Definition
Japanese "unbalanced, volatile".
In detail
Mura (unevenness) refers to imbalance or fluctuation in production or processes, such as demand variability or uneven workload, causing idle or overloaded resources and being a root cause of waste. In the lean system, Mura, along with Muda (waste) and Muri (overburden), are the three types of waste; eliminating Mura is the primary goal of Heijunka (leveling). Unlike Muda (specific non-value-added activities) and Muri (overloaded equipment or people), Mura focuses on variability. Outputs typically include fluctuation analysis charts and leveled production schedules.
Example in practice
An injection molding workshop's production plan fluctuated with orders, sometimes overwhelmed and sometimes with idle equipment. Through analysis, they found high demand variability, so they introduced Heijunka (leveled scheduling), evenly distributing orders by type and quantity, and established buffer inventory. After implementation, equipment utilization stabilized, employee workload balanced, and defect rates decreased due to stable rhythm.