So far, we have a process map with boxes and arrows. There is one more symbol I should have mentioned: triangles. We use triangles as the symbol for inventory. Any place in the process where stuff sits, put a triangle there.
For example, raw materials come from the supplier and get put in a warehouse…put a triangle there and label it “Warehouse”. If raw materials get taken from the warehouse and are staged in front of an operation…put a triangle there, too. Work in process between stages…put triangles there. Finished goods get a triangle.
How about if material gets put somewhere right after a process step, then is taken and put somewhere else right before the following process step? That does mean we put two triangles between the process steps? How about if the material gets put somewhere after the process step, gets moved to a storage area, then gets moved to a place in front of the next process step? Would we insert three triangles in that case? Yes and yes. Because we want to see every place that material or work in process is sitting for any length of time.
So…boxes for process steps, arrows for movement and transportation, and triangles for “stuff sitting and waiting to be moved or for something to happen”.