SMED Technique

SMED (Single-Minute Exchange of Die) is a technique used in the Lean system. Developed by Shigeo Shingō within the Toyota Production System, it focuses on reducing machine setup time, with the aim of improving production flow. 

Definition and stages of setup

Setup, or tooling, refers to the set of activities required to prepare a production facility for use. It involves the substitution and/or modification of certain components and parameters to enable the production of a different product. 

Two types of setup activities are identified: 

• Internal activities (IED – Inside Exchange of Die): Activities that must be carried out while the machine is stopped. For example, changing a machine component. 

• External activities (OED – Outside Exchange of Die): Activities that can be performed while the machine is running. For example, preparing necessary materials. 

The activities are further divided into four categories: 

• Preparation (P): Preparing everything that needs to be changed and/or used during downtime (e.g. machine parts, tools, materials, documents). 

• Changeover (C): Replacing components used for the previous batch with those required for the new one. 

• Adjustments (R): Setting machine parameters such as centering, temperature, or pressure. 

• Testing (T): Performing trials or adjustments. 

Applying the SMED technique: Operational steps

The goal of the SMED technique is to minimise setup time by converting as many internal activities as possible into external ones, thereby optimising production flow and increasing efficiency. The method is applied in six phases, each contributing to the progressive optimisation of the tooling process. 

Step 0 - Analysis of the existing setup.

Start by collecting data and information about the current setup process, asking key questions: 

• Have the machine-related processes been mapped? 

• How many different finished products pass through the machine? 

• Does the machine’s capacity meet demand? 

• What is the target lead time? 

To support the analysis, a video of the setup is recorded, and each activity is reviewed in detail: who performs it, how long it takes, the type of activity (Preparation - Change - Adjustment - Test, P-C-R-T), and the tools needed. 

Step 1 - Separation of internal and external activities.

Distinguish activities that can be performed while the machine is running (OED) from those that require downtime (IED). This is the first step in reducing non-productive time. 

Step 2 - Optimization of external activities

OED activities are reorganised to be more efficient. Some actions (e.g. retrieving materials for the next batch) are anticipated, while others (e.g. transporting finished products to the warehouse) are postponed. The aim is to eliminate any unnecessary activity during setup.

Step 3-Reduction of adjustments and testing.

Minimise time spent on adjustments and testing by standardising critical variables using: 

• Jigs and gauges for rapid setup; 

• Position indicators and machine parameter sheets; 

• Pre-heating or pre-assembly of moulds. 

The objective is to reduce the number of trials and start production with parameters already optimised. 

Step 4 - Reducing changeover time

Action is taken on component changeover activities to minimise tooling time. Some of the most effective solutions include: 

• Quick-fix systems; 

• Standardisation of screws to reduce the number of tools required; 

• Replacing manual wrenches and screwdrivers with electric screwdrivers. 

Step 5 - Optimizing external activities and maintaining results

This final phase improves the organisation of materials, tools, and equipment without affecting downtime. Key questions to consider include: 

• How can tools and materials be organised more effectively? 

• How can they be maintained in a ready-to-use state? 

Once optimisations are complete, it is essential to standardise the process to ensure the sustainability of the improvements made. Clear operational standards should define: 

• The exact sequence of operations; 

• Who performs each task, with which tools and PPE; 

• The expected duration of each activity. 

Finally, performance must be monitored using specific KPIs related to setup time. Visual management tools can support immediate progress tracking and prompt timely problem- solving actions in case of deviations from targets. 

Benefits of the SMED technique

• Efficient batch management and cost reduction: Faster changeovers allow for smaller batch sizes, reducing inventory costs, waste, and lead time, while improving customer service. In addition, the ability to customers who are not willing to purchase large lot opens up new markets. 

• Standardisation and optimisation of procedures: One of the outputs of the SMED technique is the implementation of standardised procedures that help maintain target times and support the training of new operators.

You can find practical examples of this technique in our  Case Histories!