Last Updated on 13 September 2023
A Value stream map is a flow chart which uses symbols to show and improve the flow of inventory and information round the process. To understand Value Stream Maps, we first have to understand a couple of concepts that make it up; value and the value stream.
What is Value?
In essence, value is what you do that the customer is willing to pay for. Waste is anything that you do the customer isn’t willing to pay for. It is a key concept in lean as what the organization considers to be value added may not be the same as what your customer does. Where there is a mismatch, you may be creating waste where you think you’re creating value.
What is the Value Stream?
The 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.
Each process in the value stream is the points where the value is added by your organization to the product. To map the whole value stream is to map all the points from when the customer notices they have a need all the way to when all activity on that request has ended. This can include office tasks such as invoicing and payment.
What is a Value Stream Map?
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 map of a small part of your operation, to give more detail on a process.
When do you use a VSM?
This is a very powerful process mapping tool, so many experts like to make a VSM every time they do a Lean or Six Sigma DMAIC project, and they have an impact on several of the project stages..
A ‘current state map’ showing how the process currently operates will usually be created at the start of the Measure phase. This will give a lot more information on how the process is running rather than using the procedures which show how it should be operating.
A ‘future state map’ documenting how we would like the value stream to look will be created in the Improve phase of DMAIC. It is a fantastic tool to remap how the flow is going to look for laying out your improvement plan.
This future state map will also be the first draft of the process map when you are documenting the procedures in the Control phase.
What is the purpose of a VSM?
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.
How do you make a Value Stream Map?
There are many steps to making a a value stream map, of which a quick summary is:
• Create the current state map
• Create the future state map
• Make an action plan to get from the current state to the future state
Current state map
Step by step guide to making a VSM current state map:
Map the processes
Place the supplier in the top left corner of your page and your customer in the top right. Then add the processes through the middle. Essentially you’re creating a flow chart, with the processes going from left to right on the page.
At no point can your flow go back on itself, so you’ll want to plan the level of detail you want to add. You can always create extra value stream maps later that ‘zoom in’ on a section to give more detail. This prevents you from adding so much information as to make it difficult to read.
Add the product flows
Add arrow that show the product flowing through your process from the supplier, through the processes to the customer. If there are jobs waiting at one of the processes when you are measuring, add the inventory symbol and note the number of items waiting to be produced.
Add the information flows
Any communication between departments, from production control, to and from customers/suppliers etc all need to be noted on the the map with information flow arrows. Add the frequency as a note next to them.
Time the steps and add metrics to the chart
You will need to go out into your gemba to actually measure the processes. The speed your processes need to be worked at to meet demand (takt time) write under the customer. You then add the other metrics on the processes they relate to.
Cycle and Lead time go on the timeline at the bottom, and their totals go at the right hand side of the line.
Measure the distances and add those to the chart
It’s usually useful to measure the distances traveled between processes and during the processes, as this is often a good source of efficiencies. Either add these to the data boxes below the processes, or to a separate ‘distance line’ below the timeline.
Future state map
You can start from the current state map if the changes are subtle, or start from a blank sheet of paper if more drastic changes are needed. Essentially you follow the same process as the current state map, except that instead of drawing your procedure how it is, you draw how you would like the process to look after your process improvement has been completed.
Value stream maps as 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.
For more information on Value Stream Maps, please look at our sister site, which goes through them in more detail.