This signal triggers the movement of material from one operation (or store) to the next down-stream operation.
The retrieval quantity can be different from the Production quantity, and the process usually starts with the use of parts (shown as Op 1 in Figure 7 – parts removed and parts retrieval to operator). This signals a material handler to move a full container from Op 1 to Op 2.
Op 2 shows the movement of Kanban from conveyor to proceeding operation. This then signals to the feed operation (Op 3) to begin production to fill container.
Op 3 once complete, material handler removes production Kanban and adds retrieval Kanban.
Op 4 these are transported to conveyor and cycle begins again.
Figure 7 illustrates the system perfected by Toyota. Within the diagram we can see a 2-card Kanban being operated, with the production instruction Kanban and the parts retrieval Kanban.
Figure 7: Conceptual Diagram of the Kanban System (source: www.toyota-global.com)