Editor's note: This blog was originally published in February 2021 and updated with new information in October 2023. 

An abbreviation for Single Minute Exchange of Dies, SMED is the process of reducing changeover or setup time. It involves identifying and eliminating any unnecessary part of the changeover process. When a piece of manufacturing equipment needs to be replaced, the changeover time can lead to costly, unexpected downtime. SMED is an essential part of lean manufacturing that can lower waste, boost productivity, and reduce costs within a process.

The basics of SMED

The SMED system is a principle of lean manufacturing which is the process of doing more with less while delivering maximum value to the customer. Its purpose is to reduce the time it takes to complete changeovers in equipment machinery. This encourages plant employees to perform as many steps as possible before the changeover occurs, have teams working in parallel, and create a standard and optimized process of working. The goal is to reduce any changeover from hours to under 10 minutes, hence the Single Minute Exchange of Dies. Dies refers to specialized manufacturing tools, which need to be re-setup for any changes in production models, resulting in downtime. Japanese industrial engineer, Shigeo Shingo pioneered the SMED system and was able to reduce the changeover times in the companies he worked with by an average of 94%. It is not always possible to reduce your machinery replacement time to under 10 minutes but can be done in most cases.

The benefits of SMED

Smaller lot sizes

Quick, efficient changeovers enable seamless product changes, allowing manufacturers to shift from one lot to the next with ease. Smaller lot sizes can bring about lower inventory costs, reduced waste, and less space requirements for holding and handling materials.

Lower manufacturing costs

By reducing changeover time and planned maintenance with augmented reality and the IIoT, manufacturers can minimize direct materials costs and reduce scrap by up to 50%.

Standardized changeover procedures

When changeovers are quicker, manufacturing floors can reduce equipment downtime and optimize their procedures. One of the main goals of a SMED system is to perform many changeover steps while the machine is running, leaving as few as possible for the actual changeover – slashing unnecessary equipment downtime.

Increased machine work rates

Implementing SMED can help changeover stops take place while machines are still running and streamline material workflows after change-up for faster start-up times.

Better responsiveness to customer demand

Smaller lot sizes, less frequent planned maintenance, and streamlined workflows allow for a more flexible schedule. These benefits can also pave the way for more constructive production planning, which ensures that manufacturing teams are staying aligned with customer needs.

Considerations for SMED implementation

Before implementing a SMED process, you must evaluate which aspects of your current processes are the least efficient. Using industrial internet of things (IIoT) technology, manufacturers can access real-time visibility into all assets to determine which areas of the plant are not operating at maximum asset efficiency. Before a target area is selected to apply the SMED principle, the following elements of production must be taken into consideration:

• There is a high duration of changeover time
• There is variation in the changeover time
• There are regular changeover times, so performance can be measured
• Employees must be familiar with the equipment
• The equipment is a bottleneck for other processes

Once these areas have been analyzed, you can move into the 4 steps of SMED implementation to begin reducing changeover times. 

1. Identify pilot area

A critical part of identifying your test pilot area is ensuring your employees are confident and motivated to improve performance. Fortunately, more complicated elements of the manual changeover can be made simpler using augmented reality technology. Employees can follow step-by-step guided digital work instructions using 3D, spatially aware visualizations that are overlaid onto their work environments. Access to simple, in-context work instructions increases information retention among front-line workers. This dramatically improves their understanding of each step of the changeover process and reduces errors resulting in scrap or rework.

2. Identify internal and external components

Once you have identified your test area, you must understand the internal and external components of the changeover. You must have both an understanding of the work that is going on, and knowledge of the amount of time it took. The SMED system is made up of two main elements during the changeover process:

• Internal elements: These are the processes that must be completed while the equipment is stopped.
• External elements: These are the processes that can be completed while the machinery is running. One of the focuses of external components requires having the appropriate tools and supplies at-the-ready for a changeover.

3. Convert as many internal components to external

The SMED process focuses on making as many elements external as possible. Each component should be analyzed to see if changeover can be worked on while the machine is still running. The IIoT captures enterprise-wide data into assets, processes, and procedures to inform the conversion from internal to external components, which will reduce overall changeover.

4. Streamline internal elements

Once you have identified your external elements, you must streamline your remaining internal elements. A smart connected factory powered by IIoT solutions can make this process seamless—streamlining operations to increase productivity and reduce inefficiencies.

The future of lean manufacturing

The goal of digital lean manufacturing revolves around eliminating waste. By implementing SMED, manufacturers are taking the steps to streamline material workflows after change-up for even faster start-up times. A smart, connected manufacturing line provides manufacturers with even more data on the operation and efficiencies of their parts. This makes it easier to identify which parts reach optimal performance, carry out faster routine maintenance, and improve SMED with digital manufacturing solutions.