What is a value stream map?
A Value stream map is a flow chart which uses symbols to show and improve the flow of inventory and information round the process.
A value stream is all actions required to take a process from raw material at the supplier all the way to the finished goods at the customer (or for other processes the entire process from start to finish. It shows all the steps, whether value creating or not, which take place in your operation.
It is best to include as much as possible on your map, as even external items e.g. methods of shipping to your factory can show up issues. It is best to have the full process from customer deciding they want your product up to them receiving it. You can however do a value stream map of a small part of your operation, to give more detail on a process.
What is the purpose of a value stream map?
Creating a value stream map is the best way to remove the seven wastes that are the key enemy in Lean:
- Transportation – Excessive movement of goods or people between processes
- Inventory – Storing more stock than is necessary for the efficient running of the business
- Motion – Excessive movement of goods or people within a process (including reaching for things)
- Waiting – People or product that have to wait for the next stage in a process, increasing costs
- Overproduction – Creating more finished product than is needed
- Overprocessing – Effort put into a product that isn’t valued by a customer
- Defects – The cost of poor quality. The wasted time, product and resources in detecting, fixing or disposing of defective product
The value stream map very quickly shows in a visual way how the process operates and let you quickly zoom in on the waste.
Value stream maps as a process improvement
Value stream maps can be used on their own as a process improvement method, for reducing waste:
- Identify the process which you want to map and improve
- Draw a map of the current process
- Time each part of the process and add to the map (don’t rely on ‘standard times’)
- Analyze the current process for waste or potential improvements
- Draw up a future state value stream map
- Implement the improved state
- Measure the new system to verify improvements
The steps can be repeated to build upon previous gains to get an even better solution, which may have not been obvious from the original method.
VALUE MAP SYMBOLS
Customer / Supplier Icon – Value stream maps go from left to right, so the supplier in the top left corner of the map and the customer in the top right corner should both use this symbol
Process Icon – an operation that occurs in the operation – can be e.g. an assembly or department, or an individual process within a department
Shipment Icon – used for external movement (usually from suppliers or to customers)