MUDA is one what we call the “3Ms” . The other two are MURI, overburden, and MURA, unevenness. Eliminating all three of these will result in efficient, rationalized production.
MUDA : Non-value added or waste
MURI : Overburden
MURA : Unevenness
MURI, or overburden, is at opposite end of the spectrum from MUDA. MURI is pushing a machine or person beyond natural limits. Overburdening people results in safety and quality problems, and overburdening machinery is a direct cause of breakdowns and defects.
MURA, the third of the 3M’s, can be viewed as combination of the first two M’s: at times there is excess capacity and at time overburden. Such unevenness results from an irregular production schedule or fluctuating production volume.
MUDA, is an automatic result of because unevenness in production levels means that it is always necessary to have on hand enough equipment, materials and people for highest level production–no matter what the level may be at any given time.
The first step toward eliminating MUDA is to learn to recognize it; which steps of the production process are truly necessary, which step add value to the product, and which steps do not?
If you look closely at the process of doing production work, you can see that there are three main types of activity that are involved.
The first is simply waste or obvious MUDA. This obvious MUDA is any step that is logically unnecessary to carrying out the job, such things as waiting around, rearranging materials, or handling parts that are not needed right away. Such activities add no value to the final product, or to the material that go into it.
Next is the MUDA of incidental operations, work that must be done under present job conditions but that add no value. Leaving the workspace to get parts or tools, or taking time to unpack parts are example of identical-operation MUDA.
The last type of activity consists of the truly necessary operations which add to value of the materials. These are processing operations–changing the shape something, changing its quality or assembling it. The higher the proportion of value-adding operations in the total work performed, the higher the level of production efficiency.
In fact, when we inspect actual job-sites we find hat MUDA is extremely prevalent and value-adding operations are surprisingly small. MUDA is everywhere, and the effort to identify and eliminate it has led to the classification of MUDA into seven categories:
- MUDA of Over-production: Producing too much or too soon.
- MUDA of Waiting: Waiting for parts to arrive or for a machine to finish a cycle, etc.
- MUDA of Conveyance: Any conveyance is essentially MUDA so should kept to a minimum.
- MUDA in Processing: It is simply over-processing.
- MUDA of Inventory: Any more than the minimum to get the job done.
- MUDA of Motion: Any motion that does not contribute directly to value added.
- MUDA of Correction: Any repair is MUDA.
The Toyota Production System attempts to eliminate all forms of MUDA, but pays special attention of MUDA of over-production.