Introduction to SMED: A Neglected Method in Lean
Construction
leanconstructionblog.com/Single-Minute-Exchange-of-Dies-A-Neglected-Method-in-Lean-Construction.html
by Algan Tezel
SMED, short for Single-Minute Exchange of Dies, refers to a method in the Lean
Production System that is used for quick, simplified and efficient production set-up and
changeover from one product/process to another, which often constitute the major causes
of production downtime (non-productive time/stoppages)1. It is one of the foundational
blocks of a continuous, improved production flow. The phrase "single minute" does not
mean that all changeovers and setups should take only one minute, but that they should
take less than 10 minutes (in other words, "single digit minute")2. The “Dies” refer to
specialized tools used in manufacturing industries to cut or shape material mostly using a
press, which need to be modified and re-setup when a production model is changed.
Changing dies could stop processes for an extended amount of time.
Car racing is often used as a metaphor for SMED, with process setups/changeover as pit
stops. In fact, many of the pit stop tricks are used in SMED, from prepositioning
everything you need to using quick attach and release tools (see the following video).
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Watch Video At: https://youtu.be/LOJbM0aXZp0
The video contrasts a Formula 1 racing pit stop at the Indianapolis 500 in 1950 with one
in 2013 in Melbourne, Australia. The time the car was stopped reduced from 67 to 3
seconds. The 1950 pit stop used 4 people for 67 seconds, which sums up to 4 minutes and
28 seconds of labor. If we include the external setup — before the car arrives — and the
cleanup afterwards, the 2013 pit stop used 17 people for 44 seconds, or 12 minutes and 28
seconds of labor. In terms of labor costs, the 2013 pit stop was therefore more “costly.” In
a race, however, cutting the car stoppage time by a factor of 22 is something invaluable 2.
Main Steps
SMED has applications in construction too and needs to be thought through in a different
way. The problem to be addressed is how can one reduce the set-up to complete a
particular task. Therefore, construction practitioners need to understand the core of
SMED with its techniques in Lean production and adopt them to their work contexts.
Good questions to ask are4:
What can we do before we get to the workplace that will make work at the point of
assembly safer, faster, cheaper, etc.?
What can we do while subsequent teams are at the workplace?
How can we reduce the time we spend at the workplace?
As an introduction to the topic, we will just give the main steps to SMED, which are5,6,7:
1) Observe the current methodology:
Current procedures generally are recorded on video tape of all the setup/ changeover
process. Get an activity or process where the changeovers/setups take a long time and the
variability is high. Be sure to capture both “human” elements (elements where the
operator is doing something) and “equipment” elements (elements where the equipment
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is doing something). A simple table can be created to investigate the setup/ changeover
process (describing activities, activity durations, activity reparations, activity types Internal or External):
Figure 1. An exemplary setup preparation sheet - setup activities, activity durations,
repetitions and activity types (Internal or External) recorded.
2) Separate the Internal and External activities:
internal activities are those that can only be performed when the process is stopped (i.e.
setting-up the supporting legs of a mobile crane), while external activities can be done
while the process is on-going (i.e. getting the equipment ready for the lifting operation slings etc can be done before the machine is shut down). The key question here is “Do I
have to shut the machine/process down to perform this activity?”. Some prime candidates
for external activities are retrival (parts, tools, materials etc), inspection, cleaning and
quality checks. Using post-its to discuss with your team whether activities are internal or
external can help.
Figure 2. Decide on Internal(I) and External(E) activities with your team using Post-Its
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3) Converting the Internal activities to External activities:
For construction, this conversion can be achieved by preparing staff, activity, tool and
information planning. Some things to consider are: positioning, on-site tool/equipment
configuration, small prefabrications/ tweaks (e.g. prefabricated blocks of competents
coming on-site with hooking protrusions), modularization, tool tweaking, increasing onsite process transparency and information flow etc. The question is: If there was a way to
make this element external, what would it be? How could we do it?
4) Stream line the process of changeover/setup:
For each iteration of the above process, a substantial improvement in set-up times should
be expected, so it may take several iterations. In this step, the remaining internal set-up
items are reviewed with an eye towards streamlining and simplifying. Eliminating motion,
waiting, adjustments, creating parallel operations, standardizing hardware are typical in
this step. The question: How can this element be completed in less time? How can we
simplify this element?
5) Continuous training:
After the successful first iteration of SMED application the prime requirement becomes
training of all the team members.
A SMED Case from Construction
A SMED implementation for quick setup preparation in construction came from the
Manchester Smart Motorways site in the UK8. The project’s Lean Construction team
streamlined their chamber installation for underground utilities, a critical task in their
project, by studying the installation process setup and externalising some internal
activities. The team mainly studied and re-configured the longitudinal site layout and
material interface, removed site obstructions with better coordination and preparation,
prepositioned components and re-designed a HIAB truck with a trailer to carry and install
materials simultaneously for quick attach (see images below)8:
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Figure 3. Improved material lay-down on an ideal model
Figure 4. Modified HIAB
The benefits obtained from those simple looking modifications are certainly not minor,
especially when the repetitive nature and importance of those tasks to the project are
considered. The SMED process led to:
Increased productivity from 1.5 chambers in 2 days to 2 per day (167% productivity
increase)
Significant increase in the percentage of value adding activities, improved process
flow and waste reduction
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Conclusion
Although described as an essential method in Lean, systematic SMED studies in
construction have received little attention. This may be in part due to the
misinterpretation that it is an exclusively manufacturing concept. This blog post aims at
increasing the practitioners’ awareness of the topic and prompting them to give some
thought to SMED opportunities in their work environments. Construction operations
could also be improved through learning from many sophisticated SMED examples from
other industries. The key here is to recognize the opportunities for SMED and asking the
right questions. The author would like to see more SMED stories from construction. In
future posts, some practical details of SMED applications and construction SMED cases
could be discussed in more detail.
References
1. Dillon, A. P., & Shingo, S. (1985). A revolution in manufacturing: the SMED system.
CRC Press.
2. Carrizo Moreira, A., & Campos Silva Pais, G. (2011). Single minute exchange of die: a
case study implementation. Journal of technology management & innovation, 6(1), 129146.
3. Baudin, M. (2014). Formula 1 Pit Stops, available at:
http://michelbaudin.com/2014/05/01/formula-1-pit-stop-1950-to-2013/
4. Mossman, A. (2013). Last Planner: 5+ 1 crucial & collaborative conversations for
predictable design & construction delivery. The Change Business Ltd., UK, 26.
5. Dave, Y., & Sohani, N. (2012). Single Minute Exchange of Dies: Literature Review.
International Journal of Lean Thinking, 3(2), 28-37.
6. Ulutas, B. (2011). An application of SMED Methodology. World academy of science,
engineering and technology, 79, 101.
7. http://setupreductiononline.com/smed-seperating-external-and-internal-activities/
8. Jones, K. & Derrick, J. (2015). A Chamber Installations Process Improvement M60 J8
& M62 J19. Lean Construction Institute-UK Yearly Summit Presentation, Birmingham,
UK.
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