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What Is OEE and Why Every Maintenance Team Should Track It
2025-03-10Vallejo Reliability Group

What Is OEE and Why Every Maintenance Team Should Track It

OEEKPIsMaintenance

What Is OEE?

Overall Equipment Effectiveness (OEE) is the gold standard metric for measuring manufacturing productivity. It tells you what percentage of planned production time is truly productive.

OEE = Availability × Performance × Quality

| Component | Formula | What It Measures | |---|---|---| | Availability | Run Time ÷ Planned Production Time | Downtime losses | | Performance | (Ideal Cycle Time × Total Count) ÷ Run Time | Speed losses | | Quality | Good Count ÷ Total Count | Quality losses |

A World-Class OEE Score

An OEE of 85% is considered world-class for discrete manufacturing. Most plants average between 40–60%.

The Three Loss Categories

1. Availability Loss

  • Equipment downtime from breakdowns, setup, and changeovers
  • Target: >90% availability

2. Performance Loss

  • Speed reduction due to minor stops, slow cycles
  • Target: >95% performance

3. Quality Loss

  • Defects and scrap from the process
  • Target: >99% quality

Why It Matters for Maintenance

OEE directly reflects the impact of maintenance decisions. Poor availability drags down OEE — and poor maintenance strategy drives poor availability.

Real-World Example

A bottleneck assembly line:

  • Planned production time: 480 minutes/day
  • Actual run time: 360 minutes (downtime: 2 hours)
  • Good output: 540 units (expected: 600 units)

Availability = 360 ÷ 480 = 75% Performance = 600 ÷ 540 = 90% Quality = 540 ÷ 600 = 90% OEE = 0.75 × 0.90 × 0.90 = 60.75%

This plant has room for significant improvement by reducing downtime.

🏆 Track OEE at the asset level, not just the plant level. A single bottleneck machine with 55% OEE can tank overall plant throughput.