Value Stream Mapping
Value stream mapping is a toolset widely used in lean continuous improvement programmes to help understand and improve the material and information flow within the supply chain. In simple terms Value Stream Mapping is used to capture and present whole processes in a format that is easy to understand by those working the process. Fundamentally value stream maps capture the current process, warts and all, in order to clearly expose waste and other issues within the mapped process.
With a clear picture of the current process a new, future state process can be developed; a team approach is normally adopted to arrive at a future state process. As with other lean management toolsets the principle goal of Value Stream Mapping is to deliver improved processes that meet the needs of the customer more effectively and efficiently.
Value Stream Mapping is used to categorise process activities into three main classes:
- Activities that add value for the customer
- Necessary activities that do not add value for customer
- Activities that do not add value or waste
The Value Stream Map should consider and identify activities in the following areas:
- Material Flow
- Data/ Information Flow
- Inventory and Buffer stock
- Material Handling
- Suppliers, internal and external
- Customers
- IT Systems
Accurate performance measurement data is a key component that can be used to enable the objective assessment of the current state. For example, by applying Pareto’s Rule (roughly 80% of the effects come from 20% of the causes) to, say, the causes of downtime at a machine the continuous improvement team can, at first, focus suggested improvements that deliver the greatest reduction in unplanned downtime.
On the face of it Value stream mapping is not complicated but unless some consideration is given to presenting the maps in a consistent style they may be confusing and difficult to understand. Principal to lean is the delivery of value to the customer in the minimum number of steps and with minimum waste; applying this principle to Value Stream Mapping of the current state it is often suggested that the core value adding steps of the process should be presented in a linear flow across the diagram with the non-value adding steps as vertical branches; such a presentation of the process can make it very easy for all to see the waste.