In his book about Kanben David J. Anderson mentioned 2 approaches how to handle WIP-Limits when installing a Kanban System.
Adding Buffers or Queues
Approach #1 – Self-Revelation
Two variants are possible here:
- Don´t add buffers, instead let the bottleneck reveal itself. Only when you identified it add buffers to protect it.
- Set WIP-Limits loosely first so that variablitiy, waste and bottlenecks don´t impact the pull system
Approach #2 – Buffers everywhere
Buffer every stage and set tight WIP-Limits for every activity. Bottlenecks will then reveal themselves, too. Then adjust by reducing buffers as needed, or removing them at all where they are not needed.
Agreeing on WIP-Limits
Choosing WIP-Limits is one of the most important decisions when introducing Kanban
Recommendation by the author: WIP-Limits should be agreed with up- and down-stream stakeholders and with senior management. Later, when the team is put under stress a collaborative agreement will make negotiations about workload and replenishment easier.
