Value stream mapping (VSM) is a lean manufacturing tool that seeks to map your process from supplier to customer, highlighting the flows of product and information and identifying delays and non-value adding processes.
It is a top level view of your company rather than a detailed look at an individual process within it, but this map is a real eye opener for top management. This is one of the most powerful and yet easy to use mapping tools at your disposal and can lead to a rapid and significant improvement to your business if action is taken following the mapping exercise.
VSM is not just about creating one map; it is about discovering where we are today with a current value stream map and using the team to create an ideal state value stream map as a target to aim for whilst creating a series of future state maps to work towards on the journey to our ideal state.
Why do we need VSM
Value Stream Map
We need value stream mapping to create a common vision and direction for our company, a current state map created by those involved in the processes creates buy in and understanding as to where we are. The creation of an ideal state together provides that shared vision that all can buy into and work towards.
The creation of future state maps and related action plans help to generate improvements and change within the company worked on by all.
With Lean we are trying to compress the time from order receipt through to the cash arriving in our bank account, This best done through an evaluation of the value stream as a whole, not just concentrating on the small period of our lead time taken up by manufacture.
What do we Map?
Value stream mapping is usually conducted on a single product or family of products from supplier through to customer. Where we have multiple products it is tempting to try to map them all but this would just result in information overload.
The team should choose one product or family on which to create the map, any improvements made on this value stream can then be used as a template to improve other value streams. At times it is difficult to find product families if you have a large number of individual products. Product family analysis is a useful tool to use to find the similarities between products to allow the creation of families.
How do we VSM
Value stream mapping is a team process that should take place at the gemba (the workplace), not within an office by an expert using data from written procedures about what should happen. Your value stream map should reflect exactly what does happen along with real current data regarding stock levels, delays, change over times, quality levels and so forth. It is this map that will form the basis for your improvements.
Ideal and Future state Value stream maps
Once you have your agreed version of your current state map it is time to move directly onto creating your ideal and future state maps.
The ideal state value stream map requires a firm understanding of lean manufacturing principles to enable the team to visualize an ideal lean process. This would often be a single dedicated cell controlled through a pull kanban system rather than a grouping of shared processes each scheduled from an MRP system pushing product onto the next process, with daily or even hourly deliveries to customer and from supplier. The ultimate ideal of course being single piece flow at the demand of the customer (JIT).
Often it is impossible to jump straight from the current state to the ideal so the team needs to agree a future state map to work towards on the journey to the ideal state. This then becomes the basis for an action plan; you may wish to first work at standardizing and improving processes to improve cycle times and reduce defects or whatever the most pressing issue is for your business highlighted on your VSM.