Muda, Mura and Muri are the three enemies of Lean, that negatively impact workflow, productivity and ultimately, customer satisfaction.

These three terms are Japanese (from Kaizen method) and often used together in Toyota Production System that collectively describe wasteful practices to be eliminated.

3M Model – Muda, Mura, Muri
  1. Muda (Waste): Muda refers to any activity that does not add value to the creation of the product or service for the customer. There were 7 Types of Lean Wastes identified in manufacturing processes. Removing them was believed to be the key to value delivery to customers. Later on, the 8th Lean waste was added – Underutilization of Skills.
  2. Mura (Unevenness, fluctuation, variation): Mura refers to inconsistencies in business operations leading to fluctuations in production. Variation in production or process leads to sub-optimal utilization of resources. Uneven workloads, inventory accumulation, and waiting are some examples. The presence of Mura leads to Muda.
  3. Muri (Overburden): Muri takes place when there are too much stress and strain on people and machines. Overtime data in offices and over-utilization of machinery in plants are some examples. When processes are not scheduled to optimize resources, it can result in dissatisfaction amongst people or downtime for machines. Although outcomes might be met. Muri also leads to Muda.

7 Types of Lean Wastes (Muda):

  1. Over Production: Production of greater quantities than customer’s demand.
  2. Inventory: Row material, work in progress or finished goods which are not having value added to it.
  3. Waiting: People or parts that wait for work cycle to be completed.
  4. Motion: Unnecessary movement of people, parts or machines within a process.
  5. Transportation: Unnecessary movement of people, parts or machines between processes.
  6. Rework: Non right first time repetition or correction of a process.
  7. Over Processing: Processing beyond the standard required by the customer.