Thursday, February 8, 2007

An introduction to the Kanban system

The Kanban system is a powerful manufacturing process which adds flexibility to a manufacturing company. This system has been pioneered by Toyota. Kanban is a Japanese word which means "signboard", or "sign"[1].

The most common method used to explain the Kanban system is to make an analogy with a supermarket. Imagine that you have a supermarket where all of the items for sale have a tag attached to them with detailed descriptions of the item. After the customer has finished shopping and is at the checkout-counter, all of the tags are removed, and forwarded to the purchasing department. The purchasing department purchases replacements for the items and places them on the shelf as quickly as possible.

Within a manufacturing system, the customer is a staff member on the assembly line, the purchasing department is the manufacturing department in charge of providing parts to the assembly staff, the tag is located on the part, and the checkout box is the area where the parts are placed before being taken by assembly staff (each part is stored in a specific location).

In the case of Toyota, the following describes how this process works:
  1. An order is placed for a car (e.g. Camry LE).
  2. A car frame for the ordered car is placed on the conveyor belt.
  3. The belt stops in front of the first assembly worker. This person looks at the order sheet and retrieves the parts required to create the subassembly he is responsible for (i.e. engine parts). The worker assembles the parts and adds the subassembly to the car (e.g. the engine). The Kanban tags for each of the parts used are added to the car and the car moves on to the next stage.
  4. The worker for the next stage proceeds with his own subassembly in the same manner as the one before him did (fetch the components with their tags, assemble the components, add subassembly to car).
  5. The car continues in this manner until all assemblies have been added to it, and the car rolls of the assembly belt.

During this process, the manufacturing department replaces any parts that are used by the assembly staff. In this manner, the manufacturing department only creates parts that have been used.

Relevance to the study of information systems
One of the advantage of the Kanban system is that the IS no longer requires an external Enterprise Resource Planning (ERP) system for inventory management. In the Kanban system, the tags are the ERP system. No other system is needed to monitor the production cycle, since the parts needed to create a car will be requested when needed.

Toyota does use an IS for its manufacturing activities, but it is carefully integrated into its processes[2]. For example, although the IS has enough data to tell an assembly staff member which car model will soon require his attention, this information is not shown to him since it is not required[2]. In other words, Toyota believes that information should be accessed only when it is needed, not "at the earliest possible time"[3] as claimed by the authors of our textbook.

[1] The GRAND CENTURY Japanese-English Dictionary, pp.337, 1982
[2] T.Ohno, Toyota Production System, Productivity, Inc, 1988, pp.27-29.
[3 ] R. Stair and G. Reynolds, Principles of Information Systems, 6th ed., Boston: Thomson Course Technology, 2003, pp. 395.

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