Single minute exchange of die (SMED)

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Single minute exchange of die (SMED) provides a rapid and efficient way to covert a manufacturing process from running a current product to running the next product in line. The rapid changeover to a new product is part of the lean manufacturing principle, Mura. Mura is aimed at improving the overall flow of production.

Companies that have already implemented a lean manufacturing system should look into SMED as one of their tools. It helps to eliminate unnecessary waste within the company and it aims to improve customer satisfaction. The different with SMED and other lean tools is that it is focused on one small step in the entire manufacturing process, which differs from other concepts that look at is as a whole.

The concept behind SMED arose in the 1950s when Shigeo Shingo, of Toyota, was looking to find a solution to their bottlenecking problems in the car body-molding process. Long change-over times were causing the bottlenecks to occur and were increasing the overall production lot size. If a change-over takes too much time it increases the overall cost of the actual production. Due to high land costs in Japan, Toyota found it difficult to store economic lots of their vehicles. The economic lot size (EQQ) for Toyota cost more than their competitors and Shingo could not find a reasonable solution. SMED was created to reduce costs by implementing smaller lot sizes. Toyota reworked vehicle components to minimize the assembly tools and extra steps in the manufacturing process, thereby reducing change-over times.

Shigeo Shingo created 8 techniques that need to be used if you are implementing SMED:
1. Separate your internal and external operations
2. Convert internal steps to external setup
3. Standardize function instead of shape
4. Use functional clamps and eliminate fasteners altogether
5. Use intermediate jigs
6. Adopt parallel operations
7. Eliminate adjustments
8. Mechanization

There are 4 conceptual stages that also needed to be followed as you implement SMED. First, you must ensure that the external setup applications are performed as the machine is in process. Second, All the internal and external actions need to be separated to ensure that the parts function properly and are efficient in transporting the die and other necessary parts. Third, you must convert internal setup actions to be external ones. Fourth, the final stage is to improve all the setup actions.

SMED is completely focused on reducing changeover. Using the 7 basic steps below, you will begin reducing changeover:
1. Step one is to observe your current methodology and evaluate it.
2. Step two is again to separate the internal and external activities. Your internal activities consist of anything that can be performed when a process is stopped. Your external activities consist of anything that can be done when the process is running.
3. Step three is to convert internal activities to external ones if it is possible.
4. Step four is to streamline all the remaining internal activities to be a simplified process.
5. Step five focuses on streamlining all the remaining external activities to be like the internal ones.
6. Step six is to document the new procedures.
7. Step seven is the final step and that is to repeat steps 1-6 until you see an improvement.

When you begin implementing SMED, you can use additional toolkits to help the process. Some popular toolkits include: visual control, checklists, attachment plates, 5 S Methodology, overhang tools, locating pins, stopper, and other tools.

Remember that SMED is focused on 3 things: internal setup, external setup, and identifying and eliminating wasted motions and non-value-adding activities. SMED is best introduced in additional to other lean manufacturing processes as it corresponds with some of these existing principles.


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