SMED is a structured setup-reduction method that aims to reduce changeovers to single-digit minutes by separating, converting, and streamlining setup work.
Definition
Single Minute Exchange of Die (SMED) is a Lean method for reducing changeover time. Single minute means single-digit minutes, not necessarily one minute. The method separates internal setup work that must occur while equipment is stopped from external work that can happen while it is running.
SMED improves flexibility, lowers batch pressure, reduces inventory, and supports flow.
History
SMED is associated with Shigeo Shingo and Toyota Production System development. It challenged the assumption that long setups were unavoidable and enabled smaller lots, faster response, and lower inventory.
When to Use
Use SMED when setup time drives large batches, low responsiveness, high inventory, schedule difficulty, startup scrap, or changeover avoidance. It applies to dies, molds, fixtures, recipes, software deployments, test setups, and administrative handoffs.
Step-by-Step
- Select a high-impact changeover and define timing boundaries.
- Observe or record the full setup safely.
- Separate internal from external tasks.
- Convert internal tasks to external tasks where practical.
- Streamline remaining internal work with clamps, guides, kits, parallel work, and mistake proofing.
- Reduce adjustment and trial runs through standards and settings.
- Create setup standard work and visual controls.
- Track setup time, startup quality, and sustainment.
Examples
- Stamping: Pre-staged dies and quick clamps reduce press downtime.
- Injection molding: Standard connections and preheated molds shorten changeover.
- Packaging: Preset guides and verified recipes reduce adjustment loops.
Common Pitfalls
- Focusing only on tool changes and ignoring staging, waiting, or first-good-part time.
- Unsafe parallel work.
- No measurement of startup scrap.
- Improvement without standard setup sequence.
- Missing maintenance or tooling condition issues.
- Failure to audit setup readiness.