Kanban
Kanban is a workflow management method designed to help you visualize your work, limit work-in-progress (WIP), and maximize efficiency (or flow). It originated in manufacturing and has been widely adopted in software development and other knowledge work domains.
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Definitions
Kanban in Lean Manufacturing
In its original context within lean manufacturing, particularly the Toyota Production System (TPS), Kanban is a scheduling and signaling system designed to achieve Just-In-Time (JIT) production. It uses physical cards (Kanban cards) to signal the need for more materials or parts from an upstream process. When a downstream process consumes a part, its Kanban card is sent back to the supplier process, which triggers the production of a replacement. This pull-based system minimizes inventory, prevents overproduction, and highlights bottlenecks in the production line. The core idea is to produce only what is needed, when it is needed, and in the amount needed.
Kanban in Software Development and Knowledge Work
In software development and other forms of knowledge work, Kanban is a method for managing and improving workflows. It focuses on visualizing work, limiting Work in Progress (WIP), and maximizing flow. The central tool is the Kanban board, a visual representation of the workflow, typically divided into columns like 'To Do', 'In Progress', and 'Done'.
Key Concepts:
- Visualize the Workflow: Tasks (represented by cards) move across the board from left to right, making the status of every work item visible to the entire team.
- Limit Work in Progress (WIP): Each 'in-progress' column has a limit on how many tasks it can hold. This prevents multitasking, reduces context-switching, and exposes bottlenecks. When a column is full, no new items can be pulled into it until an existing item is completed.
- Manage Flow: The primary goal is to create a smooth, predictable flow of work. Teams measure metrics like cycle time (time to complete one item) and throughput (items completed per unit of time) to identify areas for improvement.
- Make Policies Explicit: The team defines and agrees upon the rules for moving cards, such as what 'Done' means for each stage. This creates a shared understanding of the process.
- Implement Feedback Loops: Regular meetings (like daily stand-ups or service delivery reviews) are held to discuss the flow of work and identify opportunities for improvement.
- Improve Collaboratively, Evolve Experimentally (using models & the scientific method): Kanban is not a rigid framework but a method for continuous improvement (Kaizen). Teams are encouraged to experiment with their process to make it more effective over time.
Example: A software team's board might have columns: 'Backlog', 'Ready for Dev', 'In Development (WIP: 3)', 'In Testing (WIP: 2)', 'Ready for Deploy', 'Done'. The WIP limits ensure developers don't get too far ahead of testers, promoting a balanced and efficient workflow.
Origin & History
Etymology
The term 'Kanban' is Japanese, derived from 'kan' (看), meaning 'sign', and 'ban' (板), meaning 'board'. Combined, it translates to 'signboard' or 'visual card', which directly relates to its core practice of using visual signals to manage work.
Historical Context
The concept of **Kanban** was developed by industrial engineer Taiichi Ohno at Toyota in Japan during the 1940s and 1950s. It was a cornerstone of the Toyota Production System (TPS), a revolutionary approach to manufacturing that aimed to eliminate waste (muda), inconsistency (mura), and overburden (muri). Ohno was inspired by the inventory management practices of American supermarkets, where shelves were restocked only after customers had purchased items, creating a 'pull' system. He applied this logic to the factory floor, using physical cards to signal when a downstream process needed more parts from an upstream process. This 'just-in-time' (JIT) system dramatically reduced inventory costs and improved efficiency. For decades, Kanban remained primarily a manufacturing concept. In the early 2000s, its principles were adapted for intangible goods and knowledge work, most notably by David J. Anderson. In 2004, while at Microsoft, Anderson applied Kanban principles to a software maintenance team, creating what is considered the first implementation of the Kanban method for software development. He formalized the method, emphasizing concepts like visualizing workflow, limiting work in progress (WIP), and managing flow. His 2010 book, "Kanban: Successful Evolutionary Change for Your Technology Business," was instrumental in popularizing the method across the IT and software industries, where it is now a widely adopted alternative or complement to other Agile frameworks like Scrum.
Usage Examples
Our development team uses a digital Kanban board to visualize tasks and manage workflow, which has significantly reduced our cycle time.
By implementing strict WIP limits on our Kanban system, we were able to identify and resolve bottlenecks much faster.
In the factory, a physical Kanban card is sent upstream to signal the need for more parts, embodying the principles of just-in-time manufacturing.
Instead of working in fixed-length sprints, the team opted for a continuous flow model using the Kanban method.
Frequently Asked Questions
What is the primary purpose of Work in Progress (WIP) limits in a Kanban system?
WIP limits are crucial for preventing team members from being overloaded, reducing the inefficiency of context switching, and exposing bottlenecks in the workflow. By limiting the number of tasks in any 'in-progress' state, it forces the team to focus on completing existing work before starting new work, which leads to a smoother, faster, and more predictable flow of value.
Where did the Kanban method originate?
Kanban originated in the 1940s at Toyota in Japan as a key component of the Toyota Production System (TPS). It was developed by Taiichi Ohno to create a lean, just-in-time manufacturing process.
What are the six core practices of the Kanban method for knowledge work?
The six core practices are: 1. Visualize the workflow. 2. Limit Work in Progress (WIP). 3. Manage flow. 4. Make process policies explicit. 5. Implement feedback loops. 6. Improve collaboratively, evolve experimentally.