Lean Line Design Line Requirements Part I
In previous posts on Lean Line Designs we introduced terminology and introduced the concept of the current state map and future state map. We are now at the point that we need to determine the line requirements. The first step in determining a Lean Line Requirement is to determine the Value Streams the products fall into. Simply create a grid with the rows representing different product types and columns representing process steps. Simply put an “x” where the product requires a particular process step.
Now you have your Value Stream maps. In the example above you have four products but essentially would have two value streams. This means that you will probably need two separate “lines” in your facility to address each value stream. Some facilities have as few as 1 and can have multiple value streams. Once you know this then the next step is to calculate your takt time. Takt is the required run rate to meet customer demand. An easy way to do this is to create a simple forecast based off of the last year’s volumes and build in a 10-20% buffer in those numbers. Once you have your total volume in units for each value stream then you need to use this formula:
Total Time Available for Production [seconds/year] / Total Volume [units/year]
Where total time available for production are the total number of seconds you have available to work minus breaks. You will get a number that will tell you how many seconds you have to build a single unit. This is your takt time.