Lean Line Design Line Requirements Part II
Now that you have have your Takt time and your Value Stream Maps the next step is to create your station map. The first step is to figure out how many stations you need. This is done by taking your total time in your future state map and dived it by 40% of the takt time. Each station should be around 40% of your takt time for any particular value stream. The 40% allows for flexibility and you will have more stations than people. This allows for flexing production up and down based on volume. You can use another number besides 40% but 40% tends to work well for most cases. If your total time to build a unit is greater than takt time then use the calculation we just mentioned. If it is less than or equal to takt then you have freedom to choose how you want to break apart the stations.
Takt < Total Build time for one unit
Number of Stations = Total Build time / (.40 * Takt)
Takt >= Total Build time for one unit
Number of Stations = logical breakdown of tasks
Once you have your initial number of stations then go through and fill them up with tasks. You should have several work elements and should be able fill the stations with work. Try to come as close as you can to 40% of takt for the work content in each station. It won’t be perfect but get as close as you can. Once you have this information then we create cardboard mock-ups to emulate the new designs. You’ll do a dry run going through the motions of your new line in the cardboard mock up. Your mock up doesn’t have to be out of cardboard as shown by the picture below. It is a mock up of a food production process during the weighing and measuring process. The team used this space to run through a new designed process.
Process for Line Requirements
1) Create your value streams
2) Find your takt fro each value stream
3) Take your total work element times and takt to find your number of stations
4) Assign work elements to each station
5) Test the new production line with a mock up