Lean Manufacturing and Six Sigma Definitions

Glossary terms, history, people and definitions about Lean and Six Sigma


Abbreviation for Single Minute Exchange of Dies, which is a process of reducing changeover (setup) time by classifying elements as internal or external to a machine’s operating time and then converting the internal elements so they can be done externally (while the machine continues to operate). The goal is to reduce the setup time from hours down to less than 10 minutes (9 minutes or less, thus the single minute concept). Although not every setup can literally be completed in single-digit minutes, this is the goal, and it can be achieved in a high percentage of cases.

Developed by Shigeo Shingo to reduce the set-up time (change of dies) of pressing machines. He was able to shorten set-up times from 1 to 2 hours (or even half a day) per each exchange of dies to only a few minutes each, allowing an organization to run smaller batches and align more closely to customer demand.

The key to success is to move as many setup tasks from internal setup to external setup, then reduce the time needed to complete the internal tasks.

Internal setup – can only be performed when the machine is down
External setup – can be performed when the machine is running

Shigeo Shingo said that between 1975 and 1985, average setup times he has dealt with have reduced to 2.5% of the time originally required; a 40 times improvement. [A Revolution in Manufacturing: The SMED System, by Shigeo Shingo]

Ritsuo Shingo, son of Shigeo, mentioned in a 2021 interview that the origins of SMED were based on Shigeo’s love of golf, where having a single digit handicap was considered excellent. After coming up with SMED, it was later determined that Single Digit Exchange of Die (SDED) might be a better translation instead of implying that it needs to be a one minute setup time, but it was too late, SMED had already caught on as a term.

Shingo recognizes eight techniques that should be considered in implementing SMED.

  1. Separate internal from external setup operations
  2. Convert internal to external setup
  3. Standardize function, not shape
  4. Use functional clamps or eliminate fasteners altogether
  5. Use intermediate jigs
  6. Adopt parallel operations (see image below)
  7. Eliminate adjustments
  8. Mechanization

Closely associated to SMED, but a more difficult concept is OTED.

Here is the set up reduction (SUR) progress over the years in car racing pit stops.