TeamAssurance

    What is SMED?

    Short answer

    SMED, single-minute exchange of die, is the lean method for reducing changeover time, developed by Shigeo Shingo at Toyota. The aim is to get changeovers into single-digit minutes by separating the setup work that must be done with the machine stopped (internal) from work that can be done while it runs (external), converting internal to external, and streamlining what remains.

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    Why changeover time matters

    Long changeovers push operations toward large batches, which create inventory, hide defects and lengthen lead times. Shortening changeovers makes small batches economic, so production can follow demand. SMED is also one of the six big losses in OEE: set-up and adjustment.

    The SMED steps

    1. Observe and record the current changeover. Video it; list every step with its time and whether the machine was stopped.
    2. Separate internal and external work. Internal steps need the machine stopped; external steps (fetching tools, preparing the next die, paperwork) can happen while it runs.
    3. Move external work out of the stop. Prepare everything before the machine stops. This alone often halves the changeover.
    4. Convert internal work to external. Pre-heat, pre-set, use standardised fixtures and quick-release clamps so adjustment happens off the machine.
    5. Streamline what remains. Parallel tasks, eliminated adjustments, marked settings, standard work for the changeover itself.
    6. Standardise and train, then measure every changeover against the new standard.

    A worked example

    A packing line changeover took 55 minutes. Recording it showed 20 minutes finding and fetching parts (external), 15 minutes of adjustment by trial (internal, convertible with marked settings), and 20 minutes of genuine internal work. After SMED: parts staged on a cart before the stop, settings marked, two people working in parallel on defined tasks. Changeover: 14 minutes.

    Sustaining SMED

    Changeover time is a measure for the tier board: each changeover against the standard, with reasons for any overrun. Drift shows within a week and becomes a problem to solve rather than a slow return to the old way.

    Common mistakes

    • Buying equipment before doing the first three steps.
    • Treating SMED as a one-off event instead of a standard that is audited.
    • Not involving the operators and setters who do the changeover.

    How TeamAssurance helps

    TeamAssurance tier boards can track changeover time against the standard for each line with the reason for every overrun, so the Tier 1 huddle sees drift immediately. The changeover standard is a mobile checklist with the staged-parts and settings steps, and chronic overruns move into A3 problem solving in the continuous improvement capability.

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    Frequently asked questions

    Does single-minute mean under one minute?

    No. It means a single-digit number of minutes, under ten. Many operations use SMED to cut changeovers from hours to tens of minutes without reaching single digits, which is still a large gain.

    What is the difference between internal and external setup?

    Internal setup can only be done with the machine stopped, such as removing and fitting a die. External setup can be done while the machine runs, such as fetching tools or preparing the next die. SMED moves as much work as possible to external.

    How does SMED relate to OEE?

    Set-up and adjustment is one of the six big losses that reduce availability in OEE. Reducing changeover time raises availability directly and allows smaller batches, which reduces other losses too.

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