How should downtime reasons be classified?
How to build a reason list people actually use, and why “other” is dangerous.
Why the list matters
Downtime data is only as good as its reason list. Too long, and operators pick the first thing they see; too short, and losses blur together. A good list is one a person on the floor can use correctly in a few seconds.
Two levels are enough
Two levels work on most floors: first a class, then a reason.
- Breakdown: mechanical, electrical, tooling
- Setup: changeover, adjustment
- Material: waiting for material, wrong material
- Quality: waiting for inspection, quality stop
- Planned: break, meeting, planned maintenance
The “other” option
“Other” is the most dangerous option on the list: after a while it becomes the largest loss class and teaches nothing. If you cannot remove it, require a short note, and review it regularly to turn entries into new reasons.
Rules that make it stick
A few simple rules keep the list alive:
- Build the list together with operators.
- Do not show too many options at once; filter by work center.
- Discuss the top three reasons with the team each month.
- Remove reasons nobody uses.
See your own numbers.
Work out the yearly value of your losses in a minute, or talk to us about your floor.