What is SMED?
SMED, or Single-Minute Exchange of Die, is a Lean tool used in manufacturing to reduce equipment changeover time. The goal of SMED is to complete as many steps as possible while the equipment is running (or processing), to save time and quickly change over to processing the next product.
Each letter of this time-saving tool stands for a specific term, as follows:
- SM (Single-Minute) – ideally how long it should take to switch from making one product to another or “to exchange dies”
- E (Exchange) – switching from making one product to making another
- D (Die/s) – a specialized piece of equipment used to define the size and shape of a product
Do You Need this Tool?
Before going into the benefits of SMED or why manufacturers use it, it may be helpful to ask if SMED can be applied to your production process and if it’s the right Lean tool to use for making improvements.
To determine this, check if your current equipment changeover system satisfies the following factors:
- Do you have a system in place to measure manufacturing performance data?
- Does the system measure Overall Equipment Effectiveness (OEE)?
- Do you have at least 2 weeks’ worth of manufacturing performance data collected from the system?
- Based on the data, what percentage of lost productive time is from changeovers? IndustryWeek provides the formula for this as follows: Availability score = Available time ÷ Scheduled time
- Is the percentage of lost productive time from changeovers 20% or above?
- Do you have equipment that:
- employees are familiar with; and
- is a constraint?
- Is the changeover of this equipment:
- performed more than once each week;
- take an hour or so to complete on average; but
- can sometimes take much longer to complete (such as 2 hours more)?
Benefits
The main benefit of implementing SMED is reduced equipment changeover time, which creates a positive domino effect on other aspects of production. The five key advantages are:
- Increased capacity/machine work rates
- More frequent completions of equipment changeovers
- Reduced batch sizes / smaller lot sizes
- Reduced stock holdings / lower inventory levels
- Less space and handling required
- Less waste produced
- Standardized changeover procedures
- Less room for errors / improved quality
- Fewer defects produced
- Improved safety and consistency
- Lower production cost due to less planned downtime
3 Steps to the SMED Process
To help you get started with implementing SMED, here’s a quick 3-step guide on the SMED process:
Step 1: Separate
The first step in the SMED process is to separate changeover elements or group them according to their type (internal or external). Changeover elements are the steps taken to complete the equipment changeover. There are two types of changeover elements:
- Internal changeover elements – can only be done when the equipment is not processing anything
- External changeover elements – can be done while the equipment is running (or in the middle of processing something)
Identifying the type of changeover element is important because making as many steps (or changeover elements) external is how SMED reduces equipment changeover time.
Step 2: Convert
The second step in the SMED process is to convert internal changeover elements to external changeover elements. Once you’ve identified an internal changeover element that could be converted to external, ensure that the benefit (in terms of time saved) outweighs the cost of conversion (the resources needed to convert the changeover element to external).
A SMED technique for converting internal changeover elements to external ones is to use intermediate or duplicate jigs. The next product can be prepared using a jig (a kind of framework or mold) while the first product is being processed. The jig containing the prepared next product is then simply attached to the equipment.
Create your own SMED template
Step 3: Streamline
The third step in the SMED process is to streamline the internal changeover elements that weren’t converted to external. The fundamental SMED technique for this step is to follow the Lean principle of “trimming the fat” by removing inefficiencies from internal changeover elements. Simple and effective SMED techniques for this include the following:
- Try the 5S Lean method
- Organize the work area for maximum efficiency
- Use functional clamps
- Reduce the number of actions to only what is necessary
- Standardize parts or features
- Make performing internal changeover elements easier
- Eliminate adjustments
- Calibrate equipment to transition quicker
- Use standardized settings and fixed guides
SMED Examples
To give you a better idea of how the SMED process fits in your workplace or business, here are 2 SMED examples for manufacturing and restaurant settings:
SMED Example for Manufacturing:
| SMED Example 1 | ||
| Changeover | From Product A to Product B | |
| Equipment | Injection Molding Machine | |
| Time Equipment is Running | 480 minutes (8 hours of production before changeover) | |
| Time Equipment is Stopped | 30 minutes (Current changeover time between Product A and Product B) | |
| Elements: | ||
| Set up the equipment | Run the material changeover | Perform quality check on the product |
| Step 1: Separate | ||
| Internal | External | |
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| Step 2: Convert | ||
| Internal | External | |
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| Step 3: Streamline | ||
| Internal Streamlined | Streamlined the mold changeover process | |
| SMED Technique | Introducing quick-change mold systems, standardized procedures, and a set-up crew | |
SMED Example for Restaurants:
| SMED Example 2 | ||
| Changeover | Switching from lunch to dinner | |
| Equipment | Kitchen and staff | |
| Time Equipment is Running | When guests are being served | |
| Time Equipment is Stopped | When the restaurant is closed | |
| Elements: | ||
| Bring out ingredients for dinner menu meals | Clean the kitchen / prepare stations (throwing out oil, clearing chopping boards, etc.) | Ensure second shift (or dinner shift) servers are ready |
| Step 1: Separate | ||
| Internal | External | |
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| Step 2: Convert | ||
| Internal | External | |
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| Step 3: Streamline | ||
| Internal Streamlined | Optimized kitchen preparation and cleaning flow | |
| SMED Technique | Using 5S Lean method to organize the kitchen | |
FAQs about SMED
SMED is primarily a Lean manufacturing tool designed to reduce setup and changeover times in production processes. The ultimate goal is to achieve changeovers in less than ten minutes, hence the term “single-minute” in its name.
Despite fundamentally being a Lean tool, it can also be integrated into the Six Sigma methodology to enhance process efficiency and effectiveness.
Changeover is the transitioning of equipment from processing one product to processing another—which is very similar to the exchange of dies.
What the acronym SMED stands for describes the intended result of using this technique more so than the actual process of making the exchange of dies take less than 10 minutes (or of how to reduce equipment changeover time to less than 10 minutes).
The SMED technique gives manufacturers, Lean practitioners, SMEs, and service industries an advantage by reducing setup times, boosting productivity, lowering costs, and improving customer satisfaction. It promotes flexibility and waste reduction, ultimately leading to operational efficiency.
SafetyCulture Content Team
