What do changing wheels in a few seconds in Formula 1 and preparing the Hikari Shinkanzen high-speed train in Tokyo for its next run have in common?
SMED is one of the tools of lean and stands for „Single Minute Exchange of Dies“ and is a method that reduces the time it takes to change a tool to less than 10 minutes
Why do we use SMED?
- Our customers want several different products in exactly the quantities they need.
- They want to get these products in high quality, at low prices and with fast delivery.
- SMED helps us to meet these requirements.
- If we want to have fewer changeovers due to long changeover times, we need to increase our batch sizes.
- If we increase batch sizes, inventory levels will increase.
- If we increase inventory levels, the amount of waste will increase.
- If the volume of waste increases, costs will increase disproportionally.
And the smaller the batch size:
- The smaller the inventory levels.
- The higher the flexibility.
- The shorter the lead times.
- The lower the costs -> So the ideal is to produce small batches -> therefore we need to be able to do quick changeovers.
But how to do it? Analyze the actual tool changeovers. Either record it or observe and record the activities and measure the times.
Step 1: Separate internal and external activities.
– Internal activities that can only be performed when the machine is off – e.g., tool removal, tool insertion,…) Formula time in pitstop.
– External activities (activities that can be performed while the machine is still running or running again – e.g. transporting a new tool to the machine or to a storage location,…). Preparation of everything needed in advance, mechanics exactly at their positions before the pilot in the formula drives up to them.
Step 2: Convert internal activities to external activities – everything that can be done. Preparing all mechanics with tools at pitstop, original wheels only taken away when the formula is gone.
Step 3: Simplify remaining activities. Divide tasks among team members, provide appropriate tools to speed up work (screwdrivers, jack).
Step 4: Continuous improvement- establish a clear process of who should do what and when- constantly practice and test – F1 mechanics have certainly done hundreds and thousands of pitstop tests.
Oh, and the train preparation at the pit stop? It all took about 10 seconds. After stopping at the station, there was a cleaner at each door, and because the train was clean (everywhere was incredibly clean in Tokyo in general), she just turned all the rows of seats 180 degrees in the opposite direction. The train lights then switched from tail to front and vice versa and the train was ready to leave.
Pure fantasy.