SMED: A Guide

Everything you need to know about SMED: its meaning, how to apply the SMED process in 3 steps, and SMED examples to help guide you

Published 22 Jul 2021

What is SMED?

Single-Minute Exchange of Dies (SMED) 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), so as to save time and quickly change-over to processing the next product.

Single-Minute Exchange of Dies (SMED) Meaning

Before learning more about this time-saving tool, it’s necessary to understand what each term of the acronym means. The last letter, D, stands for dies/die. In manufacturing, a die is a specialized piece of equipment used to define the size and shape of a product. A die is best described as a stamp or an industrial cookie-cutter.

Moving on to the second-to-last letter, E stands for exchange of dies. Since a die is customized to create a certain size and shape, the die of one product would be different from the die of another. Therefore, exchanging dies simply means switching from making one product to making another.

The remaining two letters, SM, stand for single-minute, which is ideally how long it should take to switch from making one product to another or “to exchange dies”. However, this can be modified to mean single-digit minute exchange of dies (less than 10 minutes exchange of dies).

SMED and Equipment Changeover Time

Now that the exact meaning of SMED has been discussed, another thing to clarify before considering SMED is how it’s related to equipment changeover time. Changeover is the transitioning of equipment from processing one product to processing another. It’s very similar to the exchange of dies (defined in the previous section). 

An interesting thing about SMED is that what it stands for (single-digit minute exchange of dies) describes the intended result of using SMED more so than the actual process of how to make the exchange of dies take less than 10 minutes (or of how to reduce equipment changeover time to less than 10 minutes).

Do You Need SMED?

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. The following are factors you need to consider before implementing SMED:

  1. Do you have a system in place for measuring manufacturing performance data?
    If you don’t have a system, consider using iAuditor by SafetyCulture, a powerful inspection platform built for teams and used by industry leaders.
  2. Does the system measure Overall Equipment Effectiveness (OEE)?
    OEE is a manufacturing industry gold standard for spotting inefficiencies of equipment and of production processes involving it. OEE looks at 3 factors (availability, performance, quality) and calculates the score of each factor, with the combined score being the OEE score. 
  3. Do you have at least 2 weeks worth of manufacturing performance data collected from the system?
  4. Based on the data, what percentage of lost productive time is from changeovers?
    To help determine this, it’s recommended to take a closer look at the breakdown of the availability score, as seen in the example provided by IndustryWeek below:

    Availability score = Available time ÷ Scheduled time

    Available time:

    Scheduled time:

    Downtime (Lost Productive Time):

    Scheduled time 
    – Downtime

    Gross available time 
    Planned downtime

    +Breakdowns 
    +Setups and adjustments 
    +Minor stoppages

    Changeovers are known to add to setups and adjustments (planned downtime), one of the Six Big Losses that negatively impact manufacturing productivity.

  5. Is the percentage of lost productive time from changeovers 20% or above?
    If the percentage is less than 20%, a Total Productive Maintenance (TPM) program is recommended, instead of SMED.
  6. Do you have equipment that (a) employees are familiar with and (b) that is a constraint?
  7. Is the changeover of this equipment (c) performed more than once each week, (d) takes an hour or so to complete on average, (e) but can sometimes take much longer to complete (such as 2 hours more)?

If you have answered yes to the questions above, you can begin implementing SMED on the equipment changeover.

What You Can Gain From Implementing SMED

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 benefits are:

  1. Increased capacity / machine work rates 
  2. Equipment changeovers completed more often 
  3. Reduced batch sizes / smaller lot sizes
    • Reduced stock holdings / lower inventory levels 
    • Less space and handling required
    • Increased flexibility to address customer needs
    • Less waste produced
  4. Standardized changeover procedures 
    • Less room for errors / improved quality
    • Fewer defects produced 
    • Improved safety and consistency
  5. Lower production cost due to less planned downtime

Simplified SMED Process

SMED steps

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 are the steps that can only be done when the equipment is not processing anything 
  • External changeover elements are the steps that 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.

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 4 SMED examples which show that it can be used even in industries outside of manufacturing:

SMED Examples for Restaurants:

SMED Example 1
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

  • clean the kitchen / prepare stations (throwing out oil, clearing chopping boards, etc.)
  • ensure second shift (or dinner shift) servers are ready
  • bring out ingredients for dinner menu meals

Step 2: Convert

Internal

External

  • clean the kitchen / prepare stations
  • bring out ingredients for dinner menu meals
  • second shift servers come in already prepared or prepare while the first shift servers are almost done

Step 3: Streamline

Internal Streamlined

optimized kitchen preparation and cleaning flow

SMED Technique

using 5S Lean method to organize the kitchen

SMED Example 2
Changeover

Preparing meal A to preparing meal B

Equipment

Cooking tools and ingredients

Time Equipment is Running

stove is on / chef is cooking

Time Equipment is Stopped

stove is off / chef is not cooking

Elements:

moving to pantry to get ingredients for meal B

looking for cooking tools to use for meal B

prepping cooking tools for use (preheating, etc.)

Step 1: Separate

Internal

External

  • moving to pantry to get ingredients for meal B
  • looking for cooking tools to use for meal B
  • prepping cooking tools for use (preheating, etc.)

Step 2: Convert

Internal

External

  • moving to pantry to get ingredients for meal B
  • look for cooking tools while meal A is on the stove
  • prepping cooking tools for use (preheating, etc.)

Step 3: Streamline

Internal Streamlined

meal B ingredients are placed near the cooking station

SMED Technique

use functional clamps

SMED Examples for Hospitals:

SMED Example 3
Changeover

Operating room and patient room/bed turnover

Equipment

Operating room and patient room/bed

Time Equipment is Running

when operating room or patient room/bed is in use

Time Equipment is Stopped

when operating room and patient room/bed not in use

Elements:

cleaning operating room and patient room (surface cleaning)

disinfecting operating room, patient room/bed

preparing operating room and patient room/bed for next use

Step 1: Separate

Internal

External

  • disinfecting operating room, patient room/bed
  • cleaning operating room and patient room (surface cleaning)
  • preparing operating room (medical tools for next surgery)

Step 2: Convert

Internal

External

  • disinfecting operating room, patient room/bed
  • preparing operating room
  • start a bit of cleaning while operating room and patient room is in use

Step 3: Streamline

Internal Streamlined

standardized disinfection procedures are followed

SMED Technique

standardize parts or features

SMED Example 4
Changeover

Going from hospital to person in distress (emergency medical care)

Equipment

EMT, ambulance driver, medical equipment/supplies

Time Equipment is Running

when the ambulance is on the way to the person

Time Equipment is Stopped

when the ambulance is waiting in the parking lot

Elements:

looking for the tools or machines needed for emergency medical care

moving ambulance out of hospital parking lot

getting EMT inside the ambulance

Step 1: Separate

Internal

External

  • moving ambulance out of hospital parking lot
  • getting EMT inside the ambulance
  • looking for common tools (in first aid kit)

Step 2: Convert

Internal

External

  • moving ambulance out of hospital parking lot
  • looking for common tools (in first aid kit)
  • assigning EMT to areas in the hospital that are near the ambulance vehicles/parking lot

Step 3: Streamline

Internal Streamlined

ensure that ambulances are parked near the exit of the hospital parking lot and positioned in a way that the ambulance driver can get the ambulance out of the parking lot with minimal movements or actions

SMED Technique

eliminate adjustments

Using iAuditor to Make SMED Work For You

iAuditor by SafetyCulture is a powerful inspection platform that’s built for teams. Conduct inspections of equipment, processes, and anything else you can think of with iAuditor. View performance data in Analytics and see the average score of inspections, letting you know which changeovers are in need of improvement. Beyond that, iAuditor can make SMED work for you, and not the other way around. Here’s how:

  • Customize the SMED template below. You can add and delete sections and pages.
  • Document equipment changeovers digitally, even when you’re not there. Workers can take photos and add notes and the inspection will update automatically on all your devices.
  • Monitor the effects of implementing SMED across your entire business, if the shortened changeover improved other statistics, and if not, edit the SMED template or inspection to reflect your findings and/or repeat the SMED process.
  • Implement the SMED process on multiple equipment changeovers with just one premade, customizable SMED template.

 

SafetyCulture Content Specialist

Zarina Gonzalez

Zarina is a content writer and researcher for SafetyCulture. She enjoys discovering new ways for businesses to improve their safety, quality, and operations. She is working towards helping companies become more efficient and better equipped to thrive through change.

Zarina is a content writer and researcher for SafetyCulture. She enjoys discovering new ways for businesses to improve their safety, quality, and operations. She is working towards helping companies become more efficient and better equipped to thrive through change.