Value Stream Mapping is a lean tool that uses a flow diagram and documents in high detail for every process step. Value Stream Maps highlight processing time, wait time, and material handling. The maps are extremely valuable in lean to identify waste, reduce process cycle times, and implement process improvement.
Similar to a process map, Value Stream Mapping is most beneficial in team setting, as many of the issues it highlight goes across departments and responsibilities. By having representatives from the different departments, also give a better common understanding of the process and problems.
Current State Value Stream Mapping
Start with a present state map of the process as it currently is, this give a better understanding of the process, as well as identify where the problem or opportunities are.
At this point we are not interested in how the process are supposed to work or designed to work. We want to see how the process is actually working today, and capture it in a current state value stream map.
Initially Value Stream Maps can seem a bit messy and confusing, but with a little training or self-study, it quickly becomes much clearer.
Creating the Value Stream Map
When doing the current state Value Stream Map, start with calculating the takt time. It is defined by available work per shift divided by the demand of burgers per shift.
As an example we can use a burger factory with a daily demand of 1200 burgers, and the working hours as follows.
- Hours per shift: 8
- Break minutes per shift: 30
- Shifts per day: 2
- Days per week: 7
This will give our factory a tact time of 45 seconds, meaning we have to produce a burger every 45 seconds.
When creating the value stream map, it is best created by hand using a pencil (frequent corrections and changes are needed). Use a sheet of A3 paper to have enough space for everything.
VSM’s can be created by software which is beneficial when presenting it to management, but as a starting point you are better off to create by hand and involve the entire team in its creation, and then use the software when it is finished and ready to be presented.
VSM Step One – What to Map
Start with deciding exactly what you wish to map. I our example it is easy as we only have one product which is a burger, but for most businesses it is a bit more complex than that. In that case a Pareto Analysis of your products can be used to decide which one to start with, based on e.g. volume or cost.
VSM Step Two – The Symbols
Below is an example of some commonly used symbols that can be used for Value Stream Mapping, but it is not necessary to use those if you have some other symbol for your processes that you already use.
VSM Step Three – Bound the Process
Set the limits for your map, you need to determine the scope or how much of the process that will be covered. Often the VSM is conducted from the Supplier through to the costumer, which them becomes your first and last box in your map.
VSM Step Four – Define Process Steps
Once the boundaries are set, all the process steps need to be defined. This is done by walking through the process either from start to end or from end to beginning. Different people have different preferences in terms of how they prefer to do it, the way to do it is not that important as long as the entire process get mapped.
VSM Step Five – Add Information Flow
Adding information flow to the map is something that is unique to VSM compared to most other mapping tools.
The things that need to be captured are how costumers order products, how often and how they do it. Also it needs to be included how this translates back into supplier.
VSM Step Six – Collect Data
This can sometimes be a bit of work, so some planning as to using the team for data collection and how to collect the data is usually beneficial.
Typical types of data collected are.
- Cycle time (time to make one product)
- Change over time (from finishing starting on next piece)
- Uptime (machine utilization on demand)
- Number of operators
- Shifts worked
- Net available working time
- Scrap rate
- Pack size/pallet sizes
- Batch Size
VSM Step Seven – Interpreting the Map
The Value Stream Map now contain a lot of information about your process on one single piece of paper, making it easy to see where there are problems or opportunities for improvement within the process.
VSM Step Eight – Ideal or Future State Map
Once all the problems have been defined they can be tackled one by one, but more important is what the ideal state of your process is. It could involve implementation of Kanban System or many other items for improving the process.
When the ideal state have been reviewed and approved, an action plan can be made working towards the goal. Kaizen Events can be used for improvements you want to make, e.g. reduce the time for a tool change from 40 min to 10 min.
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