Muda means waste, where waste is any activity that does not add value. Reducing or eliminating muda is, of course, one of the fundamental objectives of any quality-oriented person.
Taichi Ohno of Toyota identified what are called the seven wastes or seven mudas, being the most common form of muda found:
- Waste from overproduction
- Which leads to excess inventory, paperwork, handling, storage, space, interest charges, machinery, defects, people and overhead.
- It is often difficult to see this waste as everyone seems busy.
- Waste of time in waiting
- People may be waiting for parts or instructions.
- Mostly they are waiting for one another, which often happens because they have non-aligned objectives.
- Transportation waste
- Poor layouts lead to things being moved multiple times.
- If things are not well place, they can be hard to find.
- It can aggravate alignment of processes.
- Processing waste
- Additional effort may be required in an inefficient process.
- Inventory waste
- Excess buffer stocks a whole host of sins, which will be uncovered by gradually lowering inventory (doing it all at once will cause total breakdown!).
- Waste of motion
- This includes movement of people, from simple actions when in one place to geographic movement. Having everything to hand as it is needed reduces motion muda.
- Waste from product defects
- Defects cause rework, confusion and upset a synchronized set of processes.
A simplified view of muda is:
- Wasting time.
- Wasting a consumable resource, such as materials.
- Causing dissatisfaction (including incomplete satisfaction).
Muda is one of the ’3Ms’:
- muda, or waste,
- mura, meaning irregular, uneven or inconsistent, and
- muri, meaning unreasonable or excessive strain.