SMED (Single-Minute Exchange of Dies): Meaning, Purpose, Benefits, Method, Application, and Example

SMED is a lean manufacturing technique aimed at reducing the time it takes to change over equipment or processes, thus improving flexibility, reducing downtime, and increasing production efficiency. The goal is to reduce changeover time to under 10 minutes (hence “single-minute”), thereby increasing the availability of equipment and the overall capacity of the production process.

1. Meaning of SMED:

• SMED (Single-Minute Exchange of Dies) is a process improvement methodology developed by Shigeo Shingo as part of the Toyota Production System (TPS).
• It focuses on reducing changeover time (the time it takes to switch from producing one product to another) in manufacturing processes. This could be switching dies in presses, changing molds in injection molding machines, or reconfiguring machinery in other processes.
• The primary objective is to reduce downtime during these transitions, improving flexibility, and making it possible to switch between different products more quickly and with minimal waste.

2. Purpose of SMED:

• Reduce Changeover Time: The main purpose of SMED is to reduce the time required for equipment setup or changeover, thus increasing equipment utilization.
• Improve Flexibility: By reducing changeover times, it becomes easier to switch between different product types or variations, allowing manufacturers to be more flexible and responsive to market demand.
• Increase Production Efficiency: With reduced downtime, the overall capacity of production increases, leading to greater output with the same resources.
• Facilitate Smaller Batch Production: Shorter changeover times enable the production of smaller batch sizes, which is crucial for just-in-time (JIT) manufacturing and reducing inventory levels.
• Enable Continuous Improvement: The SMED approach fosters a mindset of continuous improvement by focusing on reducing waste and increasing the speed of processes.

3. Benefits of SMED:

• Increased Equipment Utilization: By reducing changeover time, machines and equipment are idle for shorter periods, thus improving overall machine utilization.
• Higher Production Rates: Shorter changeover times result in more time spent on actual production, leading to increased production rates and output.
• Reduced Inventory: With quicker changeovers, manufacturers can produce smaller batches and maintain lower levels of inventory, leading to reduced storage costs and waste.
• Enhanced Flexibility: SMED allows for quick changes between product types, enabling manufacturers to respond rapidly to customer orders or changing market conditions.
• Improved Product Variety: By reducing changeover times, manufacturers can more easily produce different variants or models, increasing the diversity of products that can be offered.
• Cost Savings: Faster changeovers reduce downtime and improve resource efficiency, which can translate into lower operational costs and better profitability.

4. Method of SMED:

The SMED methodology is typically divided into several steps, focusing on transforming internal setup activities (those that can only be performed while the machine is down) into external activities (those that can be performed while the machine is running). Here’s a step-by-step outline of the method:

1. Identify and Analyze Setup Activities:
   • Start by recording and analyzing all the steps involved in the current changeover process.
   • Break down the changeover into internal and external activities.
     • Internal activities are tasks that must be performed while the machine is stopped (e.g., changing dies or adjusting settings).
     • External activities are tasks that can be done while the machine is running (e.g., preparing tools, cleaning parts, or reviewing the next batch’s specifications).
2. Separate Internal and External Activities:
   • Internal activities: Identify which tasks can be eliminated, simplified, or re-engineered.
   • External activities: Determine which internal tasks can be converted into external ones, allowing them to be completed while the machine is still operating.
3. Convert Internal Activities to External Activities:
   • The goal is to convert as many internal activities as possible into external ones by organizing tools, preparing materials, and pre-setting equipment before the machine is stopped.
4. Streamline and Simplify Internal Activities:
   • For the remaining internal activities (those that must be done while the machine is stopped), focus on reducing their complexity and time.
   • This can be achieved by using quick-change tooling, standardized tools, and improving the organization of work areas.
5. Standardize the Changeover Process:
   • Create standardized work procedures for the new, improved changeover process.
   • Training should be conducted to ensure that all operators are familiar with the new methods and the tools needed for fast changeovers.
6. Continuous Improvement:
   • Even after implementing SMED, continue to look for further improvements and refine the changeover process.
   • Use the lessons learned from each changeover to refine procedures and reduce time even further.

5. Application of SMED:

SMED can be applied to a wide range of industries and manufacturing processes. Some of its common applications include:

• Automotive Manufacturing: In automotive plants, SMED is used to reduce the time required to change stamping dies or molds in production lines, allowing for greater flexibility in producing different vehicle models.
• Injection Molding: In injection molding plants, SMED is applied to reduce the time required for changing molds, which is a key factor in improving the efficiency of production and reducing waste.
• Food and Beverage: In the food processing industry, SMED can be applied to reduce downtime during batch changeovers, increasing throughput and reducing product changeover times (e.g., switching between different flavors or product types).
• Printing and Packaging: In printing and packaging lines, changeovers between different packaging sizes or designs can be optimized using SMED principles, reducing downtime and increasing production flexibility.
• Pharmaceutical Manufacturing: In pharmaceutical production, SMED can reduce the downtime associated with switching between different drug formulations, which is crucial for maintaining high throughput while ensuring quality.

6. Example of SMED in Practice:

Example 1: Automotive Manufacturing

• Problem: An automotive company’s assembly line experiences long setup times when switching between different car models. This results in significant downtime and reduced production capacity.
• Application of SMED:
  1. The company analyzes the setup process and finds that many activities (like preparing tools and materials) are done after the production line has been stopped, contributing to long changeover times.
  2. By re-engineering the setup process, they move as many activities as possible to be done before the machine stops (such as pre-heating tools, preparing materials, and cleaning dies in advance).
  3. They also implement quick-change dies, so the actual time spent changing over equipment is minimized.
  4. Through these improvements, changeover times are reduced from 90 minutes to under 10 minutes, allowing for more frequent model switches and greater overall productivity.
• Outcome: The company achieves increased flexibility, a reduction in downtime, and an increase in the variety of car models produced without sacrificing production speed.

Example 2: Injection Molding

• Problem: A manufacturer of plastic products using injection molding machines experiences long changeover times between different molds, leading to high machine downtime.
• Application of SMED:
  1. The company identifies that many tasks, such as retrieving tools and adjusting settings, are done only during machine downtime.
  2. They convert several internal activities (like preparing molds and checking specifications) into external activities (by pre-setting molds, cleaning tools, and organizing materials before the changeover).
  3. Additionally, the company introduces standardized, quick-change molding systems that reduce the time spent on mold changes.
• Outcome: Changeover times are reduced from 60 minutes to 15 minutes, leading to a more efficient and productive molding process.

Conclusion: SMED (Single-Minute Exchange of Dies) is an effective methodology for reducing changeover times and improving production flexibility. By focusing on reducing downtime during setup processes, SMED allows businesses to increase throughput, reduce waste, and improve operational efficiency. Its application is valuable in industries where frequent product changes are needed, such as automotive, food processing, injection molding, and pharmaceuticals. Implementing SMED leads to better resource utilization, enhanced flexibility, and significant cost savings, ultimately boosting overall production efficiency.