What is SMED

Guide: SMED (Single Minute Exchange of Die)

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Daniel Croft

Daniel Croft is an experienced continuous improvement manager with a Lean Six Sigma Black Belt and a Bachelor's degree in Business Management. With more than ten years of experience applying his skills across various industries, Daniel specializes in optimizing processes and improving efficiency. His approach combines practical experience with a deep understanding of business fundamentals to drive meaningful change.

In the pursuit of efficiency, Single-Minute Exchange of Dies (SMED) is a transformative methodology. It’s a system designed to drastically cut down the time taken for changeovers. Pioneered to combat the productivity losses during these periods, SMED is integral to enhancing Overall Equipment Effectiveness (OEE). By scrutinizing changeovers into external and internal setups, it seeks to perform as many tasks as possible without halting the machines, streamlining transitions in diverse industries, from automotive to food production.

Table of Contents

What is SMED?

SMED is a methodology that stands for Single-Minute Exchange of Dies and is aimed at reducing the time it takes for changeovers, which is switching from one product to another in a manufacturing process. Often, the process of switching from producing one product to another involves adjusting or changing tooling and equipment. If not planned well can take a significant amount of production time and would be classed as downtime and non-productive time if measured in Overall Equipment Effectiveness (OEE).

Key Elements of SMED:

Within SMED, a changeover is split into two distinct parts: an external setup and an internal setup.

External Setup: External setup tasks are activities that can be done while the current production process is still running. For example, collecting necessary tools or pre-heating a die for a stamping machine Doing these activities does not disrupt the current production process.

Internal Setup: Internal setup tasks are activities that can only be performed when the machine or process has stopped. An example of this would be the insertion of a new die into a press. This activity is not possible to do on an active machine or production line.

The objective of SMED is to transition as many internal setup steps to external steps as possible. This would result in a reduction in process downtime for changeovers. Where it is most beneficial is car and automotive plants, where a changeover can take hours to days to switch from producing one model to another. Or in fish or other food production factories where changeovers for different customers of fish types can be more than 20 times in a day, even a 5-minute changeover can result in 100 minutes of downtime in a day which is significant, and being able to reduce that down to a 2.5-minute changeover would save 50 minutes, or around 10% of a standard shift time.

 

The History and Impact of SMED

Shigeo Shingo developed SMED when he observed that a significant amount of production time was wasted with elongated change-over processes. By analyzing and modifying steps that are involved in changeovers, he was able to reduce setup time from hours to minutes, hence the name “single minute,” indicating the goal of reducing setup times to a single-digit number of minutes.

The implementation of SMED at Toyota resulted in a revolution in the manufacturing process, contributing to the success of the Toyota Production System (TPS), which later evolved into what is known as Lean Manufacturing.

Example of SMED in Action

A classic example of SMED changeovers cvan be seen with F1 pitstops.

SMED Observations in F1 Pitstops

  • Pre-arranged Tools and Parts: Tools and replacement parts are laid out in precise order for easy access.
  • Streamlined Processes: Every task is refined to the fewest possible movements.
  • Concurrent Activities: Team members perform different tasks simultaneously to save time.
  • Precision Timing: Every action is perfectly timed with the others, down to the second.
  • Practiced Movements: Crew members repeatedly practice to ensure smooth execution.
  • Quick-Release Mechanisms: Wheels and components are designed for fast removal and attachment.
  • Pre-Set Equipment: Tires are pre-warmed and ready for immediate use.
  • Error-Proof Design: Equipment is designed to only fit in the correct orientation (poka-yoke).
  • Standardized Roles: Each team member has a specific, unchanging role.
  • Clear Signals: Drivers and crew use clear, predefined signals for communication.
  • Rapid Correction: Mistakes are immediately addressed with practiced contingency plans.
  • Efficiency Analysis: Every pit stop is reviewed for potential improvements.
  • Team Coordination: The pit crew functions as a cohesive unit, with a high degree of discipline and synchronization.

How to Implement SMED

Implementing SMED requires a structured approach to minimize changeover times effectively. Here’s a detailed look at each step:

Step 1: Observe and Document the Current Process

The first step of SMED is to look at the current state of the process changeovers. This can be done with observations of the current process and reviewing existing documentation. This step is important, as you cannot improve what you have not measured.

This is done with initial data collection, which can be done with a stopwatch to capture the time. It is recommended to use a video recording of the process for a more detailed analysis that can be watched multiple times.

Break down the process into individual steps, no matter how small the steps are, and record how long each step takes. At this stage, you should involve the operators who perform the changeovers, as they offer practical insights and details that may not be obvious to an external observer.

Step 2: Separate Internal from External Activities

The next step is to separate the changeover activities into two categories, which are foundational to SMED.

Create two lists, Internal Activities and External Activities, and assess each step critically, asking if the equipment must be stopped to perform the task. Once these lists have been created, ensure to involve the team in reviewing the lists, ensuring nothing has been overlooked or put on the wrong list.

Step 3: Convert Internal to External Setup

Once the tasks are separated, the next focus is to consider how Internal setup activities can be converted into External setup activities. This can be done by looking at the internal activity list and finding tasks that can be prepared ahead of time. For example, in an F1 pit stop, tires can be brought to the pit stop, wheel guns can be checked, etc., before the car gets to the pit box.

Sometimes, converting a step may require creative solutions or modifications to equipment or procedures. Following the changes, procedures should be updated to reflect the changes from internal to external setup activities.

Step 4: Streamline Remaining Steps

The remaining Internal setup activities that cannot be converted to external ones should be streamlined as much as possible. This can be done with methods such as quick-release fasteners in place of bolts so that tools are not needed to remove them or reduce the number of fitting points like in F1 with the single wheel nut instead of 4 of 5.

Aim to remove any unnecessary movements or steps that do not add value to the setup process and ensure that the remaining internal setup tasks are performed in the same way each time to create consistency and muscle memory, allowing operators to perform changeovers in a second-nature manner. 

Step 5: Implement the Changes

Following this, the changes should be implemented as a new changeover process. This will require some pilot runs to test whether the changeover works as expected and make adjustments where necessary. Once you are happy with the changeover process, conduct training to ensure the operators know what to do, how to do it, and when to do it.

Step 6: Continuous Improvement

Finally, it is important to highlight that SMED, like all continuous improvement methods, is not a one-time event, and the process should continue to be monitored for further improvements. The use of mechanisms for operators to provide feedback on an ongoing basis should be implemented.

Tools and Techniques to Support SMED

Implementing SMED effectively often requires a combination of practical tools and techniques that enable quick and efficient changeovers. Here is an in-depth look at each one:

Visual Aids

Purpose: Visual aids are used to communicate the steps of the changeover process quickly and effectively. They can significantly reduce the time taken to recall procedures and confirm correct completion of tasks.

Types:

  • Diagrams: Diagrams can map out the sequence of steps in a changeover, highlighting critical points that require attention.

  • Photos: Before and after photos help to visualize the correct setup and positioning of tools and parts, providing a clear reference.

How to Implement:

  • Location: Position the visual aids at the point of use, ensuring they are easily accessible and visible during the changeover.

  • Design: Incorporate color-coding and clear labels, potentially using your theme color #167a68 for consistency and ease of recognition.

Standard Operating Procedures (SOPs)

Purpose: SOPs provide a standardized set of instructions that anyone can follow to perform changeovers in a consistent and efficient manner.

How to Implement:

  • Detailing: Develop comprehensive SOPs for each changeover step, including both external and internal tasks.

  • Accessibility: Make these SOPs easily accessible, either printed out at the workstation or available digitally through tablets or workstations.

  • Review and Revision: Regularly review and update the SOPs to reflect any improvements or changes in the process.

Shadow Boards

Purpose: Shadow boards are organizational tools that use outlines or “shadows” of tools on a board to indicate where each tool should be placed. They help in maintaining organization and reducing the time spent searching for tools.

How to implement:

  • Design: Create the board layouts with outlines or shadows of the tools in their exact shape and size, using contrasting colours to make identification instant.

  • Placement: Position shadow boards at the point of use to minimize the movement required to retrieve and return tools.

  • Training: Instruct all users on the importance of returning tools to the correct location on the shadow board after use.

Conclusion

SMED is not just a set of steps but a philosophy embedded in the drive for continuous improvement. Its principles, reflected in the careful choreography of F1 pit stops, underscore the value of agility and precision in operational excellence. By documenting and analyzing each action, categorizing tasks, converting setups, and refining processes, SMED transcends traditional production practices. It’s a strategic quest for the elusive yet attainable goal of seamless efficiency. As industries evolve, SMED remains a important for those working in the complex area of manufacturing and process optimization, underscoring that sometimes the most significant advancements lie in the minutiae of seconds saved and motions perfected.

References

A: SMED stands for Single-Minute Exchange of Die. It is a methodology focused on reducing the time required to change over equipment or tooling. The goal of SMED is to minimize setup time, increase operational efficiency, and enable faster transitions between different products or configurations.

A: SMED is important because it helps organizations reduce downtime and increase productivity. By implementing SMED techniques, companies can minimize the time spent on equipment changeovers, allowing for more production time and flexibility to meet customer demands. SMED also enhances operational agility, reduces costs associated with changeovers, and improves overall equipment effectiveness.

A: In the context of SMED, internal setup activities are tasks that can only be performed when the machine is stopped, such as disassembling components or adjusting settings. External setup activities, on the other hand, can be carried out while the machine is running, such as preparing tools, cleaning, or replenishing materials. Categorizing activities into internal and external helps in identifying opportunities to reduce downtime by converting internal activities into external ones.

A: SMED techniques include analyzing and documenting the setup process, dividing activities into internal and external, converting internal activities to external, standardizing setup procedures, eliminating adjustments and simplifying tasks, parallelizing activities, creating quick-change tools or mechanisms, implementing improvements, training employees, and monitoring and sustaining the changes over time.

A: SMED can benefit organizations in several ways. It helps reduce setup time, which in turn reduces downtime and allows for more production time. This increased operational efficiency can lead to higher productivity and improved customer responsiveness. SMED also reduces costs associated with changeovers, such as labor and inventory costs. It promotes a culture of continuous improvement and empowers employees to identify and address inefficiencies in the setup process.

A: Yes, SMED principles can be applied to various industries beyond manufacturing. The core concept of reducing setup time and increasing efficiency can be adapted to sectors such as healthcare, service industries, and logistics. For example, in a hospital setting, SMED can be used to optimize the time required to prepare and transition operating rooms between different procedures, leading to improved patient throughput and resource utilization.

A: The time required to implement SMED varies depending on the complexity of the setup process, the size of the organization, and the level of existing process documentation. It typically involves a step-by-step analysis of the current setup, identifying improvement opportunities, implementing changes, and training employees. The duration can range from several weeks to months, and it is an ongoing process of continuous improvement.

A: To get started with SMED, begin by understanding and documenting your current setup process. Analyze the activities involved and categorize them as internal or external. Look for opportunities to convert internal activities to external, simplify tasks, and create standardized procedures. Implement changes gradually, involving employees and providing training as needed. Monitor the results and continuously refine the setup process based on feedback and performance metrics. Consider seeking guidance from experts or consultants who specialize in lean manufacturing methodologies.

Author

Picture of Daniel Croft

Daniel Croft

Daniel Croft is a seasoned continuous improvement manager with a Black Belt in Lean Six Sigma. With over 10 years of real-world application experience across diverse sectors, Daniel has a passion for optimizing processes and fostering a culture of efficiency. He's not just a practitioner but also an avid learner, constantly seeking to expand his knowledge. Outside of his professional life, Daniel has a keen Investing, statistics and knowledge-sharing, which led him to create the website learnleansigma.com, a platform dedicated to Lean Six Sigma and process improvement insights.

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