What is One Piece Flow?
August 1, 2005
By Darren Dolcemascolo
One-Piece flow is one of the most important principles of lean manufacturing. Yet, many people still do not understand what it truly means to achieve one-piece flow. Let us begin by discussing terminology. There are several basic terms used to describe one-piece flow. The most common are as follows:
Each of the above terms describes the same key element of the Toyota Production System, illustrated in the diagram below. As you can see, "Flow" is a shown as a key element of the pillar, "Just-in-Time."

Thus, one-piece flow is a tool that will help a manufacturer achieve true just-in-time manufacturing. That is, the right parts can be made in the right quantity at the right time. In the simplest of terms, one-piece flow means that parts are moved through operations from step-to-step with no 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 usually U-shaped cell in the sequence in which it is used. To achieve true one-piece flow, equipment must have basic stability:
One-piece flow is usually associated with low-mix, high-volume manufacturing environments. However, one-piece flow also lends itself to high-mix, low-volume environments. It is usually achieved by creating mixed model or group technology cells, in which a number of products run through a particular cell utilizing one-piece flow. Although every organization has unique challenges, one-piece flow can be achieved through proper application of the principle.
Click here to subscribe to our free e-newsletter Learning to Lean and receive three articles like this one each month.