SMED (Single-Minute Exchange of Die) is a lean method for reducing changeover time. In garment factories it applies to style changeovers: the time from the last good piece of the old style to the new style reaching its target.
The key idea
Split changeover work into two types:
- Internal: can only be done when the line has stopped the old style (changing a folder on the machine in use).
- External: can be done while the old style is still running (preparing machines, attachments, trims, training operators, printing the new bulletin).
Most delays come from doing external work after the old style ends.
Steps
- Record a real changeover and list every task with its time.
- Separate internal and external tasks.
- Move as much as possible to external - prepare it before the change day.
- Simplify internal tasks: pre-set attachments, quick-change guides, a standard machine layout.
- Standardise with a changeover checklist used for every style.
A changeover checklist
| Before the change day | On the change day |
|---|---|
| New bulletin, SAM and layout ready | Move machines to the new layout |
| Extra machines and attachments arranged | Fit and test attachments |
| Operators trained on new operations | Pilot run and first-piece approval |
| Trims and cut work ready at the line | Check hourly output against the ramp-up plan |
Tip: Plan changeovers on a calendar at least two weeks ahead, with a readiness percentage for each one, so problems are found early.