What is SMED (Single-Minute Exchange of Die)?
SMED (Single-Minute Exchange of Die) is a methodology developed by Shigeo Shingo to reduce manufacturing changeover time below 10 minutes. Method: separate internal activities (require stopped equipment) from external (can be done while running), then convert internal to external. Typical result: 50-80% changeover reduction in 6 months.
Origin and history
Shigeo Shingo developed SMED across three projects between 1950 and 1969. The 1950 Mazda project identified internal vs external setup distinction — 50% reduction. The 1957 Mitsubishi project doubled productivity. The 1969 Toyota project on a 1000-ton stamping press reduced changeover from 4 hours to 3 minutes. The ‘Single-Minute’ refers to single-digit minutes (under 10). SMED became globally famous after Shingo’s 1985 book ‘A Revolution in Manufacturing: The SMED System.’
The 4-stage SMED method
Stage 0 — baseline measurement with video and stopwatch. Most plants discover actual changeover is 30-50% longer than believed. Stage 1 — separate internal (stopped equipment required) from external (can be done while running). Most plants find 30-50% of ‘internal’ activities are actually external. Stage 2 — convert internal to external by re-engineering: pre-heat tools, pre-load instruments, pre-position components. Stage 3 — streamline through parallel operations, functional clamps replacing bolts, elimination of adjustments.
Typical SMED results
Manufacturing data across 450+ plants shows: 50-80% changeover time reduction within 6 months. 20-40% Availability improvement in changeover-heavy operations. 3-5 month payback on SMED implementation costs. Permanent process improvement — once internal/external separation is achieved, gains compound rather than decay.
SMED in 2026
Modern SMED implementation is augmented by three tooling categories unavailable in Shingo’s era. Real-time changeover tracking via OEE platforms detects events from machine state transitions. Video analysis with AI activity classification replaces 2-day stopwatch workshops with 1-day smartphone video sessions. Digital work instructions on tablets prevent drift back to old habits.
Frequently asked questions
What does SMED stand for?
SMED stands for Single-Minute Exchange of Die. The ‘single minute’ refers to single-digit minutes (under 10), not literally 60 seconds. Developed by Shigeo Shingo to reduce equipment changeover time.
Who invented SMED?
Shigeo Shingo developed SMED across three projects between 1950 and 1969 — at Mazda (1950), Mitsubishi Heavy Industries (1957), and Toyota (1969). His 1985 book ‘A Revolution in Manufacturing’ introduced it globally.
What are the 4 stages of SMED?
(Stage 0) baseline measurement, (Stage 1) separate internal and external activities, (Stage 2) convert internal to external, (Stage 3) streamline remaining activities through parallel operations, functional clamps, and elimination of adjustments.
Internal vs external setup?
Internal setup requires stopped equipment (removing dies, cleaning fixtures). External setup can be performed while equipment runs (preparing tools, verifying parameters, kitting). SMED converts internal to external.
How much can SMED reduce changeover time?
Typical implementations achieve 50-80% reduction within 6 months. Shingo’s 1969 Toyota project reduced a 1000-ton stamping press changeover from 4 hours to 3 minutes — 98.75% reduction.
When does SMED have biggest OEE impact?
Biggest impact in operations where changeovers are the primary Availability loss: food & beverage, pharmaceutical packaging, multi-product discrete manufacturing. Changeover often accounts for 20-40% of total downtime in these sectors.
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