Short for Single-Minute Exchange of Die, SMED is a method of lean manufacturing used for a quick, simplified, and efficient production set-up and changeover from one product or process to another, with the aim of reducing non-productive downtime and stoppages.
Setup times are costly, and manufacturers may be tempted to overproduce to amortise this cost over more parts, however, this can lead to increased stock levels, higher levels of working capital and the lack of flexibility to respond to changes in customer needs. So, how can SMED reduce inefficiencies in manufacturing?
SMED reduces inefficiencies in manufacturing in several key ways, including lowering manufacturing costs, reducing setup and changeover times and improving customer demand responsiveness, among other things.
This article looks at how the lean manufacturing method of SMED can be used to help manufacturers reduce inefficiencies in their manufacturing processes and support their continuous improvement strategy.
Before we go any further, we need to look at exactly what SMED is.
Like many strategies that focus on process improvement, SMED began in Japan in the 1950s when a Toyota consultant noticed an inefficient process involving the body moulding process. Much of the waste came from the time it took to switch to new tools used on the equipment that was needed for the different phases of the body moulding process.
The changeover took between two and eight hours with Toyota also having to spend money storing vehicles being built. It was projected that Toyota could save money by speeding up the changeover process.
The improvements needed all focused on less changeover time. This meant modifying the factory equipment, and the vehicle parts and changing the order of the steps in building the car body mouldings. By the 1970s, the changeover was just three minutes.
A SMED exercise focuses on making the Changeover period as efficient as possible, ultimately leading to a changeover that takes less time.
Understandably, other industries wanted to emulate this success. SMED principles are now applied to any changeover process, from building software to competing in motorsport such as the F1 example mentioned earlier.
Formula 1 pit-stops are often used as an example of a SMED process. Many of the processes for the setup and changeover of tyres are SMED due to the prepositioning of the equipment that will be used, and the quick attach/release nature of the tools used. For many people, changing a car tyre can take 15 minutes, for an F1 pit crew it takes less than five seconds.
In this article, we’ll be looking at how SMED principles can benefit manufacturers to remove inefficiencies.
SMED allows manufacturers to minimise machine downtime which occurs between part-to-part set-up on a machine and the steps tend to take place in one of two areas: external and internal setup components.
Internal steps occur when the equipment/process is stopped whereas external steps occur while the equipment/process is progressing. Both are important elements of SMED manufacturing which has the aim of achieving a changeover time in under ten minutes, in other words, ‘single-digit minute’ hence, the ‘single minute’ part of the name. SMED focuses on making as many of the changeover elements as possible as external steps while simplifying and streamlining all elements.
By getting a machine up and running quickly, it is possible to ensure you are only manufacturing the product you need to fulfil orders while maintaining high levels of productivity.
A successful SMED program can have a number of benefits, including:
Lowering manufacturing costs as faster changeovers mean less equipment downtime, therefore increasing the available capacity of the process. These faster changeovers enable more frequent product changes and improved customer demand responsiveness as smaller production runs allow for more flexible scheduling.
In conjunction with other lean principles such as Poka Yoke, it is possible to improve the quality of the setup and reduce errors, meaning a higher rate of conforming product may be produced from the process.
Training new operators on processes becomes quicker as they have less to learn, especially if different setups can be standardised or rationalised.
Before implementing a SMED initiative within your manufacturing processes, it is important to have a clear understanding of where production time is being lost and any decisions on improving processes are made using accurate and up-to-date data. This means having a process and system in place to collect and analyse performance data from production machinery.
Machine monitoring enables you to collect real-time data that allows you to identify opportunities for improvement. It also helps you to accurately monitor the time between a process ending and the machine being set up again.
Once a measuring system is in place, it is important to gather enough data to gain a clear picture of where production time is being lost, and where the biggest opportunities are to reduce set-up times and improve process efficiencies.
Considered to be one of the world’s leading experts on manufacturing improvement practices, Shigeo Shingo, who created the SMED approach, outlined eight techniques that should be considered when implementing SMED.
There are seven steps which should be followed when reducing changeover using the SMED method, these are outlined below.
The image shows the 7 steps of a SMED exercise which we explain further below.
The ideal equipment to run a SMED exercise on should have a changeover time long enough to have significant room for improvement and a large variation in changeover time. Also, there should be multiple opportunities to perform a changeover each week so that any changes can be quickly tested.
It is widely cited, that for each iteration of the above seven-step process, a 40-45% improvement in set-up times should be expected. However, as the old saying goes, practice makes perfect, so you can expect it to take several iterations to achieve the ‘under ten minutes’ SMED goal.
To help create support for the project, it is important to engage employees in the selection process to create a consensus within the team as to the piece of equipment chosen.
Ensuring all operators are engaged also improves the adoption of the new method. Learn more about the seven steps below. Or, why not book a demo to see it in action?
Once selected, you enter the observation phase to record a baseline time for the changeover. This should be measured as the time between the production of the final piece and the production of the first part. Be aware that changeover times may temporarily improve as a simple result of observing the process. Always use the previously captured baseline data to give a baseline changeover time.
The next step is for the team to work to identify the elements of the changeover and separate them into internal and external activities. A great way of doing this is to record the changeover and work from that to create an ordered list of elements. This should include a description of what work is performed and the cost in time and how long the element takes to complete. This should give you a complete list of changeover elements with a description and time cost.
You then need to look at the elements of the changeover process that can be performed with little or no change while the equipment is running. This should give you an updated list of elements that are split into three parts: external elements (before the changeover), internal elements (during the changeover) and external elements (after the changeover). You can then look to convert as many internal elements to external as possible by asking if there was a way to make this external, what would it be and how could we do it? This will give you a list of elements that you can take further action on and can be prioritised so the most promising ones can be acted on first.
Finally, all internal and external elements should be reviewed with an eye towards streamlining them so that they can be completed in less time. Remember to keep an eye on the accurate data that machine monitoring is providing you with so you can hone the process and eliminate as many inefficiencies as possible. The changes that you have made should be documented and then repeated to look for any further changes that can be made to further improve the SMED process and reach that magic under-ten-minute goal.
Some of the changes you make may be simple, such as reducing the number of turns on a thread for a screwed-in component, while others may be more technical, such as a highly accurate quick-release fixturing. However, they all add up to maximising the uptime of the machine or process.
Having reliable, accurate machine data is key in a lean manufacturing environment, and it is especially true when performing lean production methods such as a SMED exercise. Having real-time data allows you to understand your current baseline and where the biggest improvements can be made to your manufacturing processes, leading to speedier, more efficient changeovers, increased productivity and improved Overall Equipment Effectiveness (OEE).
If you’re looking to conduct a SMED or improve any of your manufacturing processes, our advice is to make sure you understand your current production efficiency to give your continuous improvement efforts the best possible chance of success. An affordable and accessible way to do this is by deploying smart technology, such as machine monitoring software across the factory floor.
Manufacturing analytics software such as this will give you:
This data insight will help ensure your SMED has the best possible chance of success as well as give you several tangible benefits across your manufacturing operations, including:
To find out more about how FourJaw can help you achieve your SMED and Lean Manufacturing goals, contact us today.