One Piece Flow
One Piece Flow is a fundamental element of becoming lean. To think of processing one unit at a time usually sends a shudder through the organisation which has batch manufacturing as its life blood. The word “one” does not necessarily have a literal meaning. It should be related to the customers’ requirements and could be one unit of order. However, what it does mean is that the organisation should only process what the customer wants, in the quantity he wants and when he wants it.
At this point we can start to take large amounts of waste (muda) out of the organisation because it is a journey without end. However, it is not without pain and a lot of problem solving.
Sometimes referred to as “single-piece flow” or “continuous flow,” one-piece flow is a key concept within the Toyota Production System. Achieving one-piece flow helps manufacturers achieve true just-in-time manufacturing. That is, the right parts can be made available when they are needed in the quantity they are needed. In the simplest of terms, one-piece flow means that parts are moved through operations from step to step with no work-in-process (WIP) in between either one piece at a time or a small batch at a time. This system works best in combination with a cellular layout in which all necessary equipment is located within a cell in the sequence in which it is used.
While many are familiar with the terminology, there is still a significant amount of confusion regarding what one-piece flow means and, more importantly, how to achieve it.