The six big losses are TPM’s classic categorisation of equipment losses: (1) breakdowns, (2) changeover and adjustment, (3) minor stops, (4) reduced speed, (5) start-up defects and (6) process defects/scrap. The three pairs correspond to OEE’s three factors: availability, performance and quality.
The point of the categorisation is that different losses require different countermeasures: breakdowns require preventive maintenance, changeovers require SMED, minor stops require root-cause hunting on the floor — a single overall “waste percentage” hides where the effort should go.
Minor stops and reduced speed are the most often underestimated losses, because they are rarely recorded: 30 seconds here and there is booked nowhere, but sums to hours per week.