How to draw a current state value stream map

Why it matters

A current state value stream map is the shared record that explains how the selected product family moves today. The process boxes show where the part changes, the stock marks show where it accumulates, and the information arrows show which decision starts production. While one process runs continuously, the next may wait for material; a mismatch between the accumulated products and the model that is wanted can explain this. Total stock or total production alone is therefore not enough. A map drawn without writing down the product family, the study period and the boundary events gathers different flows into one picture. Even if the calculation looks right, it stays unclear which product experienced which time. The purpose of the map is not to draw the most detailed picture but to be able to explain where the delay arises and which decision feeds it.

To find stock days, you first need to determine the type of question. If the quantity in the queue is divided by the daily demand of the same family, you get how many working days of stock there are based on demand. If it is divided by actual output, you get roughly how long the stock would take to be consumed at that output rate. If the two rates are equal, the numbers come out the same; if they are not, the names and the interpretation of the results are separated as well. In the five-process calculation of this lesson, the common denominator is daily demand. When the flow is assumed to be balanced, this equivalent can be used in a waiting estimate. However, a stock count at a single moment does not prove how many minutes a particular part actually waited. For real waiting, the queue entry and exit events of the part must be tracked separately.

Material flow and information flow must be read on the same product family. If a process gets a daily list in the morning and a verbal priority in the afternoon, both orders are part of the current state. Showing only the official schedule hides why production changed direction. The source of the signal, its receiver, its frequency and the condition under which it changes are recorded. The worker can be asked why they started the last batch; the answer is compared with the observed order. A pull rule that has not yet been implemented has no place on the current map. The solution proposal is kept separate. This way you can see which way of working produced today's queues, and the starting picture is not lost when you compare with the future state.

The time ladder makes it possible to read processing time and waiting side by side in a common unit. A working day is not a calendar day; the working minutes used are written explicitly. If waiting at night, on weekends or outside shifts is being studied, a separate record is needed for calendar time. Not every time seen in a process box is value-added time either. Inspection, rework and transport are classified separately. Here the time scope of the flow is verified first; the value-added ratio in the next lesson rests on this foundation. Finding the longest queue is only a beginning. Setting a goal of simply reducing stock, without verifying how the queue relates to product mix, information delay or insufficient capacity, can move the same delay to another point.

Formula