One Piece Flow
August 1, 2005
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:
One Piece flow
Single Piece Flow
Make One - Move One
Each of the above terms describes the same key element of the Toyota Production System, illustrated in the diagram below. As you can see, "Continuous 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:
Highly capable processes. Processes must be able to consistently produce good product. If there are many quality issues, one-piece flow is impossible.
Highly repeatable processes. Process times must be repeatable as well. If there is much variation, one-piece flow is impossible.
Equipment with very high (near 100%) uptime. Equipment must always be available to run. If equipment within a manufacturing cell is plagued with downtime, one-piece flow will be impossible.
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. To learn more about implementing one-piece flow, click here..
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About the Author
Darren Dolcemascolo is an internationally recognized lecturer, author, and consultant. As Sr. Partner and co-founder of EMS Consulting Group, he specializes in productivity and quality improvement through lean manufacturing. Mr. Dolcemascolo has written the book Improving the Extended Value Stream: Lean for the Entire Supply Chain, published by Productivity Press in 2006. He has also been published in several manufacturing publications and has spoken at such venues as the Lean Management Solutions Conference, Outsourcing World Summit, Biophex, APICS, and ASQ. He has a BS in Industrial Engineering from Columbia University and an MBA with Graduate Honors from San Diego State University.
EMS Consulting Group helps companies implement lean strategies through lean training and lean consulting services. To learn more, read our lean manufacturing case studies or lean manufacturing articles.