SMED on the Sewing Floor

SMED, single-minute exchange of die, was born in metal presses, but its core insight moves to sewing floors intact: most of what happens during a changeover could have happened before the line stopped. The hours between the last piece of one style and full pace on the next are not a fixed cost. They are a design.

Internal versus external, the whole trick

Classify every changeover task by one question: does it require the line to be stopped? Threading new machines, adjusting guides on the line's own equipment: internal, the line waits. Preparing folders and attachments, staging trims and bundles, briefing the method, pre-setting spare machines off-line: external, all of it doable while the previous style still runs. The first SMED pass on most sewing changeovers finds half the stopped-time is external work being done internally, purely by habit.

The choreography

A changeover worth the name has a script: who does what, in what order, the moment the last bundle clears. Mechanics converting machines in a planned sequence rather than on demand; quality confirming first-off pieces station by station as they appear, not at the end; the supervisor walking a fixed route. The difference between a scripted and an improvised changeover on the same style pair is routinely a factor of two, with no capital spent.

Measure it like the loss it is

Changeover time belongs in the loss tree as its own named branch, captured when it happens: minutes from last piece to first piece, and separately to steady pace, because the ramp after restart is where the learning curve takes over. Once measured, changeovers can be compared: by style pair, by line, by day of week, and the outliers interrogated. Unmeasured, every changeover took as long as it took, and improvement has nothing to grip.

Beyond sewing

The same lens pays across a composite mill. Beam changes in weaving are changeovers measured in days; batch changes in dyeing carry cleaning cycles that are partly external; cutting table changeovers hide in marker and lay preparation. Wherever the process stops to become ready for different work, the internal-external question applies, and the answer is usually the cheapest capacity you will ever add: hours that were already yours, returned.