What Is SMED?
SMED (Single-Minute Exchange of Die) is a systematic method developed by Shigeo Shingo for dramatically reducing the time it takes to change a machine from producing one product to producing another. "Single minute" means single-digit minutes — under 10.
Changeover time is pure waste. The machine is not producing. Operators are busy but not making product. Customers are waiting. Every minute of changeover is a minute of lost capacity. Reducing changeover time is one of the fastest ways to improve OEE, reduce batch sizes, and shorten lead times.
The Hidden Factory
A plant running 4 changeovers per day at 45 minutes each loses 3 hours of production daily — that is 15 hours per week, 750+ hours per year. At $500/hour in lost output, that is $375,000 annually from one machine. Use the changeover time calculator to quantify yours.
The Core Insight: Internal vs. External
SMED is built on one powerful distinction:
| Type | Definition | Examples |
|---|---|---|
| Internal Setup | Tasks that can ONLY be done while the machine is stopped | Removing old tooling, installing new tooling, alignment |
| External Setup | Tasks that CAN be done while the machine is still running | Gathering tools, staging next material, preheating, paperwork |
The biggest gains come from recognizing that many tasks currently done with the machine stopped could actually be done while it is still running the previous product. This single insight typically cuts changeover time by 30-50% with zero investment.
The 4 Stages of SMED
Quick Wins (No Investment Needed)
| Action | Typical Time Saved | Effort |
|---|---|---|
| Pre-stage all tools and materials before stopping the machine | 5-15 min | Checklist only |
| Complete paperwork while machine finishes last run | 3-8 min | Process change |
| Assign a second person during changeover | 20-40% | Scheduling |
| Standardize tool locations with shadow boards | 2-5 min | 5S project |
| Create a changeover checklist with step-by-step sequence | 5-10 min | Standard work |
✅ SMED Done Right
- Video the changeover before starting
- Involve the operators who actually do it
- Start with separating internal/external (free gains)
- Standardize the new method and train everyone
- Track changeover time on a control chart
❌ Common Mistakes
- Jumping to equipment purchases before process fixes
- Engineering designs it without operator input
- One-time project with no sustainment
- Only optimizing one changeover type
- No measurement before or after
🎯 Key Takeaway
SMED is the highest-ROI lean tool for most plants. A 50% reduction in changeover time enables smaller batch sizes, shorter lead times, higher OEE, and more flexibility — all from the equipment you already own. Start by videoing your longest changeover, separating internal from external, and you will find 30%+ savings on day one. Use the changeover calculator to quantify the impact.
Changeover Reducer
Click on tasks to move them from internal (machine stopped) to external (done while running). Watch downtime shrink in real time.
Stop reading, start doing
Model your process flow, optimize staffing with Theory of Constraints, and track every shift — all in one platform. Set up in under 5 minutes.