3 Mu the Killer Virus!

3 Mu the Killer Virus!

It is shocking but true, almost all manufacturing shop-floors are inflicted by the 3Mu Virus! This infection can in fact extend beyond the shop-floor and inflict the entire organization or supply chain! But today, we will restrict our discussion to the shop-floor. Though it is a common virus, sadly it is not easy to identify or kill and it is really challenging to keep it out forever!

3 Mu’s – muda, Mura and Muri are three Japanese words that roughly translate into Waste (non valuing adding), Variation and Excess Physical Burden. Just like human health is dependent on the total absence of any kind of virus (and other pathogens); similarly shop-floor ‘health’ can be determined by presence or absence of the 3Mu virus. In this part of our writing, we are attempting to provide an overview of the three killer viruses.

We shall explore this virus, from three dimensions:

  • What is it?
  • Symptoms!
  • Cure/ Precautions

 1st Mu – the virus called Muda:

 What is it?

It is a Japanese word that means ‘waste’. Here we refer to waste in activities within processes and not really waste in its physical form. That heap of material sitting as defects/ scrap on the shop-floor is not really referred to as muda (waste). muda in this case will be the wasteful activities involved in ‘inspecting’ the production to find the defects or the rework that follows defect detection.   So ‘rework’, ‘inspection’, here are the Muda’s (wasteful activities). These activities are performed by people; it costs money to perform, consumes resources, but adds NO value. Activity that costs money; but adds no value to the customer (internal or external) is muda – the first & worst kind of shop-floor virus!


muda is classically seen in eight forms:–

  1. unnecessary material transportation,
  2. unnecessary motion of people… hands, feet, eyes!
  3. rework/ inspection due to defects,
  4. people, material or machines waiting for each other
  5. unnecessary processing – over kill!
  6. unnecessary production – producing more or faster than required
  7. unnecessary inventory – in any form raw, work in progress or finished goods
  8. finally the killer – unused human skills/ potential


 There is no hope for cure unless one first has the expertise and skills to identify the muda virus. In fact, identifying muda by itself is half the cure! Though cures are available off the counter; but self-prescription can be dangerous! The cure, in fact, starts with mental acceptance (that our shop-floor is inflicted), followed by clear identification, measurement of the intensity of infection and finally following the prescribed cure. All the above eight muda can be measured; if they can be measured they can be improved!

Symptom and Cure:

1) Unnecessary material transportation – layout redesign, FLOW / cellular production,

2) Unnecessary motion of people – apply principles of work station design and motion economy

3) Rework/ inspection due to defects – eliminate causes for defects at the root

4) People, material or machines waiting for each other – needs multi pronged treatment – use TPM, SMED, FLOW, Internal Logistics etc

5) Unnecessary processing – over kill! – define customer needs, stick to it!

6) Unnecessary production – producing more or faster than required – Line balancing, follow Pull production, Levelling etc

7) Unnecessary inventory – in any form raw, work in progress or finished – this automatically reduces, as other symptoms are treated! However KANBAN, Pull planning etc can help

8) Finally the killer – unused human skills/ potential – TEE – Total Employee Engagement, TWI – Training Within Industry and DWM Daily Work Management are proven cures in this case.

The above listing of the problems and cure might look naïve. It is easier said than done. On paper one can tone the symptoms down or make it look grave, similarly the cure can be made to look simple or very daunting! I don’t want to give the reader a feeling that attacking or managing this virus (Muda) is easy, a cake walk! At the same time nor do I want the reader to think that the task on hand is impossible or that the prognosis is poor!

2nd Mu – the virus called Mura:

What is it?

Mura means Variation. Variation means deviation from a set standard or expected outcome. Mura – Variation from expectations is a rampant virus, inflicting all processes and work activities. Variation results in waste in the form of scrap, reworking or reprocessing. For e.g.; Two cups of coffee may not taste the same or have the same temperature!, though it is coming from the same vending machine at the same point of time, thus it may require reheating – which is a clear waste (not to mention reheated Coffee may be totally rejected by some of us!)

Coming to business, there is variation in business processes, products, materials, skills, output etc. Inspite of advancements in machines and in process technology, variation do occur and it is the management’s duty to IDENTIFY, MEASURE, ELIMINATE and keep out all variation from the processes.

Standard Deviation (SD) and it is a statistical measure of variation or variability. It is denoted by Greek letter ‘σ’ (Sigma). In the western world, the state which is almost variation free is termed at Six Sigma.

It is important to note that Mura results in muda – that is, variation results in waste (in form of rework/ redoing). Thus this Mura virus; results in another virus attack – Muda!


When the outcome expected does not happen, one can safely say that there is some Mura (variation) in the process. Symptoms, is in the form of either variations in quantity of output, or quality of the output or delays. Say, when a business process like processing of payments (payables) has a variation, either the number of payments expected to be processed in given unit of time will greatly vary or the payments processed have errors and omissions. Let us look at another simple case, like liquid filing (for say for Milk or Shampoo), if each bottle coming out of the line has more or less than the required volume, it means that there is variation in the filling line (this can be a costly variation for the company!)

Most organizations prefer to build numerous checks, counter checks and inspections into the process to ‘catch’ variation. Catching is hardly a solution, as it is done after the damage is already done!


The only sensible and permanent cure to variation is building a robust process. Go upstream and fix the causes for variation. The best way to set off in this direction is to use a simple tool – the 5 Why Analysis.  There are many tools to identify, measure and reduce process variation – the famous 6 QC tools, DOE, Shanin Tool’s etc

3rd Mu – the virus called Muri:

What is it?

Muri means avoidable physical strain/ burden on people and machines/ equipments at work. Same strain (within defined & safe limits) is to be expected at work, but when the strain becomes excessive, it becomes a burden It results in accidents, injury, leading to poor output or quality errors. A person, who in working in extreme conditions caused due to excess noise, temperature, fumes, etc, experiences Muri / burden.

Muri (overburden) on equipment means machines that are operating over its safe limits or set performance limits. Overloading, abuse, poor maintenance etc, causes Muri. It results in the equipment breaking down or performing under its expected output and quality limits.


Excess strain or Muri on an operator is to be measured through on site observations and trails. Of course at times someone sweating profusely or his strained posture while doing a job is a symptom by it self. Management must recognize it and fix it. Otherwise Muri will result in Mura – variation!

Strain/ Muri on equipments can be easier to identify. Machines will shudder, squeak, leak, stop, produce defects and finally protest and STOP! 


Muri needs to be identified, measured and eliminated. Ergonomic design of work stations, good work environment and design of standardized work, helps tackle Muri (strain).

TPM (Total Productive Maintenance) is a tested and proven approach/ system, which eliminates Muri (strain) on machines/ equipments.

Interestingly, Muri reduction results in;

  • Heightened employee morale (due to close examination of ergonomics and safety),
  • Higher quality,
  • Improved productivity, and
  • Reduced costs.

Thus these three deadly viruses muda, mura & muri combined, can result in costly abnormality for the organization.

There is an urgent need to cut muda across all shop-floors, in fact across all organization – public or private, be it a tiny, small, medium or a very large. These viruses are devouring precious resources on every shop floor – every minute, every shift, every day, everywhere – we need to arrest this shop floor by shop floor, organization by organization, before it becomes a national epidemic that cripples the our competitiveness .

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