MUDA, MURA, MURI are three terms often used together in the Toyota Production System (and called the Three Ms) that collectively describe wasteful practices to be eliminated.
Muri is the Japanese term for “overburden, unreasonableness, beyond one’s power”. It means pushing your team beyond their capacity. While this is obviously a problem, how does it relate to waste?
Muri is deeply intertwined with the other two types of waste, Muda and Mura. Mura (unevenness) leads to teams alternating between being overloaded with work and having nothing to do.
Many Mudas – Overproduction, Overprocessing, Motion, and Transportation – unnecessarily increase the workload for teams. Muri can also cause Muda. For example, a team rushing to complete a deadline without enough time to do it properly will cause the defects and unintended re-work due to problems in quality.
The key to reducing Muri in a team’s process is to ensure demands are brought in line with the team’s capacity.
When demand (load) and capacity are as close to equal as possible, workflow becomes smooth, streamlined, and efficient. Streamlined workflow leads to consistent results and improved throughput.
Reducing unevenness in your process will cause a parallel reduction in Muri and should be made a high priority. Visualize your entire process step by step – what steps cause unnecessary work for your team? Pay particular attention to the Overprocessing, Overproduction, Transportation, and Motion Mudas.
Overprocessing and Overproduction can be managed by properly defining expected results and ensuring these are clearly communicated to your team. As for Motion and Transportation, look for ways to free your team members from administrative burdens. Can any repetitive steps of the workflow be automated? Is there a more efficient “trigger” for the next stage of the process (e.g. automatic Trello notification instead of manually sending an email)?
When work is pushed onto your team without considering their capacity, Muri is bound to happen. Switching to a pull system such as Kanban can help you ensure that your team only pulls new tasks into the workflow when they have the capacity to do so.
Kanban is designed to make workflows more productive and efficient. Here are some Kanban practices that can help you keep Muri at manageable levels.
One method of stopping overburden in its tracks is to set strict limits on the amount of work in progress. New tasks are not allowed to enter a stage in the process until an outstanding task has been completed. It’s important to pick the right WIP limit for each stage of your process. The best limit is low enough to make sure all tasks are being worked on, and high enough to keep your whole team busy at all times.
Use explicit policies and Kanban rules to prevent forming bottlenecks and stalled work. In specialized teams, splitting the workflow into swimlanes for each specialist or specialist subgroup gives you clear visibility on the workload of each team member. Each swimlane requires its own WIP limit.
Bottlenecks signal that some part of your process is overburdened. Find your bottlenecks by visualising your process in a Kanban board and performing deep analysis over it using a cumulative flow diagram.
The ultimate goal of reducing waste is to improve productivity. Kanban suggests several productivity metrics that you can use to observe how the changes you are making are affecting your process. The positive results from making continuous effort to reduce Muri and the other wastes should show in your throughput and cycle time figures over time. Track how these figures are changing using:
1. Siderova, S. (2019) Lean Manufacturing Wastes: Muri