SMED (Single Minute Exchange of Die)
SMED is a method for drastically reducing setup times. Goal: Every changeover in under 10 minutes, in the single-digit minute range.
SMED (Single Minute Exchange of Die) was named and described by Shigeo Shingo. He drew on changeover projects that he supported as a consultant at Toyo Kogyo (now Mazda), Mitsubishi Heavy Industries and Toyota. The method distinguishes between internal setup (machine stopped) and external setup (machine running).
The core of SMED: Shift as many setup steps as possible from internal to external. This means: Prepare everything while the machine is still running. Then only perform the unavoidable steps with the machine stopped.
In practice, setup times are often dramatically underestimated because they are accepted as 'necessary.' SMED shows that 50-90% reduction is almost always possible, often through simple organizational measures without any investment.
Shorter setup times enable smaller batch sizes, which in turn reduce lead time, lower inventory levels, and increase flexibility. SMED is therefore a key enabler for one-piece flow and just-in-time production.
Practical Example
A stamping press has a setup time of 90 minutes. After SMED analysis: 35 minutes are external setup (preparing tools, pre-sorting bolts, reading the next order). These are completed before the stop. Another 25 minutes are eliminated by using quick-release clamps instead of screws. New setup time: 30 minutes, a 67% reduction.
How Lean Shift Helps
When you record a changeover step by step, LeanShift times every setup step individually and over several cycles. Whether a step is internal or external depends on whether it can only be done while the machine is not producing. You make that call yourself, and the measured times show you which steps take longest. When you restart the recording after a change, the fully timed cycles of the earlier recording are kept and you compare the old one with the new one. In the value stream, you give setup a tile of its own that takes the recording’s actual time as its changeover time, averaged per step and added up. If the recording also times external steps, they count toward the tile’s changeover time. Subtract the time of these steps by hand in the “Changeover Time (C/O)” field, because changeover time runs from the last good part of the previous product to the first good part of the next.
Frequently Asked Questions
What does SMED actually mean?
Single Minute Exchange of Die, die change in the single-digit minute range. The goal is not necessarily under one minute, but under 10 minutes (single digits).
What is internal and external setup?
Internal setup: Activities that can only be done with the machine stopped (e.g., changing the tool). External setup: Activities that can be prepared while the machine is running (e.g., staging materials).
How long does a SMED implementation take?
An initial SMED workshop typically takes 2-3 days. The first improvements (30-50% setup time reduction) are often immediately achievable. Further optimization follows iteratively.