8889 → 88.9%.
Step 2 – Calculate Performance (SMT Example)
Performance asks: “When the line was running, did it run at the designed speed?”
Formula (recommended):
- Performance = (Ideal Cycle Time × Total Count) / Run Time.
Where:
- Ideal Cycle Time = fastest possible time per board at rated CPH.
SMT example – Same line
Assume:
- Ideal line rate = 3,600 CPH (1 board per minute).
- So Ideal Cycle Time = 1 minute per board.
- During the 400 minutes of Run Time, the line produced 320 boards (good + bad).
Performance = (Ideal Cycle Time × Total Count) / Run Time = (1 × 320) / 400 = 0.8 → 80%.
This 20% loss could be from: micro‑stoppages at printer, slow placement due to conservative speed, manual interventions, etc.
Step 3 – Calculate Quality (SMT Example)
Quality asks: “Of all boards produced, how many passed without rework?”
Formula:
- Quality = Good Count / Total Count.
SMT example – Same lot
- Total boards produced: 320.
- Boards that failed AOI or functional test and need rework: 16.
Good Count = 320 − 16 = 304 boards.
Quality = 304 / 320 = 0.95 → 95%.
Step 4 – Calculate OEE for the SMT Line
Now multiply the three factors:
- Availability = 88.9% → 0.889
- Performance = 80% → 0.80
- Quality = 95% → 0.95
OEE = 0.889 × 0.80 × 0.95 ≈ 0.676 → 67.6%.
This means the SMT line is only 67.6% effective compared to its full potential over that shift.
Here is a detailed presentation on how to calculate OEE in any manufacturing Industry.