Muda is any activity that does not add value for the customer. Some of these activities can still be necessary from a company standpoint (compliance or finance), but are not necessary for anyone. You can spot waste by going to the gemba and see for yourself. Muda is usually caused by muri and muda, but these two are often overlooked in change efforts. When you focus solely on muda you risk not solving the root cause of a problem and thereby adding more wastes.
Muri is about overburdening your employees and machines. Overburdening equipment or operators by requiring them to run at a higher or harder pace with more force and effort for a longer period of time than equipment designs and appropriate workforce management allow. You recognize muri when you see this:
- Bad maintenance of machines, causing downtime
- Bad training for employees, causing insecurities and defects
- Unclear instructions and standards, creating insecurities
- Unpredictability in processes and machines, creating insecurities, defects, inventory and waiting among others
- Poor communication routes
- Setting goals that are not realistic
- Not adjusting your processes and number of machines or operators to peak demand
Mura jeans that there is unevenness in an operation. You can recognize mura because demand for each process in a value stream is unequal over time. You will hear people say that customer demand is erratic and unpredictable. There are usually patterns, but they are not always known or these patterns appear hard to influence. We fail to smooth out production and try to rush as fast as we can from one large batch to the next with little thought as to what the customers actually need. In a company I worked in they had a hockey stick in customer demand during the year. At the end of each year it was very busy and often very stressfull. Mura can cause overproduction, waiting and inventory among others.
Can mura happen without muri or muda?
Yes, mura can happen without muri. Mura is about unevenness in your demand and in your processes. Depending on your available resources, time, training, maintenance and standards this unevenness does not have to lead to muri.
Mura will almost always lead to muda. Unevenness will lead to solutions to still be able to deliver on time, like inventory and overproduction. When you fix the inventory or overproduction, but not the unevenness both inventory and overproduction will soon be back in place just to meet customer demand.
Can muri happen without mura or muda?
Yes, muri can happen without mura. Mura is about overburdening you employees and machines. This overburdening can coincide with unevenness in demand, but it can also happen without unevenness in demand. for instance because of lack of standards, training or maintenance.
Muri will almost always lead to muda. Overburdening will lead to defects and wait time. People will try to lift the burden by implementing solutions like inventory and extra checks (overprocessing).
Can muda happen without mura and muri?
Yes, muda can happen without mura and muri. Each of the 8 wastes can happen without unevenness or overburdening. It is always important to check whether it is solely muda that is causing the problem. If there is also mura or muri, just removing muda will not solve your problems.
How to fix muri, mura and muda?
There are many tools available for this. It is always important to keep looking for root causes. Waiting and defects may well be caused by muri. If this is the case, a poka yoke instruction may not be enough to fix it.
These are the tools you can think of. I will look at each in more depth in later blogs:
- Standardization: Having your processes fully documented and everyone trained in the best way of performing them ensures that everyone is able to do the work easily and in the best way possible. Make sure that you keep the standards alive by improving on them all the time.
- 5S: seeks to remove unreasonable movement and stress by ensuring that everything is exactly where it should be for the most efficient use. It also ensures that your layout is clear and that deviations from what is required are obvious to everyone enabling issues to be corrected immediately. The 5S’s are seiri, seiton, seiso, seiketsu and shitsuke. In English these have been transformed to 5C: Clear out, configure, clean and check, conformity and custom and practice.
- Total productive maintenance (TPM): A well thought out TPM program that utilizes everyone will ensure that disruptions and problems associated with your tools and equipment are minimized.
- Jidoka and poka yoke: jidoka stands for automation with a human touch. While poka yoke means that your processes and machines support your employees in such a way that they can’t get it wrong.
- SMED: Single Minute Exchange of Die is a simple process related to 5S and to TPM that concentrates specifically on machine setup. We reduce setup times to ensure that we have the flexibility with our machines to run smaller batches helping us to smooth out our production and make things more flexible. It allows us to ensure that changeovers are done smoothly using the right equipment, process and with fully trained individuals.
- Production leveling: Try to use heijunka to level out your production. Make the batches as small as possible and see how you can influence the demand patterns.
- Kaizen: You need to keep on improving by using kaizen/Plan-Do-Check-Act
As you can see muri, mura and muda all influence each other. You need to be able to recognize all three and get at the root cause of a problem. The best way to do this is by going to the gemba, mapping the value stream, improving on the value stream and coaching employees by using appreciative inquiry and kata.