Single-Minute Exchange of Die (SMED)

Introduction: SMED

Single-Minute Exchange of Die (SMED) is a Lean manufacturing method developed by Shigeo Shingo to reduce machine changeover times. Its objective is to complete changeovers in less than ten minutes (single-digit minutes), thereby reducing downtime, increasing efficiency, and enabling more flexible production.

Background

In traditional mass production, long changeover times often led to large batch sizes and high inventory levels. Shingo introduced SMED as part of the Toyota Production System to make production more responsive to customer demand. By reducing setup time, organisations can achieve just-in-time production, smaller batches, and reduced waste.

Key Elements/Features

• Separation of setup times:
  • Internal setup – tasks performed only when the machine is stopped (e.g., replacing a die).
  • External setup – tasks completed while the machine is running (e.g., preparing tools).
• Convert internal to external: Shift as many tasks as possible to external setup to minimise downtime.
• Streamline activities: Standardise components, use quick-release mechanisms, and train staff in efficient techniques.

Applications/Examples

SMED can be implemented through:

1. Documenting the current process: Recording each step of a changeover.
2. Classifying activities: Identifying internal versus external tasks.
3. Converting tasks: Moving suitable internal tasks to external.
4. Optimising remaining steps: Simplifying and accelerating essential internal activities.
5. Standardising the new method: Creating standard procedures and training staff.

For example, in an automotive plant, changeovers that once took hours can be reduced to minutes, allowing rapid shifts between different models without halting production flow.

Relevance/Impact

SMED reduces downtime, lowers costs, and increases flexibility by enabling smaller batches and faster response to market changes. It is a cornerstone of Lean manufacturing, making processes more adaptable, efficient, and customer-focused.

See also

• Quick Change-over
• Standardised Work
• Just-in-Time (JIT)
• Overall Equipment Effectiveness (OEE)