SMED Explanation

SMED

Shigeo Shingo

SMED is an acronym for Single Minute Exchange of Die. Now a days, this is a widely used phrase, common across all manufacturing industries. "Single Minute" does not imply that the changeovers need to happen in just 1 minute, but that it should be completed in less than 10 minutes (Single digit minute). SMED concept basically advocates rapid set-up changeovers. It is one of the many lean manufacturing methods, reducing waste in manufacturing process. 

History and background: 

The origins of SMED can be traced back in the past 1950s in Japan. The concept initially was demonstrated by Shingeo Shingo during the inception days of Toyota Production system, to reduce the setup time of the molding process associated to car body.

Henri Foard

Similar lean practices were also observed at Ford Motor Company in earlier 1920s to reduce the manufacturing cost of Model T vehicle. One of the great example being, the multiple drills for the engine block, which included dozens of drill bits of different sizes. At Ford Motor Company, they improved the process of multiple pass to single pass operation for all required holes at specific orientation.

Alfred P. Sloan

In the year 1930, General Motor Works Company, along with Alfred P. Sloan brought the concepts of rapid Change Overs in order to be able to bring New Models every year. At that time only General Motors managed to bring down their model changeover time to be around 20 days compared to 6 months of Ford Motor Company.

However, many researchers from United States of America were also working on different aspects of lean and drastic reduction of Changeover time. Probably the most prominent names in this era were motion expert Frank Gilbreth and the father of scientific management, Winslow Taylor. Gilbreth studied and improved working processes in many different industries, from bricklaying to surgery. As part of his work, he also looked into changeovers. His book Motion Study (also from 1911) described approaches to reduce setup time. He gave birth to the concept of THERBLIG, which are 18 kinds of elemental motions used in the study of motion economy in the workplace. Taylor analyzed non-value-adding parts of setups in his book, Shop Management, written in 1911 and his studies were widely excepted and removal NVA ( Non Value Added) activities were well taken in lean practices.

Fig 1. A Brief History – a schematic diagram depicting the maturation of lean practices

Concept Explanation:

During Setups, there are activities that can be performed while the process is still running. These activities are termed as External Activities. At the same time during setups there are some activities which can only be performed when the process is completely stopped. These activities are termed as Internal Activities. SMED focuses on making the work elements external as many as possible and then simplifying and stream lining all other work elements.

Before understanding the concept of SMED we need to understand what is change over and thereby we need to understand change over time.

·         Changeover Time: In most of the manufacturing factories where same set of machines are used to produce products or components of different specifications, they face issues of down time due to machine stoppage during changeovers. These are the stoppages, consciously taken for preparing the machine to swap from one component to another component. These setup changeovers are non-value added activities, as explained in the following Diagram.

Fig2.: Explanation of Changeover time and Non Value added activity

• ·         Elements of changeover :

Now as we have understood the concept of Setup or changeover, we need to understand and measure the elements of Setup. Measurement of work elements in terms of time is very important, because we can’t improve something that we can’t measure. Anyway, below is a tentative structure of elements of setup converted into a pie chart of percentage contribution of each type of work element. 

                                                   Fig 3. Explanation of Elements of Changeover 

• ·         Benefits of SMED :As we have understood the concept of SMED and thereby, have known some of the aspects of changeover, so before getting into the steps of implementing SMED, I would like to give a critical overview of the benefits of SMED implementation.

#	Target Matrices	Means or Measures	Benefits in the form of Out Comes
1	Increased Capacity	Reduced changeover time	Production capacity enhancement
2	Reduced manufacturing cost	Faster changeover means less equipment down time	Increased machine availability
3	Smaller lot sizes	More frequent product changeovers	More product portfolios can be addressed through same manufacturing setup
4	Improved responsiveness towards customer expectations	More flexibility is available for scheduling	More variants can be adjusted to  fulfill customers’ expectations in the same production line
5	Lower inventory levels	Demand of smaller lot size in the production process with increased variants	Lower inventory levels due to smaller lot sizes which makes it more easy to manage
6	Smoothening Startup	Standardized changeover process is built	Improved consistency and quality due to focused improvements

·         SMED Implementation Process :

The typical SMED implementation plan covers the following 7 steps as detailed below; and most often the lion’s share of all gains are made from the following first 5 steps :

1.       Separate the internal from external setup activities

2.       Standardize external setup activities

3.       Convert internal setup activities to external setup activities

4.       Improve internal changeover tasks

5.       Improve external setup tasks

6.       Mechanizing the setup or using automation

7.       Complete elimination of changeover ( Ideal Situation)

In my next blog I will explain the 7 steps with illustrative examples. Thanks for reading…! Hope this will help and add value.

Next Blog : Implementing SMED : https://kalpanathchatterjee.blogspot.com/2019/03/implementing-smed.html