Single Piece Flow (SPF) supports Just-in-Time, Toyota Production Systems, Lean Manufacturing and similar types of philosophies and systems.
In a true one-piece flow, each operation only builds what the next operation needs. If the next operation gets backed up for some reason, then preceding operations actually stop. It seems that nothing can be more uncomfortable in a traditional manufacturing operation than stopping. Yet the alternative to stopping is overproducing—producing more, sooner, or in greater quantity than the next operation requires.
Toyota considers overproduction to be the worst of the seven types of waste because it leads to the other six types of waste (inventory, movement, handling, hidden defects, etc.). This is the key to understanding how less can be more (less means fewer parts produced in some individual steps in the process, more means getting more value-added activity done from the overall process). The case example below explains a typical situation of overproduction that reduced the ability to meet the customer requirement.
