Also called unevenness, variability
What is mura?
The Japanese word for unevenness: a schedule that lurches between flat out and idle.
What else it is called
- Other names
- unevenness, variability
- In French
- irrégularité
Related entries
Understanding mura
Unevenness in how work arrives or is scheduled. A plant that runs twelve-hour days for a week and then has people sweeping floors the next is experiencing it, and the cost is paid in premium labour, rushed quality and equipment run hard then left cold.
It is worth keeping separate from waste because it is upstream of it. Lumpy demand forces you to carry inventory to smooth it, to staff for the peak, or to miss deliveries at the peak. Each of those shows up later as something on the seven wastes list, but attacking the symptom without the cause means doing it again next quarter.
It also travels. A manufacturer who orders erratically from a supplier is creating the same problem one step back, and that supplier prices it into your quotes whether or not either of you discusses it.
In practice
Plot your weekly overtime hours across a quarter. A sawtooth means the schedule is doing it to you, and no amount of effort on the floor will smooth it.
Frequently asked
Is unevenness always the customer’s fault?
Rarely entirely. Some demand genuinely is lumpy, but a good deal of unevenness inside a plant is self-inflicted through batch sizes, month-end pushes and order release practices. Separating the two is the first useful step.