Mura
Mura is the lean term for unevenness or variability in workload, flow or demand. Fluctuating volumes force systems to size for peaks, creating idle time at troughs and overburden at peaks, and it is a root cause of waste.
Mura describes the irregularity that makes flow lumpy — uneven order patterns, inconsistent cycle times, or surging then stalling production. It is harmful because it generates both waiting and overload, and pushes inventory up as a buffer. Heijunka, the levelling of volume and mix, is the principal countermeasure. Tackling mura often removes the conditions that create muri and muda, making it the upstream of the three lean enemies.