Technology • January 26, 2026
When it comes to manufacturing, one of the biggest productivity killers is downtime. And one of the best ways to beat it is with Single-Minute Exchange of Dies (SMED) — a clever concept that’s part of the Toyota Production System.
The history of SMED started in the late 1950s on the factory floor. Shigeo Shingo, a Japanese industrial engineer, noticed that workers spent hours swapping out massive dies weighing tons. The conventional wisdom at the time was that producing big batches was the way to go, because changing over the dies was just too time-consuming. But Shingo saw a problem — workers were spending time searching for tools during downtime when they could have been prepared in advance.
The roots of SMED’s DNA come from the press lines where it was born. Shingo observed a paradox: one die was being installed while another was being prepared, which meant that some of the changeover steps were being done at the wrong time. But he also saw opportunities for simple improvements like tightening bolts in batches rather than one at a time. By the late 1960s, Shingo had perfected the method at a Mazda plant and cut the changeover time on a massive 1,000-ton press from 4 hours to a mere 3 minutes. This proved that SMED wasn’t just for stamping — it could be applied to all sorts of industries.
SMED is a Lean manufacturing technique that aims to cut down the time it takes to switch between production batches. It’s called Single-Minute Exchange of Dies, which literally means changing dies in one minute. But while that’s a great goal, the real aim is to make production more flexible and efficient. And to do that, you separate internal changeover ops (when the machine is stopped) from external ones (when it’s running), and you simplify the internal processes to make them faster.
So what’s the acronym SMED all about? It’s Single-Minute Exchange of Dies — the bit about one minute is just the name, though. What SMED is actually all about is getting changeover times down to single-digit minutes.
Well, here are just a few of the good things that Minute exchange of dies can bring to your manufacturing setup:
SMED in manufacturing gives you:
The SMED methodology is based on the idea of splitting setup work into internal and external operations. This simple separation helps reduce machine downtime in a big way.
Internal operations are tasks that cannot be done while the machine is running:
External operations are tasks that can be done before the machine stops or after it starts again:
The “magic” of SMED is that 30–50% of setup tasks are often done as internal by mistake. Simply reorganizing the work — without big technical changes — can reduce downtime by half.
What exactly is SMED in lean? To put it bluntly, its one of the fundamental tools of Lean Manufacturing and it’s primarily about kicking time wasting habits (like waiting around and churning out extra stuff people don’t need yet) to the curb. The lean SMED philosophy is built on the idea that every second of downtime for your equipment is a chance to make some real value for your customers.
In the lean manufacturing world, SMED works hand in hand with a bunch of other practices:
The SMED definition in Lean is essentially about turning production into a more flexible system that can crank out a variety of products in smaller batches without breaking the bank.
SMED doesn’t operate in a vacuum. You get the most out of it by combining it with other practices.
Changeovers and equipment maintenance aren’t all that different really. Autonomous Maintenance, one of the cornerstones of TPM, teaches operators to do some basic maintenance on their own. The same skills that help with that also come in handy with SMED: an operator who actually knows how a machine works is going to do the changeovers way faster, and a lot more accurately.
Preventive maintenance helps cut down on the risk of breakdowns during changeovers too. Worn out parts, loose clamps, clogged up filters — all these things just increase the amount of time you spend setting up, and increase the risk of cranking out defective parts on the first run.
You can’t even think about doing SMED without a solid 5S setup in place. Changeover tools need to be:
You can’t really make a pull-based Kanban system work if your batch sizes are too big, and small batch sizes are only going to happen if you’ve got really fast changeovers. That’s where SMED comes in: by reducing the time it takes to set up and do changeovers you can bring down the economic order quantity, making Kanban a lot more practical and efficient for managing your production.
For Kanban to really work as intended, changeovers need to be timed perfectly, and that timing needs to be triggered by the visual signal on the Kanban card:
Without SMED, Kanban can’t really unlock its full potential: if you’re stuck with slow setups you end up with bigger batch sizes, which totally breaks the pull-based logic and reduces your responsiveness.
The SMED process is a systematic approach to cutting your setup times down to size. It’s a step-by-step roadmap with four stages that build on each other, gradually making your setup times more efficient.
Stage 1: Get a Grip on Your Current Setup
Before you can make any changes, you need to get a good idea of how things are currently going. That means doing a thorough video analysis of the whole changeover process, from the last good part of the previous batch right through to the first good part of the new one — a concept known as first good piece time.
Data Collection. Don’t skip this bit — capture the whole changeover process from multiple angles using video. Take note of every single step and spend a bit of time with a stopwatch measuring out each operation down to the second. While you’re at it, record all the tools and materials being used, and grab a few minutes of your operators time to chat about the things that are causing them the most problems.
What you’re after is a real-life picture, not some idealised version of what you think things should be like. And yes, you’ll probably find that the official changeover times are way off the actual time it takes — we’re talking 2-3 times longer in some cases.
Stage 2: Distinguishing the Ins and Outs
With your data in hand, it’s now time to apply the SMED formula — classifying each operation as either internal or external. Put together a list where each step is given a label, and use this set of criteria to make your decisions:
With a bit of luck, you’ll find that about half of your operations are ideal candidates for being moved outside of idle time but again, it’s just a matter of spotting what’s possible.
Stage 3: Getting the Best out of External Operations
In our opinion, this is the most exciting stage — now it’s time to make some real changes and get the most out of your external operations.
Conversion Techniques. With so many options to choose from, we thought we’d highlight some of the most productive plus a few honorable mentions.
Stage 4: Getting Every Last Bit of Efficiency
In the final stage, you’re on the lookout for anything and everything that can be improved including operations that can’t be made external.
Optimization Techniques
Car manufacturers use SMED to drastically cut down on the time it takes to switch between different models on a production line. The fact that they can now do in just minutes what used to take hours is all thanks to standardized tools and modular components. Its not dissimilar to the way a NASCAR pit crew work — co-ordinating multiple tasks at the same time means downtime goes down and productivity goes up.
In the food manufacturing industry SMED can mean the difference between a quick change from one product line to another, and a disaster. By getting internal and external components pre-organized you can go from making one snack flavor to another in next to no time. Getting internal components ready in advance makes the whole job that much easier, reduces waste and gets your stuff on the shelves faster — just what consumers want.
Electronics manufacturers use SMED to speed up the process of switching between different circuit board designs. They do this by prepreparing their tools and materials, and identifying all the bits that can be got ready while the machine is still running. This means they can be a lot more flexible when it comes to production schedules. One of the tools they use to speed things up is functional clamps — these make it a lot faster and easier to make those all important tool changes.
Even when you think you’ve got the theory spot on, companies seem to be able to make all the wrong moves and slow down the implementation or reduce its impact.
The urge to go from 4 hours to 10 minutes straight away just ends in disappointment. Sometimes the realistic approach is to take things a bit at a time and build each bit on what you have already done.
Wasting a load of cash on fancy quick-release clamps without training the operators or standardizing procedures is a great way to ensure changeovers continue to be a problem.
Saying “we’ve sped up changeovers” without actually producing any numbers is a load of old codswallop. Without some hard data you aren’t going to be able to manage and actually prove the impact of what you are doing.
Focusing all your efforts on the bits that happen while the machine is stopped is a recipe for disaster. Doing the wrong stuff in one area can actually offset all the good work you are doing in another.
It’s all to easy to treat SMED as a one-off job which you can then tick off and move on to something else. The problem is, that SMED needs to be a constant thing if you don’t keep on top of it the changeovers will just start to creep back up again.
Once you have the basic SMED principles in place, advanced strategies can take it to the next level. Advanced SMED strategies are specifically designed to optimize equipment changeovers and focus on reducing equipment changeover times even further. SMED implementation is a strategic approach within Lean manufacturing aimed at minimizing changeover times to improve operational efficiency. These include:
Yes indeed, SMED principles can be applied to any process with a setup process or transition time. And we’re not just talking about manufacturing here. Any changeover or transition situation where you’re moving from one task to another is a potential candidate for a SMED system. For example, hospitals have used SMED to reduce operating room turnovers between surgeries & prep external setup operations ahead of time, standardize layouts, and bring in extra cleaning teams on the shop floor to keep things moving smoothly. Motorsports are also onto this, using SMED in pit stops, just think about a Formula 1 team whipping off those tire changes in under 3 seconds through sheer standardization, internal setup, and parallel operations. Software deployment uses SMED thinking by automating build processes externally, using blue-green deployments to keep machines up and running and feature flags to decouple deployment from activation. This kind of thing is a big part of a company’s continuous improvement and SMED system journey. So how do you get started? First off, find your pilot area & identify which preparatory activities can happen before the critical transition moment — similar to getting that next batch ready in manufacturing. That way, you can start to see how much more flexible your production becomes across all the different sites, improving overall equipment effectiveness in the process.
It’s not just about that one metric you know — you need to track a whole bunch of other things too. Time variability should decrease — meaning your process is becoming more stable, the number of defective parts you’re producing after a changeover should go down too (because you’re putting a more structured approach in place), and you should be seeing more changeovers per month (because you’re moving to smaller batches and better production leveling). Also, Work in Progress in units or days of inventory should be going down, and response time to customer orders should be getting faster. And then there are the intangible metrics you need to keep an eye on: are your operators happy and less stressed? Are they coming up with more improvement suggestions from the team especially across different shop floor teams? That all says a lot about engagement and production flexibility.
Well that’s pretty common, you’ve probably picked up all the low-hanging fruit, but there’s still plenty of room for improvement. Time to take a closer look at the process, maybe even re-shoot that video and break it down to frame-by-frame detail. Then apply the “5 Whys” method to the remaining bottlenecks, every time you ask “why is it taking so long”, you’re going to uncover something new. Sometimes a fresh perspective is what you need — get someone in from outside, or an employee from another area or shop floor who can come in and ask some “silly” questions. And don’t be afraid to look elsewhere for inspiration maybe your solution is hiding in plain sight in another industry. And lastly, investing in some more advanced technical solutions — like automated tool changers or robotics — can really help take your SMED system to the next level and support production flexibility even more.
Absolutely — that’s where the benefits of SMED are most visible. In small batch production changeovers are happening all the time, sometimes even multiple times a shift. But here’s the thing — even when each order is unique the changeover process itself is still standardized: the sequence of actions, tooling used and clamping methods are all the same, regardless of the part. So create a modular tooling system with quick-change elements — keep the base plate in place & just swap out the inserts to fit the specific part geometry. Use universal tooling with adjustments via stops and templates instead of making a new fixture every time. And standardize the process, not the product — that’s the key to higher production flexibility, smoother transitions between batches and better production leveling across the whole shop floor.
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