Novent - Digital Lean Production System
Lean Glossary

SMED(Single-Minute Exchange of Dies)

Single-Minute Exchange of Dies (SMED) is a lean manufacturing technique developed to reduce the setup or changeover times for equipment, making it feasible to produce in small lots and increase responsiveness to demand changes. Originating in Toyota's production practices, SMED transformed their production system by enabling quick transitions between products, supporting a shift from large batch production to a leaner, more flexible approach with smaller lot sizes.

The Concept of SMED

Importance of Small Lot Sizes and Quick Setups: In traditional manufacturing, long setup times often justify large batch sizes to maximize machine use and reduce downtime. However, this approach leads to high inventory levels, longer lead times, and less flexibility. SMED allows for small lot production by drastically reducing setup times, so switching from one product to another becomes quick and efficient. As a result, manufacturers can produce a wide variety of products without incurring delays or excessive inventory costs. Toyota’s Setup Time Reduction Journey: In the 1940s, changing dies in Toyota’s presses took two to three hours. By the 1950s, through continuous improvement and production leveling, Toyota reduced setup times to under an hour, reaching as low as 15 minutes. By the late 1960s, setup times had dropped to just three minutes. This reduction made it possible for Toyota to produce small lots of various products quickly, adapting easily to demand changes. Principles of SMED: Separate Internal and External Setup: SMED distinguishes between tasks performed while the machine is running (external setup) and those requiring the machine to be stopped (internal setup). Moving as many tasks as possible to external setup reduces downtime, as preparation can occur before the machine stops. Convert Internal Tasks to External Tasks: Reevaluate processes to shift as many internal tasks as possible to external ones. For example, preparing tools and materials in advance reduces the time the machine must remain idle. Streamline All Aspects of Setup: SMED encourages simplifying and standardizing each part of the setup process. Standard tools, quick-release mechanisms, and pre-measured adjustments can streamline changeovers and reduce errors. Benefits of SMED: Flexibility for Small Lot Production: With shorter setup times, small lot production becomes feasible, allowing manufacturers to respond quickly to demand fluctuations. Reduced Inventory: Faster changeovers mean less need for large batches or buffer stock, reducing inventory costs and freeing up space. Decreased Downtime: Shortening setup times minimizes downtime and maximizes productive machine time, making the most of available equipment. Enhanced Responsiveness: By enabling quick changeovers, SMED allows for greater product variety and faster response to customer needs without compromising efficiency.

Implementing SMED

Observe and Document Current Setup Procedures: Begin by understanding and documenting the current setup process, noting all tasks performed while the machine is stopped. This helps identify tasks that could be shifted to external setup. Separate Internal and External Setup Tasks: Classify each task as internal or external, moving any feasible tasks to external setup. Simplify Internal Setup Tasks: Look for ways to streamline the tasks that must be done while the machine is stopped. This may include using quick-release mechanisms, color-coded tools, or other aids that reduce adjustment time. Test and Refine the Process: Practice the new setup process, involving operators in testing and refining it. Continuous improvement is key to achieving the quickest possible setup times.

Conclusion

SMED revolutionizes manufacturing by enabling fast changeovers and supporting small lot production. By reducing setup times, manufacturers can produce with more flexibility, adapt to diverse product demands, and minimize inventory costs. This lean technique is essential for creating a responsive, efficient production environment that aligns with real customer needs.