The Supermarket is the Customer
When an organization is focused on implementing lean, one of the first things that everyone talks about is focusing on the customer. It could be the external customer or the internal customer.
Who the external customer is seems to be clear in most cases. But when dealing with internal customers it isn’t always as straight forward. In my experiences, the person says their internal customer is the next physical process that changes the product (or service).
What if you have implemented a pull system with a supermarket in between two physical processes?
The functioning of a supermarket is a process. Product enters, waits, and then exits to the next physical process. The product does not physically change, but the supermarket is a process.
Even in lean notation we over look this. If you are familiar with Value Stream Mapping, the is a specific inventory icon for a supermarket. It does not get notated with a process box.
Now if the mindset is the supermarket is a process, then it is the customer of the physical process upstream and the supplier of the physical process downstream.
This changes how questions are asked around creating a pull system. Instead of asking, “How much does process 2 produce? Or what is does process 2 need?” , the questions should be, “How much leaves the supermarket in X timeframe? When does the supermarket tell me to produce?”