SMED Changeover

Convert internal setup work to external, streamline the rest, and cut changeover from hours to minutes.

Time1 h 30
FormatTeam
StageMake

SMED Changeover: what it is and why it works

SMED, or Single-Minute Exchange of Die, is a method for reducing changeover time, the time from the last good part of one product to the first good part of the next. Its core idea is to separate setup work into internal activities, which can only be done while the machine is stopped, and external activities, which can be done while it is still running. A changeover is recorded on video and broken into steps, each step is classified, and as much internal work as possible is converted to external through preparation, pre-staging and pre-heating. The remaining internal work is then streamlined using standardized fixtures, quick clamps, one-turn fasteners, eliminated adjustments and parallel work by two people.

SMED works because a large share of typical changeover time is spent searching, fetching, waiting and adjusting, not on the exchange itself. Shortening changeovers adds capacity on busy machines and, more importantly, makes smaller batches economical. Smaller batches reduce inventory, shorten lead time and allow more frequent production of each product, which supports level scheduling. The name refers to aiming for changeovers under ten minutes, a single-digit number; not every process reaches that, but repeated rounds usually bring large improvements. SMED often follows an OEE analysis showing setup as the largest availability loss and matters most on the constraint identified with Theory of Constraints.

What you need

A video of one complete changeover from last good part to first good part
The operators, setup technicians and a maintenance person who perform changeovers
Current changeover times and frequencies from production records
Site safety rules for work on stopped machines, including lockout/tagout where required

What you get

A step-by-step changeover analysis with times and internal or external classification
A list of steps converted to external and the preparation standard supporting them
Streamlining actions for remaining internal steps, such as fixtures or quick connects
A new standard work sheet and target changeover time

When to use it

When small batches are uneconomic because changeovers eat the capacity.

How to do it, step by step

Video one full changeover and break it into steps.
Classify each step: internal (machine stopped) or external (can be done running).
Convert every possible internal step to external.
Streamline what remains: fixtures, one-turn methods, parallel work.
Repeat the analysis monthly until changeover stops being the excuse.

Worked example: Cutting die changes on a stamping press

Illustrative scenario — figures are realistic but not from a real company.

An appliance component supplier ran a 400-ton stamping press making brackets and panels in lots of about three days' demand because die changes took around 110 minutes. Finished stock of stamped parts filled half the warehouse, and customer mix changes caused frequent expediting.

The team filmed one die change and listed 46 steps. About 50 minutes were spent retrieving the next die, finding clamps and bolts, and waiting for a forklift, all while the press stood idle.
They reclassified these steps as external, created a changeover cart with all tools and fasteners, and staged the next die beside the press before the current run ended.
For remaining internal work, they standardized die heights with shims so the shut height did not need adjusting, and replaced bolted clamps with quick hydraulic clamps.
Two people now worked in parallel on each side of the press, following a written sequence, while the press was locked out as required by site procedure.

Result. Die change time fell to about 24 minutes after the first round. The plant reduced lot sizes to about one day's demand, freeing a significant share of warehouse space and cutting expediting. The team scheduled a second round targeting under ten minutes, focusing on die alignment and first-piece approval.

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Common pitfalls and how to avoid them

Buying quick-change hardware before analyzing the changeover.Film and classify the steps first; the largest gains often come from preparation and organization at little cost.
Converting steps to external work without assigning who does them.Define who prepares tools, parts and dies during the run, and include this in the standard work.
Keeping the old lot sizes after changeovers shrink.Reduce lot sizes and increase changeover frequency so the time saved becomes flexibility, not just extra run time.
Shortcutting safety steps to save minutes.Keep lockout/tagout and guarding steps intact, and redesign the work around them instead.

Frequently asked questions

What does SMED stand for?

SMED stands for Single-Minute Exchange of Die. Single-minute means a changeover time expressed in a single digit of minutes, that is, under ten minutes. The method was developed for press dies but applies to any changeover, from molding and machining to filling lines and packaging machines, and to setup work in general.

What is the difference between internal and external setup?

Internal setup consists of tasks that can only be done when the machine is stopped, such as removing and mounting a die. External setup consists of tasks that can be done while the machine is still running the previous job, such as fetching tools, preheating molds or checking the next material. SMED shifts as many tasks as possible from internal to external.

How much can SMED reduce changeover time?

Results vary by process and starting point. Changeovers that have never been analyzed often contain a large share of searching, waiting and adjusting that can be removed quickly with preparation and organization. Further reductions usually require engineering changes to fixtures, clamps and alignment. Repeating the analysis in rounds typically brings steady gains.