Shingo cut Toyota's 1000-ton die change from 4 hours to 3 minutes with SMED

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.

Do most setup while the machine still runs

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.

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.

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.