Matt Hrivnak

Kaizen: There's always another future state


What is SMED?

If you are like the thousands of people working for a company that is moving towards implementing Lean Manufacturing then I am sure that you’ve heard some very unique terms and acronyms being thrown around.  The most common of these are probably 5S (Five S), Kaizen, J.I.T. (Just-In-Time), Poka-yoke and SMED.

In this post I am going to talk about SMED.  What is SMED?

Well, SMED or S.M.E.D. stands for Single Minute Exchange of Dies.  During the formative years of the Toyota Production System, Shigeo Shingo was determined to reduce the setup time associated with the car body molding process.  (Like many manufacturers, Toyota had traditionally been in the trap associated with Economic Batch Quantities, and originally would produce enough to justify the setup cost).  After some initial trial runs, he was able to create a process that could be incorporated by all operations.  This led to more and more setup reduction events that were eventually cataloged and rolled into SMED.

To fully understand and utilize SMED, one needs to be aware of the entire process related to changeovers and setups.  The classic definition of changeover (from so many sources, over so many years, I don’t know who to give the most credit to, but mostly Womack, Jones or professors of mine from some time ago):  The process of switching from the production of one product to another on a machine by changing parts, dies, etc. measured as the time elapsed between the last GOOD piece of the previous production run and the first GOOD piece from the production run after the changeover.

Notice that the word good is capitalized.  Most people I have worked with and around will, from time to time, negate this fact and try to remove it from the equation.  This is a sin as, depending on the process, adjustments and teardown times can amount to a large portion of a changeover.  Below is the typical breakdown of a changeover/setup by time spent on specific tasks:

Preparing tooling, materials, fixtures, etc.     30%
Adding/removing dies and tools                      5%
Centering/dimensioning tools                          15%
Processing trials and making adjustments    50%

Typically, a SMED is a planned Kaizen event that lasts for several days (usually no more than five) concluding in a presentation to senior management officials.  The team that is compiled to perform a SMED should be associates pulled from all aspects of the company.  For example, one of the SMED’s that I was involved with included the plant manager, two supervisors, two operators from the process (from 1st and 3rd shifts as selected by their supervisors), an operator from another area, a sales/marketing person, and myself, representing engineering and facilitating the event as the team leader.  That number of team members is right around the maximum that you should have working on one event.

The targeted area or type of machine group should be video taped ahead of time by the facilitator of the event.  This is an essential part of the SMED and will be used throughout the process as well as in the final presentation to show the results.

I typically take the first day of the SMED and use it to introduce the team to some of the concepts of Lean and drive home the SMED process and all of its elements.  The most essential part of this training is defining the two aspects of a changeover:  Internal and External setups.

Internal setups are any aspects of a changeover that MUST be completed while the machinery is stopped.  In most cases, these things will be process steps like installing a die, changing gears, flushing/purging a hopper, lubricating interior moving parts, etc.  Notice the keyword in this sentence is MUST (hold that thought for a second).

External setups are just the opposite, anything that MAY be performed or changed while the machine is running.  These are all of the things that should be done prior to the actual changeover and include arranging required raw materials (hopefully from a supermarket or Point-Of-Use (POU) inventory and not a warehouse across town), notifying a material handler to take away the completed product, loading payoffs or racks that feed into the machine, etc. 

As I said before, notice the MUST statement regarding Internal and the MAY statement regarding External.  How often do you think people will do something when you give the option of MAY

A lot of the time, operators will know that these types of things should be done before the machine stops running, but they don’t do them because there is no attention paid to have long it takes them to changeover.  Once it is brought to their attention and made part of the process (everyday) and most importantly, measured, they will start to make much more of an effort.

During the training, I will go over the SMED process with the entire team and answer any questions that each team member might ask.  The process, once understood, is very straight forward.  Actually, like a lot of the practices built into Lean, if you look at changes made during a SMED you should always be able to say to yourself, “Well yeah, that’s what I would have done because that’s common sense; get the materials while the previous job is running, do this and that, etc.” 

While we’re on the subject, the SMED process is as follows:

1) Record current state setup conditions and practices

2) Separate internal and external setups

3) Convert internal setups to external setups

4) Streamline the entire setup process

Now, when I have my team there and have gone through with them, all of the training necessary, we start by watching the actual process.  We always start by taking a walk out to the operation, looking at all aspects of the operation and paying close attention to operator movements, physical space limitations, raw material stores, etc.  After which we return to the SMED team area (usually a dedicated conference room for the week) and watch the entire changeover process that was videotaped earlier in the week.

To be cont’d….

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Comments (3) Posted by matt on Tuesday, March 25th, 2008


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