When it comes to the Japanese terms Muri, Muda, and Mura, more often than not people will put Muda first, because it refers directly to the waste being avoided within the system, and although it is of vital importance, the order should be:
Mura: Before we can do anything else, we must first plan and develop a system that involves no Mura. There must be no inconsistencies and unevenness. If there is, it must be smoothed out to avoid creating Muda, the useless waste. This will ensure that when all other processes are set up, they will be following a consistent standard. All the processes together must first gain a reasonable level of unevenness by capacity.
Muri: When Mura is in place, and the inconsistencies are still not yet reduced ideally, Muri will quickly surface. There are areas where Muri occurs beyond the consideration of Mura; such as having a high defect ratio, or the occurrence of bottle necking due to difficult operation.
Muda: Once the Mura and Muri had been sorted out, then it will be time to identify the waste, or Muda, in all the operations. These wastes can be reduced which will positively affect the process of Heijunka, or production leveling.
T: Transportation: Muda (waste) in transportation. Examples: amount of loads and distance traveled.
I: Inventory: Muda (waste) of superfluous stocks because of unfavorably timed deliveries, abnormalities, over-processing and over-production.
M: Motion: Muda (waste) of motion such as over-laboring.
W: Wait: Muda (waste) in time, such as idling; perhaps as a machine completes its cycle, or because the material is not being delivered on time.
S: Space: Muda (waste) due to over-processing. Poor Utilization of Space causes additional costs for storage.
O: Over-production: Muda (waste) due to over-producing. Inventory becomes full, there is no space for new product and tracing quality and quantity becomes difficult.
– by WayDocs.com