Kanban is a common, everyday word in Japan. It basically means "signboard" or "billboard." In the field of manufacturing, Kanban is primarily a signal system used in production. As material is consumed, a signal is sent to pull and deliver a new consignment. The system is designed so that each process in the production line pulls the right number and type of components the process requires at the right time.
In the words of Taiichi Ohno, the man who conceived the art of Just-in-Time (JIT), Kanban is a tool for achieving JIT.
The Origin of Kanban
Toyota was one of the first companies to apply the logic of Kanban systematically and successfully. In the late 1940s, the company was struggling to find ways to improve its plant production, and it found the U.S. model for supermarkets interesting. In a supermarket, the customer gets the right amount of the right thing at the right time. The store stocks only what it is sure to sell, and the customer takes what he or she desires. By monitoring and maintaining the flow of materials, Kanban achieves precision in production. In 1953, Toyota adopted this market concept at its manufacturing plants.
The Basic Rules of Kanban
- Rule 1: Use a Kanban signal only when the part it represents is consumed.
- Rule 2: Do not withdraw a part without a Kanban.
- Rule 3: Issue exactly the same number of parts to the subsequent process as specified by the Kanban.
- Rule 4: Never issue defective parts to the subsequent process.
- Rule 5: The preceding process should manufacture exact quantities of parts withdrawn by the subsequent process.
- Rule 6: Manufacture the parts in the order in which the Kanban cards arrive.
- Rule 7: Stop the process if the production requirement decreases, and use overtime and production improvements to handle requirement increases.
Types of Kanban
There are two types of Kanban: Transport Kanban and Production Kanban. The information given on the card is what differentiates the two systems. The Transport Kanban card informs the recipient of the origin and destination of the part/component. The Production Kanban card outlines the details of the operations that need to be carried out by a specific workstation on the production line.
The Benefits of Kanban
- It is simple and efficient.
- It provides exact information quickly.
- The transfer of information does not cost much.
- It reduces the quantity of work in progress and the stock of finished goods.
- It makes it easy to notice and rectify problems instantaneously.
- It responds quickly to changes.
- It helps to prevent overproduction.
- It limits waste.
- It makes delegation easier.
- It achieves decentralization of responsibility by emphasizing the individual worker's contribution to the production process.