What Is SMED? Reducing Changeover Time In Lean Manufacturing

what is smed

Changeover time—the interval required to switch a manufacturing line or equipment from producing one product to another—is crucial in determining a facility’s operational efficiency and productivity. Lean manufacturing, a methodology focused on minimizing waste and maximizing value, leverages techniques like reducing changeover times to enhance production flow and flexibility. By shortening these intervals, businesses can respond quicker to market changes and demands, leading to improved competitiveness and customer satisfaction.

SMED or single minute exchange of dies is a technique developed to specifically streamline changeovers and cut down the time they take - from hours to less than ten minutes. Adopting this technique can significantly improve facility efficiency and productivity. But how does the SMED process actually work? This article explores the concept of single minute exchange of die, its advantages, limitations, and step-by-step methodology.


What Is SMED?

industrial facility practicing lean manufacturing

Lean manufacturing is a systematic approach focused on enhancing value by optimizing processes, reducing costs, and improving quality. This strategy streamlines production and manufacturing processes and is capable of bringing significant changes in large-scale industrial operations.

Single Minute Exchange of Die (SMED) is a fundamental lean manufacturing tool primarily designed to optimize processes. The SMED method is aimed at reducing the amount of time a production machine is idle during changeovers. Contrary to common misconception, the term "single minute" does not imply that all changeovers and setups are completed in less than a minute, but rather that they are reduced to "single-digit minutes" (i.e., less than 10 minutes).

The core principles of the SMED procedure involve separating changeover elements into two categories: internal and external activities.

Internal activities are those that can only be performed when the production process is stopped, while external activities can be completed while the machine is still running or before the changeover begins. By converting internal activities into external ones, organizing workplace tools and components, and standardizing and streamlining processes, SMED helps achieve rapid setups and minimizes downtime.


Advantages of the SMED Method

Integrating the SMED method into changeover processes offers an array of benefits that significantly enhance manufacturing efficiency, agility, and overall productivity. Here are some of the key advantages of the SMED process:

  • Reduced Downtime - By minimizing the time machines are idle during changeovers, SMED directly decreases production downtime. This results in higher machine utilization and increased output, as more time is spent on actual production rather than setup.
  • Increased Flexibility - With quicker setups, manufacturers can switch between product types more frequently and efficiently. This flexibility allows for a more responsive production system, capable of adapting to changes in customer demands or market conditions without significant delays or disruptions.
  • Lower Inventory Costs - Faster changeovers mean that manufacturers can economically produce smaller batches, leading to reduced inventory levels. This not only cuts storage and holding costs but also reduces the risk of excess and obsolete stock.
  • Improved Quality - Shorter changeover times reduce the likelihood of errors typically associated with rushed or infrequent setups. By standardizing the setup processes, SMED also helps maintain consistent quality across production runs.
  • Enhanced Employee Engagement - SMED involves streamlining and clarifying processes, which often leads to clearer roles and responsibilities. This can improve worker satisfaction and engagement by making tasks easier and reducing the frustration associated with complex or inefficient procedures.
  • Better Safety - Simplified and standardized changeover procedures reduce the chances of accidents and mishaps. As setups become more routine and less rushed, the working environment becomes safer for employees.
  • Cost Efficiency - Beyond reducing direct operational costs through improved equipment utilization and inventory management, SMED can also lead to significant savings in labor costs and investment in additional equipment.


SMED Process: Step-by-Step Guide

smed process 5 step guide

Implementing the SMED (Single Minute Exchange of Die) process in lean manufacturing involves a series of structured steps designed to minimize setup times. Here’s a comprehensive step-by-step guide on how SMED works, along with some practical tips for effective implementation:

1. Determine pilot area for implementation

Begin by capturing every detail of the current setup process. This typically involves video recording and timing each activity to understand where time is spent. Observations should include not just the main activities but also the preparatory and finishing tasks that surround them.

Prioritize areas where changeovers are frequent and where reductions in setup time would have a significant impact on overall production efficiency. High-frequency areas offer more rapid and clear data on the effectiveness of SMED initiatives. Analyze current performance metrics such as downtime, rate of production, and setup time. Choose an area where improvements in these metrics would lead to noticeable benefits in production throughput and operational costs.

2. Identify key elements involved in the SMED procedure

Document every step, tool, and component involved in the current changeover process. This detailed observation should capture both the actions and the time taken for each, establishing a comprehensive baseline against which to measure improvements.

3. Separate external elements from internal elements

Analyze the identified elements and separate those that can be performed while the machine is running or before the changeover starts (external elements). This step focuses on reducing the machine downtime by moving as many activities as possible out of the changeover period.

4. Convert internal elements to external elements

The step of converting internal elements to external elements is one of the most critical components of the SMED method. This process aims to reduce machine downtime by shifting as many setup activities as possible from internal (done while the machine is stopped) to external (done while the machine is running or before it stops).

Begin by listing all internal activities identified in the initial documentation phase. Analyze each task to determine if it absolutely requires the machine to be stopped, or if it’s done internally only due to current procedural habits or constraints. Then, identify opportunities for change. More specifically, find ways to perform internal elements externally. This might include:

  • Questioning the traditional workflow and getting creative with solutions
  • Determining if the activity can be prepared in advance, if tools can be set up beforehand, or if adjustments can be made while the machine is still operational.
  • Investing in tool modifications to allow for external operations
  • Reconfiguring workspace layout to allow for a more effective and efficient flow of processes during changeover.

However, the most important part of this step is to develop a standard operating procedure for the tasks that are converted from internal to external. Furthermore, it is critical to ensure that all team members are briefed and trained in the new procedures. Once changes are implemented, it is essential to document the process and compare it to earlier gathered data. Regularly review the converted processes to ensure they are still effective and to identify any new opportunities for further conversion from internal to external.

5. Streamline Remaining Elements

For the elements that must remain internal, streamline these processes to reduce their complexity and duration. Techniques might include simplifying tasks, introducing quicker-connecting components, or creating better organizational tools like shadow boards to minimize search and retrieval times.

Additional Tips for Effective SMED Implementation:

  • Engage Operators Early: Involving machine operators and other frontline staff early in the SMED process can provide insights that might not be obvious to managers or engineers.
  • Implement a Pilot Program: Before rolling out changes across the board, test them on one machine or production line to evaluate their effectiveness and make adjustments based on real-world feedback.
  • Leverage Technology: Consider using modern technologies such as IoT sensors, AI, or machine learning to gather data and provide insights into further efficiencies in the setup process.
  • Celebrate Successes: Recognize and reward the team for successful reductions in setup times. This not only boosts morale but also encourages ongoing participation in lean initiatives.


SMED Examples in Industrial Facilities

The SMED method has been successfully implemented across a variety of industries, demonstrating its versatility and adaptability. Here are examples of how SMED has been applied in different settings, highlighting the adjustments and changes made to suit specific industry needs:

Automotive Manufacturing

In car assembly lines, SMED has been used to reduce the time taken to switch die sets in stamping machines. Modifications such as pre-staged dies, quick-release mechanisms, and standardized procedures have reduced changeover times from several hours to under ten minutes. The impact extends to reducing inventory levels of in-process parts, enabling a smoother flow and quicker response to model changes based on consumer demand.

Food and Beverage Processing

The food industry often requires frequent changeovers due to the variety of products processed on the same equipment. SMED principles have been applied to reduce setup times by simplifying and standardizing cleaning processes, using mobile cleaning stations, and training staff in rapid setup techniques. This has resulted in increased production time, reduced waste from fewer startup errors, and improved ability to meet fluctuating market demands.

Electronics Assembly

In electronics, where production lines must switch frequently between products, SMED has facilitated the rapid exchange of component feeders and adjustment of placement machines. Implementing shadow boards for tools and pre-set jigs for quick loading and unloading of production materials are common practices. These changes have significantly reduced changeover times, increased line uptime, and allowed for more flexible production scheduling.


Limitations to the SMED Method

While the SMED strategy offers significant benefits in reducing changeover times and enhancing productivity, it is not without limitations. Understanding these limitations and considerations is crucial for determining if SMED is appropriate for a specific manufacturing setting and for implementing it effectively

Determining if SMED is Appropriate

In some industrial settings, the adaptation of the SMED procedure may not be feasible. Here are some key considerations to help determine if SMED is applicable to your needs:

  • Complexity of Equipment: SMED is most effective when the equipment or processes involved are amenable to quick changes. In cases where machinery is highly complex or requires significant calibration, the benefits of SMED might be limited.
  • Scale of Operation: For very small operations, the investment in resources to implement SMED may not justify the gains. Conversely, in very large operations, the logistical challenges of coordinating an SMED initiative might be daunting.
  • Product Variety: High variability in products might require more substantial modifications to the SMED approach, potentially complicating its implementation.

SMED Method Challenges & Limitations

The SMED method, when implemented properly, is a powerful tool in lean manufacturing for reducing changeover times. However, the strategy itself comes with challenges and limitations that can hinder its implementation.

For one, implementing SMED often requires significant investment in resources such as redesigning equipment to allow for quicker changeovers, purchasing specialized tools or fixtures, and adapting existing workflows. This can be a substantial financial barrier for smaller operations or those with limited capital. Beyond physical modifications, there's a need for extensive training and retraining of staff to familiarize them with the new processes and techniques. After the initial significant gains in reducing setup times, further improvements can become increasingly marginal. This means that SMED only provides incremental improvements that offer seemingly diminishing returns.

Another limitation to the SMED method revolves around employee engagement. Changes in procedures and roles can meet with resistance from employees who are accustomed to certain ways of working. If the workforce is not adequately engaged or convinced of the benefits, there might be a lack of enthusiasm or outright resistance to adopting SMED principles.

With the SMED methodology, there are also risks associated with the overemphasis on speed. Focusing intensely on reducing setup times can inadvertently lead to compromises in quality if not properly managed. Continuously pushing for faster setups can place undue pressure on employees, leading to stress and potential burnout.


Single Minute Exchange of Die (SMED) FAQs

What is the concept of Lean?

Lean is a systematic approach to workflow management that aims to streamline manufacturing, service, or administrative processes by reducing waste and improving efficiency. The goal is to enhance value for the customer through continuous improvement.

What is the meaning of changeover period?

The changeover period refers to the time taken to switch a production system or line from making one product or variant to another. This includes the time to adjust equipment, replace tools or dies, and reconfigure settings.

What is an example of lean manufacturing?

An example of lean manufacturing is the implementation of the Just-In-Time (JIT) inventory system, where materials and products are produced or delivered only as needed, reducing inventory costs and increasing efficiency.

What is the target time for SMED?

The target time for SMED (Single Minute Exchange of Dies) is to reduce changeover times to less than 10 minutes, ideally within single-digit minutes, to minimize production downtime and enhance flexibility.

How does SMED achieve waste reduction in a Lean process?

SMED achieves waste reduction by minimizing the non-productive time and activities during changeovers, such as waiting, unnecessary movements, or extended machine downtime. By optimizing and streamlining changeover tasks, SMED helps maintain continuous flow and productivity in the production process, which are key principles in Lean methodology.


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The material provided in this article is for general information purposes only. It is not intended to replace professional/legal advice or substitute government regulations, industry standards, or other requirements specific to any business/activity. While we made sure to provide accurate and reliable information, we make no representation that the details or sources are up-to-date, complete or remain available. Readers should consult with an industrial safety expert, qualified professional, or attorney for any specific concerns and questions.


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Author: Herbert Post

Born in the Philadelphia area and raised in Houston by a family who was predominately employed in heavy manufacturing. Herb took a liking to factory processes and later safety compliance where he has spent the last 13 years facilitating best practices and teaching updated regulations. He is married with two children and a St Bernard named Jose. Herb is a self-described compliance geek. When he isn’t studying safety reports and regulatory interpretations he enjoys racquetball and watching his favorite football team, the Dallas Cowboys.