The encyclopedia · Engineering & Operations · Operational decision · 1950–1969
Shingo cut Toyota's 1000-ton die change from 4 hours to 3 minutes with SMED
Shigeo Shingo separated setup into internal and external work, so Toyota cut a 1000-ton die change from 4 hours to under 10 minutes.
Toyota Motor Corporation
the move
Shigeo Shingo developed SMED—Single-Minute Exchange of Die—across three projects between 1950 and 1969: Mazda (1950) revealed the internal/external setup distinction and halved setup; Mitsubishi (1957) doubled productivity; and Toyota (1969) took a 1000-ton stamping press from four hours to three minutes.
The name means single-digit minutes, under ten, not sixty seconds. The method: measure and separate activities that require a stopped machine (internal) from those that can happen while it runs (external); convert internal work to external by pre-heating, pre-loading and pre-positioning; then streamline the remainder with parallel work, functional clamps and eliminating adjustments.
Because changeover no longer ate hours, factories could run small batches economically—the operational foundation for just-in-time production. Shingo's 1985 book 'A Revolution in Manufacturing: The SMED System' carried the method worldwide, where typical implementations cut changeover time 50–80% within months.
why it works
- Setup had been treated as fixed downtime, so plants over-produced to amortize it.
- Separating internal from external work exposed that much 'setup' never needed the machine stopped.
- Pre-staging tools and dies converted stopped time into running time.
- Small batches cut inventory and let production follow demand instead of forecasts.
what transfers
Most changeover time is waste you can move out of the machine's downtime: separate, convert, then streamline—small batches and flexible scheduling follow for free.
what came after
SMED became a standard pillar of lean manufacturing alongside kanban and TPM, applied across automotive, food, pharma and packaging; the 2019 literature review counts over 130 published SMED studies, and changeover reduction remains a core equipment-effectiveness lever in factories worldwide.
references
- Single-minute exchange of die (SMED): a state-of-the-art literature review
- What is SMED? Single-Minute Exchange of Die
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