The Six Big Losses
The Six Big Losses map every production loss to OEE's three factors. Learn what each one is, how to spot it, and where to attack first.
The Six Big Losses are the six ways manufacturing equipment wastes time and material - two each for availability, performance and quality. They come from TPM (Total Productive Maintenance) and they map one-to-one onto the three OEE factors, which is what makes OEE so actionable: a low factor points straight at the losses behind it.
Availability losses
1. Breakdowns (equipment failure)
Unplanned stops where the equipment can't run - a failure, a fault, a tool change after a break. Usually the most visible loss and the first one teams chase. Attack it with reliability and maintenance work: spot the machines and failure modes that recur, and prevent them.
2. Setup & adjustments (changeovers)
Time lost switching from one product or batch to the next - changeover, cleaning, warm-up, first-article checks. High-mix lines lose enormous time here. The classic remedy is SMED (Single-Minute Exchange of Die): convert setup steps that currently stop the line into ones you can do while it still runs.
Performance losses
3. Idling & minor stops
Short stoppages - a jam, a misfeed, a blocked sensor, a brief starve - cleared by an operator in seconds or a couple of minutes. Individually trivial, collectively huge, and almost always invisible on manual logs because nobody writes down a 40-second stop. This is the loss automatic capture exposes first.
4. Reduced speed
The line runs, but slower than its ideal cycle time - a worn part, a cautious operator, a derate to avoid jams. Reduced speed hides in plain sight because the line looks like it's running. It only shows up when you measure actual rate against the nameplate rate.
Quality losses
5. Production defects
Scrap and rework produced while the process is running steadily. Anything that needed a second pass is a defect - rework is not free. Attack it with process control and mistake- proofing at the source.
6. Startup & yield losses
Defects from startup until the process stabilises - warm-up rejects, the scrap before a line settles after a changeover. Reduce it by stabilising startups and tightening changeover quality (which ties straight back to loss 2).
Where to attack first
Don't try to fix all six at once. Measure honestly, rank the losses by the time and money they actually cost, and start with the vital few - most plants find a handful of causes drive the majority of loss. That Pareto-first method is exactly what the reduce-downtime playbook walks through.
Key takeaways
- Six losses, two per OEE factor: breakdowns & setup (availability); minor stops & reduced speed (performance); defects & startup losses (quality).
- Minor stops and reduced speed are the most under-measured - and often the biggest.
- SMED attacks changeover loss; reliability work attacks breakdowns.
- Rank losses by cost and fix the vital few first, rather than spreading effort across all six.