How Kanban Improves Work FlowScott Williams
Kanban is a Japanese word that refers to an effective methodology for moving work and products through a number of stages.
It is commonly used for visual management of inventory and manufacturing and also for managing the several stages in a project.
Kanbans are a tool for structuring how work flows into the work-in-progress queues so that workers do not get overloaded and can use their time most effectively. Kanbans, and variations on them, are also widely used in software projects (e.g. Scrum and Agile) and manufacturing (e.g. Lean and Six Sigma). Blue Belt
Workflow Kanban Introduction
The fundamental principle of Kanban is to only produce something when it is required by a downstream step. This minimises the amount of inventory that builds up after a work station and ensures that it is only doing productive and on demand work.
The upstream station needs some sort of flag/signal to produce the next unit of its production. There are various ways of signalling that have been developed and some of which may be relevant to your system.
The topic of flags/signals is reasonably large but, by way of example, it could be an empty space on the factory floor or our office in-tray.
Staff are trained to respond to that empty space by immediately producing some unit of work to fill the space up again. Therefore, as the downstream stations draw product from the upstream stock pile the empty space automatically indicates the need to begin production again.
Although it is ideal to have batches as small as possible (see Small Batches Tool) it is not always feasible or possible to do just one unit at a time. Therefore, a Kanban System may have a process for drawing product steadily from a supply until a trigger point is reached, a flag/signal is sent and a new batch of x units is produced by the upstream work station.
For example, a Kanban may have a tray with several slots in it where the number of slots is equal to the optimum batch size of the upstream system. As units are drawn from the upstream inventory, a card is put into the slot and a staff member is trained to trigger a new batch from the upstream station as soon as all the slots are filled.
The Kanban’s will also need to take into account such thing as the lead time for producing the product and even further lead times for getting inputs from even further upstream stations or raw materials.
There are several standard rules for the operation of a Kanban.
- That the following process collects from the upstream only as the downstream needs.
- That the upstream only produces what is being withdrawn by the downstream unit – allowing for some batching as necessary.
- That the withdrawal of a production input by a downstream unit must trigger an appropriate Kanban signal so that the upstream is aware that the withdrawal has been made.
- That there is no production or inventory produced by the upstream station without a Kanban card to justify it.
- That there must be zero defects in whatever the upstream station produces so that there is no disruption downstream. We do not want a downstream unit drawing down the next input item only to find that it has a problem and cannot be used. Then the whole production cycle comes to a halt until the defective item can be replaced.
- Over time the goal is to reduce the number of units in a Kanban batch by continually shrinking the batches. This has been likened to lowering the water level in a lake. As the water level falls, more rocks show and therefore more problems can be resolved. While there is a lot of water in the lake, the impact of these existing problems is disguised and may never come to the attention of the operators. Smaller batches mean more efficient work and therefore the need to remove problems.
In any system, there will always be some variation and uncertainty. There is a way of measuring the seriousness of uncertainty, the Kanban can have a “fever chart” attached to it using a colour coded scheme to immediately identify whenever a problem is becoming serious (see Fever Chart article).
Project Kanban Introduction
Essentially, all Kanbans used for project management are similar in operation:
- listing out all the tasks that need to be done on a project, in a quarter or by a due date. These are added to a column of such tasks head “Backlog“
- Items in Backlog can have e.g. notes, time estimates, goals, purpose and preceding and following tasks added to build up a “Story” about the task. Anybody can add to this information repository. Such items are stockpiled here pending a decision to work on them.
- At a regular interval chosen by the team, the next highest priority items in Backlog are moved into another column to the left of Backlog which is entitled “To Do” or similar. It is recommended the intervals are kept fairly short and 2 weeks is a common setting. The idea is not to have more than (e.g.) 2 weeks of work in the To Do column. This makes the team focus on what is important and keeps the tasks to do fairly simple. If a task will take more than 2 weeks, it needs to be further subdivided until some 2 week sub tasks fall out and get added to To Do. This chosen period is usually called a “Sprint” because if the intense, short time span, focus on the chosen tasks.
- as the work team finish tasks they are working on, they drag ToDo task into the “Doing” column to the right of the To Do column. This column only contains things they are actually working on at the time so it keeps them focused on the comparatively few tasks considered to be most important at the time and thereby reduces the evils of multitasking. All these are meant to be completed in the allocated Sprint time period – say 2 weeks
Go to the article: Find the Hidden Dangers of Multitasking
- as tasks are finished, and there is consensus that they are finished, they get dragged into another column to the right of Doing headed ‘Done“. This contains everything completed on the exercise to date. One can dive in here to back check if necessary.
- generally there are team discussions at the end of each Sprint to see what can be learnt from the recent work experience. The team then goes back to the start and chooses the next round of To Do tasks from the Backlog.
- this continues until the overall exercise in 1. above is completed.
The columns can be done on a white board and the tasks on sticky notes. Or you can use software like Trello (see below) which is very simple.
Wikipedia article: https://en.wikipedia.org/wiki/Kanban
To read more about using Kanbans for moving effectively through project work read more on using Sprints.
For an interesting example of a Kanban system operating in a warehouse environment, what this real-life video of a Kanban at work
A free and widely used Kanban software tool is Trello. It should be Yellow Belt for most people. It is available on desktop and mobile devices. It is very popular and we recommend it as a starter app.
- a Yellow Belt article on using Trello for project management
- 3 minute Youtube Video
- 7 minute Youtube video
- a public Trello Kanban where you can drive the software yourself (no explanation with it, leave until you understand a little)