Production and OEE
What is Six big losses?
The six big losses are the main causes of lost productive time behind OEE: breakdowns, setups, small stops, slow cycles, production rejects and startup rejects.
Quick answer
The six big losses are the most common causes of lost productivity in manufacturing, grouped by the OEE factor they reduce. Availability: unplanned stops and planned stops such as changeovers. Performance: small stops and slow cycles. Quality: production rejects and startup rejects. Tracking them shows where OEE is lost.
Updated 30 October 2026. Written by the Ajinkya Technologies engineering team, reviewed by Amey Kadle.
Six big losses explained
The framework comes from total productive maintenance (TPM), associated with Seiichi Nakajima at the Japan Institute of Plant Maintenance. It turns a single OEE percentage into six buckets that point to different fixes.
Availability losses are unplanned stops (equipment failure, material shortage, no operator) and planned stops that are still losses, chiefly setups, changeovers and adjustments. Reliability work and maintenance reduce the first; changeover reduction methods such as SMED reduce the second. Performance losses are small stops, usually under a few minutes and often not logged by operators, and slow cycles, where the machine runs below its ideal rate because of wear, material or cautious settings. Quality losses are production rejects during steady running and startup rejects after a changeover or restart until the process stabilises.
Small stops and slow cycles are the losses manual logs miss most, because no single event feels worth writing down. Automatic data collection from the machine counts every stop and every cycle, and is usually where plants find the largest gap between reported and real OEE.
Key concepts
- Availability: unplanned stops, setups and adjustments
- Performance: small stops, slow cycles
- Quality: production rejects, startup rejects
- Comes from total productive maintenance (TPM)
- Automatic capture finds the hidden losses
How to start tracking the six big losses
- 1
Agree definitions
Write down what counts as planned time, a small stop and a reject so every shift classifies the same way.
- 2
Capture stops automatically
Take run, stop and count signals from each machine so short stops and slow cycles are recorded without operator effort.
- 3
Add reason codes for longer stops
Ask operators for a reason only for stops longer than a threshold, using a short list they helped write.
- 4
Review a loss Pareto weekly
Rank losses by minutes or cost and fix the largest one before adding more data.
Questions
What are the six big losses?
Unplanned stops, planned stops (setups and adjustments), small stops, slow cycles, production rejects and startup rejects.
Which loss is usually the biggest?
It varies by plant, but small stops and slow cycles are the most underreported because operators rarely log them. Automatic capture often shows they are larger than breakdowns.
Are changeovers a loss if they are planned?
In OEE, yes. Planned production time includes changeovers, so they reduce availability. That makes changeover reduction visible as an OEE improvement.
References
How we help with six big losses
Our downtime and OEE systems classify every stop into the six big losses automatically from machine signals, and ask operators for a reason only where it matters.
Free OEE calculator; add your email to see what your losses cost each month.
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