A Kanban card is a visual representation of a single piece of work, placed on a Kanban board. You could think of the card as of a relay baton, which in a relay race has to be carried by the team members - one by one - across different stages, until reaching the finish line.
Kanban cards serve to:
- Distribute information in a single, consistent way
- Empower the team and build trust
- Explain the process to all involved parties, and encourage collaboration
- Control the flow and capacity of the workflow
- Record all relayed information and an item’s progress
Invention of Kanban cards
In Japanese, the word Kanban means “signalling card”. At Toyota’s factory floor Kanban cards were the key component signalling the need for replenishment of work. This signal would indicate to team members or suppliers downstream, that their colleagues have completed or are almost done with their work, and need the upstream team to send in some more.
Traditional manufacturing systems were grounded in push methods. Orders were worked on in large batches, often with inventory sitting on the shop floor, underutilized. Kanban operates on the concept of just-in-time production, that requests items to be worked on only when they’re in demand. Kanban cards were stored in bins, and when workers completed work on an item and needed more materials, those bins were sent to the replenishment department to stock up. And when materials were depleted in the replenishment department, card bins were sent to suppliers for new stock.
Toyota noticed that workers prefer pulling work to having work thrust upon them. We can all sympathise with that - what would you prefer: coming in to work in the morning and pulling the first item of your board, or arriving to find your desk loaded with work that someone has dumped there? Kanban cards can transform an office from push to a pull system.
What information should be on a card?
At Toyota, each card contained information on where it had come from, what type and quantity of work it required, and where it had to be delivered next. The Kanban card has since evolved, and in most electronic systems it has come to represent a work item.
Cards located on the Kanban board signify work requested to be done. They can also contain information on when the item was requested, what’s the goal of the task, and on the author or requester of the item. An important point is that the cards don’t need to contain every little piece of information - just enough to empower the team to make their own decisions to get it done.
Example Sometimes, especially in electronic systems, card information can differ depending on the type of work. For a software development team, a card for fixing a bug and for implementing a feature would contain different sorts of information. The bug reporting card would outline where and when a bug occurs in the application, while a feature requesting card would describe the expected behaviour of the new functionality.
It’s common for systems to allow the cards to contain a job number, a date of the card’s initiation, team members associated with its completion, various estimations and much more. Electronic tools are also known for giving color, design, icon or text indicators to show a card’s age, type, level of recent activity etc.
Did you know?
Kanban Tool® cards, though minimalist in design, can hold all of your task information: ID, description, assignment, due date, dependencies, attachments, estimations, priority, checklists, comments, up to 15 custom fields and more.
Give it a try - make your Kanban cards as concise or elaborate as you want to.
A tool of trust and visual control
Kanban cards establish trust because team members know exactly what to work on and when to do it. The fact that these directions can be obtained individually breeds a sense of empowerment among the team. Kanban cards grant authority and prevent from working on low priority items, which should not be in circulation before high priority tasks are done with.
A Kanban board works as a visual control system. Simply walking past a board and seeing Kanban cards falling off it can indicate that perhaps the team is overloaded. Backlog cards should not be allocated to a specific person, but team members should themselves pull those cards that they feel most able to work on. That way work is encouraged rather than being forced upon people.
However, cards distribution should be kept in check, alongside with the board, in order to protect team members. If someone is already working on their full quota, they should not be allowed to pull any more cards, until they have finished with the items they have open. Cards that have not been moving can be color coded so as to become chief talking points during the morning stand-up. Team members can explain why an item has been stuck, and can work together to see how to get that item moving.