What is ‘Muda’?
MUDA means: Any activity in your process that does not add value.
MUDA is not creating value for the customer. In short: WASTE
2 types of Muda
- Type I muda: Non-value-added tasks which seem to be essential. Business conditions need to be changed to eliminate this type of waste.
- Type II muda: Non-value-added tasks which can be eliminated immediately.
What is ‘Mura’?
MURA means: Any variation leading to unbalanced situations.
In short: UNEVENNESS, inconsistent, irregular.
Mura exists when workflow is out of balance and workload is inconsistent and not in compliance with the standard.
What is ‘Muri’?
MURI means: Unreasonable, impossible, overdoing and overburdened.
MURI is any activity asking unreasonable stress or effort from personnel, material or equipment.
In short: OVERBURDEN
For people, Muri means: a too heavy mental- or physical burden. For machinery Muri means: expecting a machine to do more than it is capable of- or has been designed to do.
Usually the three of them can not be seen separate. When a process is not balanced (mura), this leads to an overburden on equipment, facilities and people (muri) which will cause all kinds of non value adding activities (Waiting is also an activity!!) thus leads to muda.
To eliminate MURA and MURI larger parts of the system need to be looked upon. Besides a process or process step or operation, look at an entire Value Stream. Makigami, VSM or ‘Process Kaizen’ eliminates MUDA.
How to eliminate Muda – Mura- Muri?
- Design the system with sufficient capacity to fulfill customer requirements without overburdening people, equipment, or methods (MURI)
- Strive to reduce variation/fluctuation to a bare minimum (MURA)
- Then strive to eliminate sources of waste! (MUDA)
BUT REMEMBER: Quality first, then cost – first stop shipping scrap.
– Mura and Muri are most of the time the root causes of Muda
– Muda has also root causes itself.
– Muri and Mura also.
– Muda type II is easy to eliminate and gives quick results…. but for how long?
What to look for
- Take a careful look at your Mura and your Muri as you start to tackle your Muda.
- Ask why there should be any more variation in your activities then called for by customer behavior.
- Then ask how the remaining, real variation in customer demand can be smoothed internally to stabilize your operations.
- Finally ask how overburdens on your equipment and people — from whatever cause — can be steadily eliminated.
This will be hard work and will require courage because it will sometimes require you to re-think longstanding sales, management, and accounting practices that create the Mura and Muri.
However, if you can eliminate Mura and Muri at the outline to create a stable environment for your sales, operations, and supply management teams, you will discover that Muda can be removed much faster.
And once removed, it will stay removed.
Pitfalls when eliminating MUDA
1. MUDA eliminated only taking in mind MUDA means that the MUDA can come back like a sniper.
2. Before improving a system, it is essential to first create stability.
Attaining ‘basic stability’ in the 4 Ms (men, machines, material, method) is the essential pre-condition for sustained expulsion of Muda from any gemba!
3. Without a basic stability, Mura will be present due to variance!
This is a reason to implement OEE and even TPM before trying to create flow through lean initiatives.
Why? Well, how can you create flow (= eliminate muda) when machine performance is unstable?
4. ‘Muri’ experienced by machines, gives rise to Mura in their performance!
See also:
TPM is your basic Muda reduction toolbox.
Six Sigma is your Mura (variability) reduction toolbox.
(Thanks to Peter Schilling)