Internal setup vs external setup
SMED's entire method comes down to one split. Internal setup is work that can only happen with the machine stopped — swapping a fixture, pulling a tool, dialing in an offset. External setup is everything that can be done while the machine is still running the previous job — staging the next tool, pre-setting an offset on a second holder, pulling the next program up.
Most changeovers, left alone, treat almost everything as internal by habit — the operator starts looking for the next tool only after the machine stops. SMED’s move is just forcing that question: for each step in the changeover, does it actually require the machine to be stopped, or has it always been done that way?
A worked example
A changeover that currently runs 45 minutes, broken into its real steps:
- 12 min — walk to the tool crib, find the next tool set
- 18 min — remove old fixture, mount new fixture
- 10 min — dial in offsets, run first-off
- 5 min — paperwork, program selection
Moving the tool search and paperwork to before the machine stops — while the previous job is still running — removes 17 minutes without touching the physical fixture swap at all. 45 minutes becomes 28 from reclassification alone, before any work on the fixture-swap step itself.