OEE and the Six Big Losses: The Original Categories That Built the Metric

Key takeaways

• The six big losses from TPM map to the three OEE factors: 2 to Availability, 2 to Performance, 2 to Quality.
• Availability losses: equipment failure, setup and adjustment.
• Performance losses: idling and minor stops, reduced speed.
• Quality losses: defects in process, reduced yield at startup.
• Plants that know which of the six is dominant for each line attack the right problem. Plants that track only OEE without decomposing the six see the symptom but miss the cause.

Short answer: The six big losses are the original loss categories TPM identified that prevent ideal equipment performance. OEE was built to measure them. The six map to the three OEE factors. Availability (failures, setup), Performance (minor stops, reduced speed), and Quality (defects, startup yield).

Knowing which of the six is dominant per line is the operational signal OEE delivers; treating OEE as a single number without the six-loss breakdown misses the point. See also OEE vs Utilization .

The six big losses

1. Equipment failure (Availability loss). Unplanned downtime from breakdowns. The most visible loss because the line is obviously stopped.

2. Setup and adjustment (Availability loss). Time spent between SKUs, changeover, tooling change, line clear. Often the largest Availability loss in high-mix plants.

3. Idling and minor stops (Performance loss). Pauses under the downtime logging threshold, jam clears, material delays, brief interventions. Invisible to most monitoring; eats Performance.

4. Reduced speed (Performance loss). Line is running but below design rate. Slow cycles from tool wear, recipe drift, or aging equipment. Often the biggest hidden loss.

5. Defects in process (Quality loss). Bad parts produced during steady-state run. Scrap, rework, out-of-spec output.

6. Reduced yield at startup (Quality loss). First-piece losses at the beginning of a run, after changeover, or post-restart. Often bucketed as "planned waste" but it is real Quality loss.

How the six map to OEE

OEE = Availability x Performance x Quality, and each factor captures two of the six:

• Availability = (Planned production time - Loss 1 - Loss 2) / Planned production time.
• Performance = (Run rate / Design rate), captures Loss 3 and Loss 4.
• Quality = (Good parts / Total parts), captures Loss 5 and Loss 6.

The six are how TPM defines the losses; OEE is how the math aggregates them.

Which loss is usually dominant

Highly dependent on plant type:

• Discrete, high-mix: setup and adjustment (Loss 2) typically dominates.
• Discrete, low-mix: equipment failure (Loss 1) or reduced speed (Loss 4) dominates.
• Process / batch: reduced yield at startup (Loss 6) and setup (Loss 2) typically dominate.
• High-tech / automated: idling and minor stops (Loss 3) often dominate because the equipment is reliable but micro-stops accumulate.

Plants assuming their dominant loss without measuring usually guess wrong.

How to act on the six big losses

Each loss has a different countermeasure:

• Loss 1 (failures): reliability work. RCM, PM optimization, condition monitoring.
• Loss 2 (setup): SMED, separate internal from external, streamline.
• Loss 3 (idling and minor stops): log finer, observe directly, eliminate causes (jams, material flow).
• Loss 4 (reduced speed): recipe verification, tool conditioning, operator standardization.
• Loss 5 (defects in process): SPC, root cause analysis, Poka-Yoke.
• Loss 6 (startup yield): first-piece confirmation procedures, recipe pre-validation, startup parameter optimization.

One countermeasure per loss. The mistake is to apply the wrong countermeasure because the loss was not decomposed.

Common mistakes

1. Treating OEE as one number. Hides which of the six is the actual problem.

2. Bucketing Loss 6 as "planned waste." Startup scrap is real Quality loss. Hide it and you cannot fix it.

3. Ignoring Loss 3. Minor stops are individually small but compound. Plants that do not log micro-stops have an inflated run time and a depressed Performance.

4. Applying SMED to a plant where failures dominate. Wrong countermeasure for the wrong loss.

How a modern OEE platform shows the six losses

A modern platform decomposes OEE into the six losses automatically: time and percentage attributed to each, with drill-down to the underlying events. The output is a Pareto of losses with countermeasure recommendations.

Fabrico's OEE module surfaces the six-loss Pareto per line and per shift, with click-through to the underlying events, pointing the team at the dominant loss with the right countermeasure direction.

See how Fabrico captures this automatically, explore OEE for manufacturing or book a demo.

Related reading

• OEE vs Utilization
• OEE and ISO 22400
• OEE for Batch Manufacturing
• OEE vs Availability

Frequently asked questions

Are there more than six losses?

Some frameworks extend to eight or sixteen losses (adding management losses, planning losses, etc.). The six are the original TPM set and remain the most widely used.

Is "no production scheduled" a big loss?

No. It is excluded from OEE because it is intentional. TEEP (Total Effective Equipment Performance) includes it; OEE does not.

How do I tell idling from reduced speed?

Idling is brief pauses; reduced speed is sustained slow operation. Cycle-time distribution per shift separates them.

Where do safety stops fit?

Typically Loss 1 (unplanned downtime). Some plants track them separately to emphasize importance.

Are there "big losses" outside OEE?

Yes. Material losses, energy losses, labor losses, these are not in OEE but matter for overall plant performance.