A value stream map is a lean technique used to document, analyze, and improve the flow of information or materials required to produce a product or service for a customer.
> Identify and eliminate waste
> Review the flow of process steps and information from origin to delivery
> Has a system of symbols to depict various work activities and information flows
Value Stream Map extends on the Process Map
A process map is a work that should ideally happen as part of the process on the floor, whereas a value stream map is what actually happens.
- NVA - Non-value-added work - actions that should be eliminated.
- ENVA - Essential non-value-added work - wasteful actions but essential under operating procedures.
- VA - Value Added work - Actions that add value to the work.
- Add time for each activity
- Calculate total time
- Calculate Total value-added time
- VA / Total Time = Process cycle efficiency (PCE)
How to create a VSM?
Example of Pizza Delivery
- Step 1: Identify the start and endpoints
- Step 2: Document the process steps
Next, indicate how many operators complete each step in the circle within each box.
Next, include a data box to indicate:
1. CT or the cycle time - Time to complete each activity
2. CO - Change Over Time The time to switch between steps
3. Up Time - The percentage of time the machine is up and running.
4. Yield - Percentage of parts that pass inspection.
Next, indicate cycle time (CT) (shown in the diagram below).
- Step 3: Add inventory and wait times. Connect the start and endpoints. Electronic flow lines represent customer call and electronic payment, a vertical-lined thick line is material pushed from one process to the other, and the solid thick line is shipment/delivery.
Use Inventory Triangles In between each phase to mark the number of parts in WIP.
Add symbols at the shipment (scooter here) - to show method of shipment
- Step 4: Draw information flow:
- Draw information flow: Suppliers, Production control to represent people centrally coordinating between the suppliers and the pizza store - ensure raw material stock at pizza store doesn't' go below minimum prescribed level.
- Then place lines of communications (straight lines (manual comms) and crooked lines)
- Add notes about the type of exchange, frequency of exchange and the media used
- Step 5: Create Timelines:
- Finally create timelines at the bottom of the value stream map. The timelines will have three levels --
-- Value-added process
-- Essential non-value added process
-- Non-value added process
- Finally, add a databox at the bottom that houses - Total Cycle Time, Value Added Time and Process Cycle Efficiency
Another example of Value Stream Map (Call Centre)
