Most people that have been involved in Lean will be familiar with the principles that waste exists to some degree in every single activity we perform. Whether it is at work or in our day to day business. And in order to improve our processes and become Lean, we must remove waste.

Most will also be aware that in general waste is split in 7 types or categories:

  • Transportation
  • Inventory
  • Motion
  • Waiting
  • Over Production
  • Over Processing
  • Defects

Normally remembered by the acronym TIM WOOD.

But my question is this, how many realise that this is only part of the big picture in understanding ‘waste’, its effects and how to address it. TIM WOOD can only help us so far along our Lean journey.

To fully understand this we need to go back a step and really try to understand some of the core fundamentals of Lean. Let’s start at the very beginning and understand why the removal of wastes within processes is judged so important.

The single most important factor in developing a lean process is the ‘Voice of the customer’. Understanding what the customer needs, in what volume, and when it is needed.

Having understood this, the next step is to develop a system that will deliver to the customer needs on time, to the correct quality, in the right volume. Sounds simple but this is where the problems start. If the process is not flexible enough to meet the changes in customer demand, inefficiencies creep in and hence the level of waste within the process grow.

This is where most peoples understanding (including many lean practitioners) of waste starts to break down.

You may have heard the term ‘Muda’. Muda translated from Japanese is Waste. However this is only part of the story.

When Taiichi Ohno, Sakichi Toyoda, and Kiichiro Toyoda, originally set out to develop the Toyota production system, they recognised that the root causes of waste in a process were much deeper than many consider today.

They defined 3 types of waste, MUDA, MURA and MURI

What has happen is that Muda has been given much greater attention since over time it has been well defined into the 7 categories I mentioned earlier. Because of this, many Lean practitioners have learned to see just Muda, they fail to see in the same prominence the wastes of Mura (unevenness) and Muri (overburden). Whilst they are focused on getting their process under control they do not give enough time or consider to the impact of the other two types of waste.

So let’s take time to consider both Mura and Muri.

Mura or unevenness occurs at a number of levels within a process and needs to be taken into account when ‘Just in time’ is being put in place. Consider this, what happens when we reduce or remove inventory (one of our 7 classic wastes)?

Well, now that the safety buffer has been removed, the process will be put under strain to deliver in a much more responsive way. The entire value chain will be asked to flex up and down in speed. The impact of this change can be devastating to the organisation. Manning levels have to be adjusted (If cost and efficiency are to be maintained), Suppliers will be asked to change delivery schedules at short notice. Maintenance schedules may need to be changed. In fact a whole plethora of issues arise and all take time to manage. Also, because of the need to produce at peak volume at any time, in theory equipment, workers, inventory and all other elements required for production must always be prepared for peak production. This adds both cost and waste.

Unless systems and processes are put in place to do this, waste starts to creep back into the process.

Toyota considered this in the development of the Toyota production system. It took it into account with the concept of Heijunka or production smoothing. The concept of Heijunka may at first appear to contradict the ‘Just in time’ and lean production philosophies. But it must be remembered that done correctly small amounts of well managed strategic stock will both aid efficiency and lower overall cost.

In general, the concept of Heijunka is to try and smooth the production rate within acceptable limits. There are a number of tools and tricks to this which are again linked to the original thoughts behind the Toyota production system.

For example, Toyota’s final assembly line never assembles the same automobile model in a batch. Production is levelled by making first one model, then another model, then yet another. The pattern or order of the 3 models is then adjusted to smooth the daily rate based on customer demand (take time). This flexibility is one of the key reasons for having a mixed model process. But in order to achieve this Standard, work must be well defined and implemented otherwise the waste of ‘MURI’ will be the issue.

Muri or overburden, generally occurs when Standard work is not well defined or when additional tasks have been placed upon someone through a process change without consideration to their other workload or line balance.

Within most companies it is the case, but the importance of Standard Work cannot be underestimated. A smooth process with well trained people has a number of other benefits. When everyone knows the standard condition, and the standardised work sequences, heightened morale is seen. Normally along with improved quality, improved productivity and reduced costs.

So when you are next observing a process for waste, look a little deeper. Look for the 3 M’s consider MURA and MURI and think deeper than just the classic 7 wastes.

Want to know more ?

If you would like to know more about Muda, Mura, and Muri or would like to know how LMAC could help your business with its Lean programme   Contact us



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