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Lean and the 3 Factors of Waste

Start talking about lean and almost everyone starts thinking about waste elimination, which is good, mostly. You see what they are usually talking about is removing non-value-added tasks and activities which is certainly important and if that's all you did you would most certainly move forward. From a lean perspective we need to think about it in a wider sense, we need to think about the 3 different types of waste – Muda, Mura and Muri, I call them the 3 factors of waste.  


When Toyota started looking at waste in their systems they too started looking at what things they were doing that added zero value to the customer, things that the customer just wouldn't want to pay for (That's the real test to understand if it's waste or not!). They quickly hit on identifying the non-value add waste which is labelled Muda, but soon they discovered other forms of waste as well. They discovered that variations in processes were at the root cause of many issues and so created waste, this was called Mura and they also realised that when you place unreasonable stress on people, materials and equipment then you get waste as well, this is called Muri. By considering all 3 wastes as an all-encompassing system it becomes far more accurate at identifying, classifying and solving waste issues.

Muda – Waste

Muda or waste as we have said is anything that ultimately the customer would not be happy to pay for, it's non-value adding, so people instantly think about rework or perhaps manufacturing to tighter tolerance levels that are required, moving things around just because and inventory. However, it's more than that, especially when applied to a service or office environment. 

Toyota realised that within the Muda, within the waste there were 2 sub types. There were things that needed to happen to ensure the products got out the door but added no value to the customer, yet if they didn't happen there was no way the product would ship. These items they classify as Type 1 waste or necessary waste. You cannot remove them but you certainly want to try and reduce them as much as possible, so a lot of administration work, for example, would fall in here.
Type 2 waste or unnecessary waste should be eliminated in its entirety where possible, this is the traditional waste that everyone will think of, so rework, excess inventories and movement would be typical examples.

Mura – Unevenness

Mura or unevenness is certainly one of the less well known and less attached forms of waste within the lean systems. Remember that one of the fundamental principals of lean is to create flow, having flow is about eliminating batches. The issue with batches is simple, you go from feast to famine in terms of work and it glugs or pulses through the plant at a very slow rate. This results in a lot of waiting time, lots of the wrong stuff getting made at the expense of the stuff you can sell today. From an admin point of view you could think about a call centre, where all the calls hit at 9am, then nothing until 11:30am then all quiet till 3pm. The focus on Mura is to remove this unevenness within the processes and smooth the flow which reduces the overall burden on everything. Tools such as load levelling (heijunka) or kanban are typical tools that would be used here.

Muri – Overburden

Muri or overburden is probably the least well know, certainly, the least talked about element of the three elements. Muri has a few connotations, firstly think about it as exactly what we called it, overburden, you have someone working pretty hard and they are really good, so you give them more to do, and more and more and.. then you break them because you gave your 'willing horse' more than they could realistically do. Another way of looking at it is thinking about it as 'unreasonable stress' so there is a point where no matter the process, the person, the machine where it's just too much to handle and they break. The breakdown is 100% avoidable with proper design of the job, process or equipment, by looking at the load levelling, batching, vales add vs non-value add you can dramatically reduce the overburden on any single area. From a manufacturing point of view things link Total Productive Maintenance is a great way of reducing overburden on both people and machines, the machine gets regular small intervals of maintenance and the resource required to do it is spread out over time, similarly SMED (Single Minute Exchange of Die) for Set up reduction is all about making the change over easier to do, less labour intensive and more consistent, it reduces the burden on the individual(s) doing that job.

The Combination Effect

When you consider the 3 factors individually you can make great steps towards reducing a huge amount of waste in your processes and systems, when you consider them together however and apply them all then it's a multiplier, not just of 3 but of 10 or 20 times!

The next time you start reviewing a process don't just look for the obvious waste, look for all 3 elements, Muda, Mura and Muri, see how they interact, support each other and multiply the effect of your efforts.

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Thursday, 02 April 2020

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