One of the key tenets of Lean Manufacturing or Office Lean is to identify the value stream you are analyzing. A value stream is defined in the APICS Dictionary as “the processes of creating, producing, and delivering a good or service to the market.” A value stream may be internal to a company, or it may include external suppliers in addition to internal processes.
Understanding your value stream is important for two reasons. First, it enables you to group products by the processes that make them. Second, knowing the value stream allows you to focus on a set of linked processes and helps to prevent distraction in your analysis.
To identify a value stream you need to create a matrix that crosses process steps (manufacturing steps) with products. Those products that use the same processes (or have a high percentage of the same process steps) belong in the same value stream. The fact that these products may have different end users, or go to completely different customers, is not relevant. It’s the process steps that define the value stream.
With the value stream identified you can begin the task of mapping this value stream. By walking the value stream on the plant floor, or the office (for Office Lean), and noting the work time (value-added time) and the non-valued -added time you will create a visual map and be able to see areas for improvement.
Remember, the purpose of a value stream map is to identify activities that don’t add value to the end product. By eliminating these activities you will gain a faster through-put, higher level of quality and reduced inventory. These improvements start with the analysis of the value stream and to do that you must first identify this stream.
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