Single Minute Exchange of Dies (SMED) is kind of like 5-Why’s in that each is not as specific as the name implies. The “5” in 5-Why’s is more a guideline than a specification. Likewise “single minute” is a place-holder for the amount of time that approximates the minimum amount of time it should take for a changeover of production tooling to accommodate a different “model” of the product or service being produced.

SMED is one of many Lean tools that are useful in applying lean rules and principles to process improvements. In the case of SMED, the following Lean principles are invoked:

• Systematic waste elimination
  • Minimized changeover processes mainly target wastes of waiting, motion, transportation
• High agreement as to what and how
  • Changeover processes must be specific and well documented and therefore repeatable with predictable results
• Creating and sustaining a learning organization
  • Pursuit of changeover process improvements entails focused teamwork resulting in learning
• As for the lean rules the following come to mind:
  • Structure every activity
    • Changeover processes must be specific and well documented and therefore repeatable with predictable results
  • Clearly connect every customer and supplier
    • In this case the supplier would be the changeover “team” and the customer would be the production team and/or the actual production machinery and equipment
  • Experiment towards the ideal state
    • SMED techniques promote recurrent application of PDCA-type cycles using “scientific methods” that repeatedly test increasingly more demanding performance targets in the form of hypothesis.

Unlike many productivity improvement initiatives, SMED pursuits usually avoid large capital investments in favor of more “choreographed” activities frequently employing 5S (workplace organization) techniques to speed the changeover and minimize associated production losses.

A great example that I have used in teaching SMED methods is minimizing the amount of time it takes to change a flat tire on a vehicle and get it back on the road. NASCAR pit crews have applied SMED methods over the years to reduce service stops from minutes to seconds. The result is “ballet-like” scenes in the “pits”.

There are a few set of “lenses” used in the SMED process that help focus improvements:

• Reduction or elimination of process steps
• Moving process steps out of the “critical path”
• Doing steps in parallel vs. series
• Small inexpensive tool improvements
• Use of 5S methods to assure the work areas are optimally organized

In short, even where changeovers appear easy and/or short in duration, “There’s gold in them thar hills!” when looking for productivity improvements.