December 1, 2003
By Darren Dolcemascolo
A current state value stream map will enable you to see the complete door-to-door flow in your facility and to identify and prioritize areas for improvement. Before you create a current state map, you should have already identified the value stream you want to analyze. You will need the a pencil and paper (or laptop) and a stopwatch for obtaining time samples.
Below is a list of the information you will be collecting at each process step:
1. C/T Cycle Time – how often a part is completed by a process. Use a stopwatch if necessary. (In some cases, machines will give you this information). Be sure to separate machine time from operator time.
2. C/O Changeover time – the time required to switch from producing one product type to another type.
3. Uptime – the percentage of time in which a machine or process is available on demand.
4. EPEI (production batch sizes) - the batch size expressed in time (days, etc.). EPE stands for “every part every _____.”
5. Number of operators
6. Number of product variations
7. Pack Size – the number of items in a shipment
8. Working Time (minus breaks)
9. Scrap Rate
Begin with the customer’s requirements. Draw the outside source symbol to indicate the customer’s location to which your product ultimately goes. Draw a data box and record the customer requirements (units required/month, pack size, etc.). There may be multiple customers. Next, continue working backwards with the step just before product arrives at the customer, the shipping method. Again, using the appropriate icon, note how frequently product is shipped to your customer(s).
Next, go to your shipping process and draw a process box for shipping. Collect any of the relevant process data and enter it in a data box. Before the shipping operation, draw an inventory icon and indicate how much inventory is waiting for shipment.
You are now ready to analyze the production processes. In door-to-door value stream mapping, you do not necessarily need to map each process step. The process box should indicate one area of material flow. The process box stops wherever processes are disconnected and material flow stops. Note that there may be some (not very significant) WIP inventory between processing steps within an area of material flow, but you should still use one processing box. (NOTE: In door-to-door Value Stream Mapping, if there are distinctly different process steps with WIP in between and transfer between steps in batches, then each step gets its own process box.)
Working backwards, create process boxes for each area of material flow. Collect and note all appropriate process data, and show inventory in between process boxes. The last step in the product flow portion of a current state value stream map is to show the transportation of incoming materials and the supplier(s), again using the outside source symbol.
After the physical product flow portion is complete, you need to create the information flow portion of the current state value stream map. This portion is drawn above the physical flow, and it generally begins with the customer’s requirements again. Using process boxes and information boxes, map the information flow from the customer’s requirements back to your supplier(s). For example, your customer gives you a monthly forecast (information box), which is fed into your production control system (process box). The production control system creates a forecast for raw materials that you give to your suppliers.
Lastly, you must tie in your information to your physical product flow. For each physical process step, ask each operator how he/she knows what to work on next. This is a key question that will reveal how effective the information flow is. Draw an arrow from the information flow item that answers this question to the physical flow process box. For example, if there is an assembly operation that is based on a weekly schedule, draw a line with an arrow from the weekly schedule to the assembly process box. Then ask the question, "where does the weekly schedule come from?" The answer is typically production control. Another example is your shipping process. Your shipping process might be based on sales orders entered into your system; draw a line from your sales order system to your shipping process box. After you've done this for all of your physical processes, your current state value stream map is complete.
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