Single Minute Exchange of Dies – The Complete Guide

single minute exchange of dies-pit-stop

Single Minute Exchange of Dies is a mouthful, i agree. But It’s an important tool in the lean production framework, and can benefit many businesses. Here, I’ll explain what it is, the benefits and how to use it.

What is Single Minute Exchange of Dies? It’s often referred to as SMED or Set up Reduction, and is a process where you can drastically reduce the set up time of a machine or key process. It consists of observing a typical changeover, identifying all the tasks that go into this changeover, and then eliminating as many as possible, by converting them to tasks that are done whilst the machine is running. The result being faster turnaround times and higher up-times of machines, which result in increased capacity and productivity.

As it’s a critical lean tool, there’s a little more to SMED to make it work for you. This guide will show you exactly how to do it.


Table of Contents

Why Single Minute Exchange of Dies?

We’ll look at what’s all the fuss and why it can transform your business from the ground up.

What is a Set-up or Changeover?

Let’s discuss exactly what a set-up is, so we can then analyse and improve it. You’ll get some examples to help, too.

The Benefits of SMED

There are many benefits of single minute exchange of dies. We’ll discuss what you can expect by implementing it effectively.

The 8 Steps to SMED

You’ll learn the 7 steps to improving the set-up times of your machines, so you can reap the rewards.


Single Minute Exchange of Dies -Why Do it at All?

Imagine this scenario:

You’re in charge of a large manufacturing company. Your data analyst has crunched some interesting numbers and shares them with you over coffee:

  • Total direct labour hours available last year has been 692,000 hours
  • The the total hours lost to setting up machines, and which are reported on the system are 40,609 hours
  • The average machining cost per hour is $50
  • The total cost of setting up machines per year is a little over $2 million!

This was something you never really thought about addressing. After all, set-ups have to happen and are a part of production, right?

Your analyst prompts you, “what if we can reduce set-up times by a third? We’d manage to save over $600,000, plus back-fill this extra time with more sales.”

Now, that’s a good basis to start looking into reducing set-ups. That’s where single minute exchange of dies comes in…

If you can turn your machines around faster, you can reduce the cost to the business and increase sales capability.

The concept of SMED came from Toyota who pioneered the approach. To them, every set-up should be less than ten minutes… hence the “single minute” terminology in the title.

Toyota knew that fast turnovers means increased competitiveness and capability in giving their customer what they want, when they want.

What is a Set-up or Changeover?

A set-up is simply the time elapsed from the last good unit of production of the previous job, to the first good unit of production for the next job.

This time in between involves the changeover process and can typically include the following steps:

  • Material changes
  • Purges
  • Changing of tools and dies
  • Changing size and dimensions
  • Changing fixtures and jigs
  • Reprogramming equipment
  • Process setting and resetting
  • Cleaning and wiping down
  • Getting information or additional tools

A set-up essentially involves any change needed to allow the machine to switch from the previous run to being able to run the next job at the correct specification.

You’ll find that when you analyse a changeover, there’s also a lot of walking, searching, and time lost through movement. This also adds to the overall set up time.

A Mindset Shift

Traditionally, people see set-ups as a problem. Their mindset is that if only they could keep the machines running, then everything would be fine.

To counter this, people with this mindset, often explain that what’s needed is to increase the batch sizes, and maximise run time. By doing this, changeovers happen less frequently, and you’ll optimise productivity.

I’m afraid, this thinking is flawed.

And it’s flawed in a number of ways.

You’ll be over producing products, which is a waste. Not all the work is needed now, as you’ve actively increased batch sizes. This means that you’re spending a lot of time on producing work that’s not needed right now, whilst putting back other jobs that are needed.

Also, the more inventory you have around you, the harder it is to control costs, space, quality, and meet customer lead time.

The bigger the runs, the more space you need to hold this excessive stock and the more time products are waiting in the queue for their turn on the lines.

The bottom line: The bigger your batches, the more you slow down your production system. We’ll get to this in a little detail, shortly.

The New Age Warrior!

Innovation requires different thinking, different angles and the ability to challenge the current mindsets.

Toyota realised this, and found that set-ups are not the problem at all.

It’s simply the time they take that’s the problem.

In fact, more changeovers are good! The secret to lean is reducing batch sizes.

The smaller the batches, the more agile your production system is.

This then means that you have to process many more set-ups and changeovers. But by doing this, you can cycle through much more work, faster, and only make to customer demand.

faster-setup-versus-slower-setup

If you can reduce your setups to minuscule amounts of time, then changeovers and set-ups are not a problem at all. (As in our example above)

In other words, if you can reduce your set-ups you can become faster, leaner and more agile, meeting customer demand more efficiently.

How Would You Change 4 Tyres?

How long would it take you to change four tyres on you car?

I reckon around 15 to 20 minutes.

If you had a chance to analyse all the work content that goes into this activity, you’ll find that there are many things to do. Some of which are:

  • Going to get the jack
  • Get the wheel
  • probably even have a look at the car manual
  • Jack the car
  • Unscrew all the bolts
  • Reach over and get the new tyre
  • Replace
  • Tighten the bolts
  • Give them one last check
  • Put the old tyre away

The Formula 1 Alternative

If you stripped it all down, the only activity that has to be done when the car is stopped is to remove and replace the tyres.

All the other things could be done in preparation to the car coming to a stop. They can be external to this changeover process.

Doing things this way can create a huge impact in the time the car is stopped and indeed turned around.

In formula 1, the record is around 2 seconds. That’s 2 seconds for the car to stop, to change all four tyres and then to set off again. Here’s the Youtube video from Scott Belchambers.

F1 Single Minute Exchange of Dies in Practice

See how the pit-stop process has been practised to perfection. Notice too, the other activities carried out external to the actual tyre change operation.

So, why can’t you follow the same principles with your machines?

The truth is you can.

It takes a clear process to do it (I’ll show you this later in the article), and practice.

The Benefits of Faster Changeovers

It’s pretty obvious what the benefits are to getting this right… To seeing your machines that once turned a set-up round in 2 hours and can now do it in 10 minutes.

Here’s what you should expect if you challenge absolutely everything in your set-ups, and reduce them.

Reduced Batch sizes –It’s a fact that the bigger your batches are, the longer jobs take to run.

This then means that more work is queued, waiting for their own slots in the process. And if all your batches are large, then sooner or later you’ll experience a vast bottleneck, where things appear stuck.

Daily prioritisation meetings often take place, to help important jobs jump the queue. Sooner enough, all things are a priority.

People are busy and working hard, but everything seems stuck in the system. Nothing seems to get produced on time.

The fact is: the larger the batches, the slower your manufacturing processes.

On the contrary, the smaller the batches, the faster your processes become. Quick changeovers allow you to reduce batch size so you can speed up your turnaround times.

Improved Flexibility – By the same token, a faster turnaround time, and the ability to process more jobs, means that you’ll be able to offer more flexible delivery to your customers.

Your customer wants 50 units but your minimum order quantity is 5000 in order to be productive?

Improving your changeovers allows you to reduce the minimum order quantity. Get to 50 units and you have a competitive advantage that most of your competitors won’t be able to follow.

By implementing quicker changeovers, you’ll be able to make only what the customer wants and considerably quickly… Therefore reducing lead times.

Increased Return on Investment – By increasing the uptime of your machines and getting more out of them, you’ll be able to process more sales.

More sales means a greater return.

By increasing changeovers, and reducing your downtime, your uptime is increased and so too output, sales and profitability.

Reduced inventory levels is also a result of fast set-ups and the ability to changeover quickly. If your minimum order quantities are low, then you’ll hold less inventory.

You’ll also be able to increase capacity. What was once written off as dead time and the time it took to changeover… a vast proportion of this time can now be allocated to additional process time for producing what your customers want.

In addition to being in this great position, you may well be able to hold off buying that new machine to allow you to process more output. This by default, means that you’ll spend less capital expenditure on new equipment.

The more you reduce the set-up times of your equipment, the more these benefits will impact your business.

The 8 Step Approach to Single Minute Exchange of Dies

There is a simple process to follow, which will allow you to optimise the changeover times on your machines.

This 8-step process will show you how to implement single minute exchange of dies philosophy into your business, so you can expect drastic savings in set-up time.

You’ll also see that in the diagram below, as you progress through each stage, your improvements in time and affect on the changeover, increases.

Single minute exchange of dies process and improvement over time

Step 1: Observe The Current Set-up

The vital ingredient to lean and process improvement is to observe.

This step is no different.

It’s simply done by recording each step in the process:

  • By sequence
  • And the time taken

How Do You Do It?

Watch a typical set up – this is normally done by videoing the entire process from the last good unit of production of the previous job, to the first good unit of the next.

Take a camera, and ensure you video the following typical steps:

  • Preparation: After-process adjustments, checking equipment and tools, cleaning up
  • Mounting and removing: removing tools and replacing equipment and parts for the next run
  • Measurements: Conducting measurements and adjustments, as well as calibrating
  • Trial runs and adjustments: Run first-off runs and then conducting adjustments until satisfied and the first good part is acheived

If done correctly, you should have a detailed and often lengthy video of the entire process.

Take a note pad with you, and whilst you’re filming, take notes of any improvement ideas you may have as you go.

Step 2: Review & Map the Process

With a team (including the operators), observe the video and start the process analysis.

The objective here, is to transfer the process from the video, onto paper… in exactly the way it happened.

The standard model is to use a work element table, like the following:

Work-Element-Template

Simply, pause the video as you agree each element of work and add it to the chart. It’s best to capture on a flip chart, so draw the template above on a flip chart paper.

For each element, whether each activity is currently either:

  • An internal activity: One that is conducted whilst the machine is stopped
  • An external activity: One that is conducted whilst the machine is running

As you go, identify the time it takes to complete each task.

In tandem, on another flip chart, record any ideas you have to improve the set-up, as you go, as well as the ideas you’ve already documented during the videoing stage.

A Personal Preference – MAP IT!

I like to transfer the steps from the work element sheet to a simple process map.

This is optional, but for me, being somewhat of a visual person, it’s easier to see the whole process when it’s up on a wall and displayed as post-its.

If you’re the same, then try this.

Once you have your set-up process observed and noted on your work element table, transfer each step onto a post-it and stick it to the wall.

Add the time it takes, along with the task on each one.

Example process map for a setup process

Once you have this process map up, it’s easy to move steps around, so you can show work in parallel or convert some activities to external, as well as adding notes and improvement ideas as you go. (We’ll discussed these activities next)

Step 3: Convert as Many Internal Activities to External

Once you’ve gone through the analysis and documented the internal and external activities, it’s time to hone in on making improvements to the current way things are done.

By now, you’ll already have a number of good ideas and ways to improve the set-up.

We don’t want to stop there, though. We want to optimise the complete set up process.

This means looking at the internal activities that we have on our current state and identifying creative ways to turn them into external activities.

Internal-to-External-Activities

At this stage, we are a bit more stringent on our definition of what an external and internal activity is:

  • An Internal Activity is anything that MUST be conducted whilst the machine is running
  • An External Activity is anything that COULD be conducted whilst the machine is running

The following are prime candidates for converting internals to externals:

  • Tooling proving / preparation
  • Pre-heating of dies and plates
  • Pre-loading of information
  • Pre-setting of tools and equipment
  • Using jigs
  • Using setting aids
  • Getting materials and equipment

The general idea of quick changeover is to prepare for the operating conditions in advance, so you can turn the machine around faster when it has to be stopped…

As you move along your map, try to convert as many internals to externals.

Think about novel ideas and techniques to be able to do this.

Here’s a comparison between the traditional set-up approach to the SMED alternative.

Internal-and-External-Activities-in-SMED

Remember, just because the process is done this way today, it doesn’t mean it has to be like it tomorrow. Challenge all activities to try to reduce as much internal time as possible.

Step 4: Create Parallel Tasks

Parallel activities are normally conducted independently of each other. In the current state set-up process, they’re separate activities which are not related. For example:

  • Go and get the jig for the next job
  • Measure the machine’s position
  • Go get the material and test prior to production

In a nutshell, parallel activities are independent of each other and CAN be performed simultaneously.

In our bullet points above, why can’t all 3 activities be performed at the same time, by a number of people, whilst the machine is still running the previous job?

The answer is that they can be done. And they should be done to improve set-up times.

50% Reduction Through Parallel Tasks

When you start creating many parallel activities together, you normally find that a 50% reduction in time is perfectly achievable.

So, if you’re changeover time is 2 hours, just be applying parallel tasks, you could expect around an hour saved.

The big paradigm shift here, is to apply a team ethic.

Stop thinking about one-person one-machine. Instead, think of it as a team that keep the machines running to demand.

Successfully conducting many parallel activities can only be done by this teamwork approach. The best way to think about it is the Formula 1 pit-stop or the Nascar equivalent.

The team run around preparing for the changeover event. In this case, this event is the tyres changed.

If they were to treat the activity as one mechanic and one car, then they’d never stand a chance of winning the race. Better still, here’s another way of thinking about changeover activities…

1 person conducting 20 Minutes of Work = 20 Minutes

Yet…

6 people conducting 1 minute of optimised work content, in tandem = less than 10 minutes

Step 5: Optimise Remaining Internal Activities

There would be some considerable improvements made so far.

  • Many current internals have now been converted to external tasks
  • A number of parallel tasks have been defined to speed up even more time

Now it’s time to fine tune the processes that have to be conducted whilst the machine is down.

For this phase, it’s best to transfer these internal tasks to another template:

It’s time to take each internal activity and challenge how it’s done.

Do this by:

  1. Define the step
  2. Agree why it happens
  3. Challenge how it can be improved – Think of quick release mechanisms, faster tooling, and challenge legacy processes
  4. Agree an action(s) to reduce the time it takes
  5. Capture the estimated new time it would take to complete the task and add it to your new map.

Here are some hints to help whet your creative juices:

At the end of this process, you should have a new set-up process that is much faster than the previous, and with the essential internal activity tasks vastly reduced in time.

Step 6: Develop the New Set-Up Standard Work

Now’s the time to develop the new and agreed way of changing over your machine.

We need to make all our hard work pay off… and make it the norm.

That’s why we standardise these steps.

And when it comes to standardising, we want to ensure that:

  • All external tasks are done at the right time
  • All the parallel tasks are completed at the same time and with the right number of people
  • All internal tasks are followed based on the improvements we’ve identified
  • We define the new total setup time

We’ll need a standard document here. This SOP (standard operating procedure) will define the following:

  • Which operator does what activity and when it should be done
  • An image of each activity
  • the time it takes to do each task
  • The target time for the entire set-up process

It’s a first draft, so can be changed and improved. But nevertheless, it’s the new standard.

Step 7: Trial the New Procedure

With the new procedure documented, it’s time to trial and iron out a few things.

It’s also a time to identify potential concerns or issues you may not have heard.

Communicate this new procedure to the teams and train them to ensure they have full buy-in and understanding when it comes to the next changeover.

Trial the method in real time and document any issues. Be prepared to change and amend the process where you need to and based on what you observe.

Step 8: Validate the Results and Lock in the New Standard

Once you’ve taken actions and further improved the set-up, it’s time to quantify the savings and roll out the finalised standard work document.

Here’s what you need to do:

  • I’d also advise to discuss and verify these time savings with the accounts team, so they can quantify and confirm the improvements.
  • Add this to a continuous improvement log – where you can track the savings and improvements made over the year.

Believe it or not, by adding each quantified improvement as you go, you’ll be pleasantly surprised with the outcome at the end of the year!

  • Track the changeover times. From now, on chart the changeover performance, so you can monitor the actual time to the target (the standard work targeted time).
  • Use this to constantly challenge the changeover times, so you can continuously improve

And don’t forget to repeat this process with all other machines, so you can drastically improve uptime and flexibility across the business.

Here’s what you can typically expect with each round of the Single Minute Exchange of Dies Set-up reduction process:

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