Kanban is a Japanese term referring to sign board or visual signals that authorize the production or movement of items in manufacturing environment. A Kanban system is a self-regulating pull system that leads to shorter lead times and reduced inventory. Kanban systems are typically applied to items that have relatively constant demand and medium-to-high production volume.
It works on the basis that each process on a production line pulls just the number and type of components the process requires, at just the right time.
Kanban system is similar to the human body control system as instructions send by brain to body parts, a kanban system gives instructions for control of production to every work area in a lean production system. It connects information flow with the material flow by attaching kanban cards to the actual goods.
A kanban is a card with an inventory number which is attached to a part and before installation, the kanban card is detached and sent up the supply chain as a request for another part. A part is only manufactured (or ordered) if there is a kanban card for it. Few generally accepted rules are
- Downstream processes may withdraw items in the amounts specified on the kanban card.
- Upstream processes may send items downstream as per quantity and sequence as per kanban.
- No items are made or moved without a kanban.
- A kanban must accompany each item at all times.
- Defects and incorrect amounts are never sent to the next downstream process.
- The number of kanbans should be monitored carefully to reveal problems and opportunities for improvement.
Kanban employs Kanban card wherein, Kan means color and Ban means card used for inventory.
Kanban starts with the customer’s order and follows production downstream. Because all requests for parts are pulled from the order, kanban is sometimes referred to as a “pull” system. Kanbans represent replenishment signals that are usually manual and highly visible such as a color-coded card that moves with the material, a light that goes on when replenishment is required, or an empty bin that is moved to the supply location to trigger replenishment.
Kanban Principles
Kanban is an approach to process change for organizations which uses visualization with a kanban board, allowing a better understanding of work and workflow. It advises limiting work in progress, which reduces waste from multitasking and context switching, exposes operational problems and stimulates collaboration to improve the system.
Kanban focuses on the customer and work which meets their needs, rather than individuals’ activities. Kanban has six general practices: visualization, limiting work in progress, flow management, making policies explicit, using feedback loops, and collaborative or experimental evolution. They involve seeing the work and its process and improving the process, keeping and amplifying useful changes and learning from, reversing and dampening the ineffective.
Kanban Boards
Although Kanban does not require that the team or organization use a Kanban board, it is the preferred way to see the flow of work, get the participation of the team, and manage work.
Kanban Metrics
Kanban team choose metrics that help them move forward, not to finger-point or penalize someone. Some commonly used metrics include:
- Task Completion Rate (TCR) – Tasks completed per day
- Task Add Rate (TAR) – Tasks added or arrived per day. If TAR exceeds TCR, then the team has a continuous flow, the queue is never exhausted and the project is never completed
- Current Task Estimate (CTE) – Total number of active and pending tasks (i.e. represents remaining work)
- Days to complete = CTE / (TCR – TAR)
