SMED - Single Minute Exchange of Dies

SMED - Single Minute Exchange of Dies = Minimizing change over time

Example:

Motorsports

The Formula 1 or NASCAR Pit Stop is the ultimate real-time, live example of SMED principles in action.

• The Process: Changing four tires and refueling (or making quick adjustments).

• SMED Principles Applied:

  • Pre-Staging (External): All tools (impact wrenches), tires, and personnel are pre-positioned and waiting before the car arrives.

  • Standardization & Elimination (Streamlining): Tools are designed for quick use (e.g., a single large wheel nut instead of five small ones), and every step is choreographed and trained for parallel operation.

  • Parallel Operation: Multiple team members work simultaneously on different tasks (one person per wheel, another on the jack, another on the nose).

• Result: A complete changeover (pit stop) is performed in under 10 seconds, often in as little as 2-3 seconds, where every fraction of a second is critical to success.

What is SMED?

Single Minute Exchange of Dies (SMED) is a theory and set of techniques that make it possible to perform equipment set-up and change-over operations in under 10 minutes.

Key Definition

Set-up or Change-Over Time is defined as the elapsed time from the completion of the last good part of the last job (batch) to the completion and verification of the first good part of the next job.

Common SMED Solutions

SMED implementations often use the following types of solutions:

• Standardised tooling - Using consistent, interchangeable tools across operations
• Quick fit connectors - Fast-attachment mechanisms that eliminate threading or complex fastening
• Tooling held at point-of-use - Keeping tools and equipment right where they're needed
• Change-over 'teams' - Dedicated groups trained in rapid changeover procedures
• Poka Yoke and 5S contribute - Error-proofing devices and workplace organization methods that support faster, mistake-free changeovers

The goal of SMED is to reduce manufacturing downtime, increase flexibility, and improve overall equipment effectiveness by minimizing the time lost during product or tool changes.

Employing SMED will enable you to:

Increase Flexibility: Companies can meet the changing customer needs without the expense of excess inventory.

Enable Quicker Delivery: Small-lot production means less lead time and less customer waiting time.

Improve Quality: Less inventory storage means fewer storage-related defects. SMED also lowers defects by reducing setup errors and eliminating trial runs of the new product.

Generate Higher Productivity: Shorter changeovers reduce downtime, which means a higher equipment productivity rate.

Improve Safety: Simpler setups result in safer changeovers, with less physical strain or risk of injury.

Steps to perform SMED:

The process for performing SMED typically involves the following core steps:

1. Observe and Analyze the Current Process

• Team Formation: Assemble a cross-functional team (operators, maintenance, engineering, supervisors, etc.).

• Documentation: Select a changeover to study and document every step of the current process, including how long each step takes. Video recording is often used for accurate analysis.

• Baseline: Determine the total changeover time (from the last good part of the previous run to the first good part of the next run, running at full speed).

2. Separate Internal and External Activities

• Classification: Go through the documented steps and classify each as either:

  • Internal (I): Activities that must be performed only when the machine is stopped.

  • External (E): Activities that can be performed while the machine is running (before the stop or after the start).

3. Convert Internal Activities to External Activities

• Re-evaluate: Scrutinize every internal activity to find ways to perform it while the machine is still running or before the machine stops.

  • Examples: Pre-heating tools, preparing materials, staging and inspecting tools/dies/molds, and gathering all necessary documentation/gauges before the machine is shut down.

• Implement Changes: Redesign the process and make necessary physical and procedural changes to enable these conversions.

4. Streamline and Simplify All Remaining Activities

• Streamline Internal (I) Activities: Focus on making the remaining tasks that must be done while the machine is stopped as fast as possible.

  • Techniques: Replace bolts with quick-release clamps/mechanisms, standardize dimensions (like die height) to eliminate adjustments, or use parallel operations (two people working simultaneously).

• Streamline External (E) Activities: Optimize the external activities for speed and efficiency to ensure they are completed on time.

  • Techniques: Organize tools using the 5S method, create pre-kitted carts with all materials, and define clear responsibilities.

5. Standardize, Document, and Train

• Documentation: Create clear, standardized work procedures (SOPs) for the new, optimized changeover process.

• Training: Train all relevant personnel on the new standard procedures to ensure consistency.

• Checklists: Develop "pre-flight" checklists to ensure all external steps are completed before the machine stops.

6. Continuous Improvement

• Measure and Track: Regularly measure and track the new changeover time to ensure the gains are sustained and to identify further opportunities for improvement.

• Repeat: SMED is a continuous process. Re-apply the steps to further refine the changeover time, pursuing even greater reductions.