Kanban - A system that ensures the required parts are received when they are needed in the volumes they are needed.

At the end of this Kanban instructional journey are the Black Belts of Kanban, the Toyota plant and one of its primary suppliers, Toyota Boschoku. Toyota Boschoku started in 1914 as a spinning and weaving company. The production line of the Toyota Tsutsumi plant (making the Camry and Prius) communicates to the Boschoku via e-Kanban in a continuous fashion during the working day. This kanban notification to Bobuschoku set their paper Kanbans into motion. Boschoku is the supermarket for the Car assembly line and they have various production lines within their factory.

Boshoku make 610,000 pieces monthly, for 23 different customers. Boschoku has 180 inventory turns per year. This means that they deplete and replenish their inventory every 18 hours. In order to do this they must be completely in sync with their customers demand on a moment by moment basis. Kanban helps them make this connection. Each day they handle 20,000 kanbans.

One application of the kanban was in support of one of the assembly cells. This was a one person work cell. A kanban card was swiped by the operator and the materials were provided to him. The materials were perfectly positioned for his work and included the standard work instruction for the piece he was assembling, appearing on a monitor directly in front of him. To his right the correct tool tray was automatically unlocked for use to make sure he had the right tools (poke-yoke).

The plant has all the lean elements to perform significant manufacturing. They focused on flow, die turnover and making sure that they meet customer demand. A strange similarity is that the Toyota Boschoku plant building has a serrated roof line that looks exactly like the symbol for “supplier” in our Value Stream Maps.

The main event was shown in the Toyota Tsutsumi plant. Receiving shipments every hour during the workday, they quickly use and refill the 30,000 parts required to build a Prius or Camry. They build 34,000 cars per month at the plant in two shifts. The goal for the line we observed was 288 cars. They were running at 97% of this goal as we observed the process in the afternoon. The takt time for the line has a car finishing every 3.3 minutes. Their lead time is 20 hours.

Dollies holding parts and tools accompanied the body down the line. Just like in the one-person cell each station had an instruction sheet for the particular car at the station. Kanbans were so integrated in the flow of materials that it was hard to see any differentiation between the kanban and the arrival of the materials.

One place where they did not use kanban cards was in final door installation. Each door was perfectly matched to the main vehicle body. The doors were removed after painting to allow improved access for installation and to avoid cosmetic damages. The removed doors continued along at exactly the same rate as the body and they arrived in the precise order needed at exactly the right time. The kanbans are unnecessary.

Tomorrow we will be discussing lessons learned and steps for Kanban at Children’s