We frequently hear a lot of lean and tools used but have little to no idea what they mean. The particular tool that I will be drawing will be Kanban. So, what is Kanban? The literal meaning of Kanban means “signboard.” A Kanban system is actually a microsystem of a bigger system which is a Lean system. It is a common tool used to make sure the material gets to the end customer at the right moment (Just-in-Time). It identifies three important things:
- What is needed,
- When it is needed, and
- Quantity required.
Many people trust the Kanban system created by Taiichi Ohno, the godfather of the Toyota Production System (TPS), was solely his concept. That is not totally true. He and his teammates were visiting a grocery store in the US and discovered how they organized inventory and stock control. He soon understood he could follow the same concept not only in the manufacturing process but in any process that has to control inventory and productivity. Oh no look how this would address needless inventory and low levels of productivity and decided to take action.
There is a very well -known saying, “select to use Kanban as a method to drive modifications in your company, and you are subscribing to the view that it is better to optimize what already subsists because that is easier and faster and will meet with less resistance than running an organized, engineered, name-change initiative. Implementing a radical change is harder than incrementally enhancing an existing one.” ― David J. Anderson, Kanban.
The Kanban process itself is relatively simple. It includes a Kanban board that has several cards. Each card describes a task present on the board and also describes its development.
Suggested Read: Lean kanban and its advantages
Generally, a card is used to send information to an upstream user. After that the card request parts from someone who will pull those particular parts and that suitable quantity from a storage location such as a parts supermarket. When parts are expended, either through the parts supermarket or directly from the downstream way, a sure unit of consumption would trigger a production Kanban card to be sent back to the producing method else would trigger new production.
Below is an illustration of how a Kanban system works
There are some principles that need to be followed when introducing a Kanban system. These are put in place to preserve the integrity of the system. One is imperfect parts are not sent to the next process. This would cause critical issues for internal and external customers. Anything that is faulty is pulled instantly and sent to a holding area.
The second principle is the downstream procedure comes to withdraw only what is required. This is important for more than one reason. If you are requesting more than what is needed, then you throw off the inventory storage balance. If you hold more than you can store, you will have excess material to organize. And, if you transfer too much material to the next procedure station, they are not ready to use it.
The third principle is the upstream process only produces to reload what was withdrawn. You never take more or less than what is required. The system is designed for particular quantities for a reason.
The next principle is parts must not be formed or delivered when there is no requirement. You do not create or get ahead for protection or a buffer. If you send parts or produce prematurely, the internal customer is not preapared to produce, receive, or process it.
Also read: DMAIC approach in lean six sigma
Another important principle is Kanban cards must be involved to the actual parts or container. It is very significant that the card stays with the material to eliminate confusion or faults. You do not want an operator or person to memorize or guess what the quantity should be going forward. There is no matter who processes it or where it is in the process, the quantity will always be exact.
At very last, the real quantity of parts in the container should match the number on the Kanban card. The information must be correct to be effective. Managers and operators must conduct consistent audits of the process to make sure the supplier delivery quantity and quality is the same or lead times have not changed.