ASQ CQA – 5. Quality Tools and Techniques Part 7

15. 5B2 Lean – Types of Wastes – Muda, Mura and Muri

Topic of waste elimination. First, we will understand the types of wastes that will help us in identifying wastes. And then we will look at various techniques to eliminate waste. The techniques which will be covered in this course are the Pull system can ban five S standard work and poka UK. Even before we talk about types of wastes, let us understand and the philosophy behind waste.

One thing which we need to understand is that waste exists in all processes at all levels in the organization. So whatever work you are doing, whatever system processes you are following, there is always a waste there. So don’t think that your process is perfect and nothing can be improved and this is the perfect process which you can have. There is always a waste in the process. Whatever you are doing, you need to look into that and you need to eliminate that.

So once you reduce waste from your processes. Your process will become more efficient, more effective, and, in fact, that will lead to the improved profitability of your organization. Now, coming to the types of wastes. Waste could be categorized into three broad categories muda, mura and muri. These are Japanese terms. So let’s understand the definition of these. And then in next three slides, we will look into these three types of waste in little bit more detail.

Let’s start with muda. When we say waste most of the time we mean muda. Muda is the commonly known waste. So muda is an activity which doesn’t add value or which is unproductive. That’s muda. So if you are doing anything in your process which doesn’t add value to the client. Then this is called as the muda. Next type of waste is mura. Mura is any variation which is leading to unbalanced situation. So unbalanced situation means sometimes you have too much of work. Sometimes you have too less of work. Sometimes your machine is working at 110% level and at some other time this is working at 20% level. So the unevenness in the process is called as mura. This is also a type of waste.

The third type of waste is muri. Muri is any activity which is producing unreasonable stress or effort on part of people who are working or on machine or on equipment or on the material which is being used. So any unreasonable stress is called as muri. So after having this basic understanding of these three types of waste, let’s talk about muda in a little bit more detail on the next slide.

So when we talk of muda, muda is a Japanese term for any activity that is wasteful and doesn’t add value or is unproductive. That’s muda. In common term, you can call muda as non value added activities. So any activity could be value added activity. Or non value added activity. Value added activities are those activities for which your client is willing to pay. So value added activities are those activities which produce something which client wants from you. This could be a product or this could be a service but any activity which doesn’t add value to the client at the end is a non value added activity.

So when we talk of muda, muda could be of two types. Type one muda is something which is incidental work which is a non value added activity but you still need to do because the business conditions require that. For example any statutory or regulatory forms you have to fill in, any reporting which you have to do, any mandatory tests and inspections which you have to do. Those are type one muda. Type one Mudas are even though non value added tasks but still you need to do that because the business conditions require you to do that. Type two muda is something which is non value added work which you can straight away eliminate which really doesn’t add value. The simplest example of type two muda could be repair. So let’s say if you produce something and you find a defect in that and you repair that now your client is not paying you for making defects and repairing that. This is a case of type two muda or non value added work. So let’s summarize here any activity could be of two types value added activity and non value added activity. Non value added activity could also be classified as type one muda which is incidental work which you need to do and type two Muda which is a non value added activity. Now, after talking about muda now let’s move on to the next type of waste which is mura.

Mura is any variation which is leading to unbalanced situation and when this happens, when your workflow is out of balance or your workload is inconsistent for example one day you need to work too much, you need to overstay and you need to do a lot of work. The second day there’s nothing much to do. This is in regards to person, in regards to machine. Also at some place there is an order which you need to rush through and your machines are running above their limit and some other day you don’t have that much work so your machines are idle.

This is mura the unevenness or unbalanced situation in work. So to summarize, mura is unbalanced situation where you have ups and downs when it comes to the work load. The third type of waste is muri. Muri is any activity which is asking unreasonable stress or effort from personal material or equipment. So this is something which is producing stress because there is too much of work. In case of people you have too heavy a mental or the physical work which you need to do. This is producing stress to the people. This is muri. In case of machine you are expecting machine to do more than what it is capable.

16. 5B2 Lean – Eight Types of Wastes

These are transportation inventory, motion, waiting time, over processing, overproduction defects and underutilized staff or underutilized skills. So these are the eight types of muda. Now let’s go into each of these and look at what does this mean? Understanding these will help you in identifying the waste in your process. So let’s start with the first type of muda which is the transportation waste. Transportation waste is unnecessary movement of people or part between processes. So let’s say you have a plant in which you are making pieces. So here is your machine A and then machine B is here and then machine C is here at another place or another location. Or these could be three different plants. So you make some parts here and then you ship them to other place and you do some processing and you ship them to third place. So all this movement between different locations is a waste. So in case of office situation, let’s say you fill in a form here.

So person A fills in a form, then this person sends that form for approval for management. Management is sitting at a different location, location B sending that letter from place A to place B for signature that’s waste because here what it involves is transportation. So if you could eliminate this transportation from one place to another place you could reduce this type of waste. The next type of waste is inventory. Inventory is a material which is parked and not having value added to them. So when you think of inventory, think of inventory in terms of incoming material. Let’s say you are doing two processes only process A and process B. And to do this you bring in or you buy, let’s say lot of inputs here. So all the inputs which is lying here is your inventory. Now this needs to get processed. So for processing this goes to process A and after process A it has to go to process B. But what you want to do is you have done process A and then a lot of material is lying between process A and process B.

This is inventory. Then after process B which is the last process which has been done. Now you have finished product. Now there is a lot of finished product which is waiting for selling. All these are types of inventory. Inventory is something which is material parked and not having value added to them. Now, what is the big deal if you think inventory is the biggest problem when it comes to waste? The first thing is you need to pay to buy this material. All this material which is input material, in process material and the finished material, all this material which is lying in your facility, you have already paid for that but you are not getting return. So there is a cost or the money involved for holding this inventory. This is first waste. The second waste is you need to maintain this inventory. You need to preserve that so that this doesn’t get rusted, this doesn’t get damaged, this doesn’t get any problem because of water. Seepage, whatever problem this could have. So you need to protect this. So you need to spend money in preservation. Another problem which is related to inventory is this becomes obsolete. Let’s say you made a lot of these pieces as the final output.

Now the market conditions have changed. Now nobody wants this output that’s waste. Because now you cannot sell it because this is an obsolete product. Out of all these problems, the biggest problem which I feel is that inventory hides a lot of other problems as well. Inventory hides defects. And how is that? Because when you have done process number A here, after process A, you have a lot of material which is lying between process A and B. If there was a problem in process, a lot of defective pieces would have been produced which have been lying here in this inventory.

And now this problem gets hidden because nobody has noticed. Because if there was no inventory, the piece goes directly from process A to process B. The operator B will straight away find out that there is a problem with the process A, something needs to be done. But now, since we have a lot of inventory, what operator B does is operator B picks a piece which is defective, then operator B puts it on a side and takes a better piece and then starts working on that. So you are left with a lot of defective items between process A and process B. So this was another problem because of inventory. So inventory is something which you should be really working hard to remove. What you need to do is you take one piece, get operation A done, then straight away it goes to operator B. So that if there’s any problem that is straight away identified, if you identified the problem straight away, then you can take direct action on that. So this was the second type of waste.

The third type of waste is motion waste. Now, many times people get confused between transportation waste and motion waste. Transportation is the movement from one place to another place. Motion waste is unnecessary movement of people or part within a process. So let’s say I am an operator which is working on an assembly station. So for that, I need three items. So for item number one, I go and pick item number one from here. Then I pick item number two from here. Then I pick item number three from here. And then I assemble that and then I put it on the back side. So all this movement which I’m doing is a motion waste. Emotion waste is the waste within the process which I’m doing. And the transportation waste is the waste of moving things between processes. Coming to the fourth type of waste, which is wait time.

Wait time is when you have to wait for something to be done. Operator number B is waiting for operator number A to finish the process so that operator B could work on that. Management is waiting for a report to be produced and once that report is produced then they can give it to client. That’s the waiting time. So this is another type of waste which was the waste number four here. The fifth type of waste is over processing. Over processing is doing something which is beyond the demand from the customer. Customer doesn’t need this. This is also called as gold plating. Let’s be clear here, you need to do something to make customer excited. So companies always do something which makes customer excited. They give new features. But then those features are something which customers recognize that they are getting something extra. Over processing is something where you do processing which really customer doesn’t bother about that. So this is over processing. The next type of waste is overproduction. Overproduction is producing too much, too early or too fast.

Because let’s say your demand is two pieces a day and your machine can produce four pieces a day. So what you want to do is to keep your machine running. You keep on producing four pieces a day which is overproduction because you want to keep your operator busy. But what it is leading to is overproduction. And overproduction leads to inventory and inventory leads to a lot of other problems. So what you want to do is produce only and only when something is needed. Later on we will be talking about the pull system. Pull system is driven by the demand. So you produce something based on demand only, not based on how much you can produce. Coming to the next type of waste which is defects. So this is most well understood type of waste. So if you are producing something and you are producing defects in that, that is leading to a lot of problems. Because if you produce defects then you need to do inspection.

You need to sort out good items from the bad items, then you need to repeat the process, you need to repair that and then some of these items will be scrapped. So all this is waste. So this was the waste number seven and the waste number eight which was added later on. Because initially when these wastes were listed down there were seven types of wastes. This is the 8th, the type of waste which was added later on, which is underutilized the staff or underutilization of skills.

So if organizations fail to exploit the full knowledge and talent of employees, that is also a big waste because each operator, each worker whosoever is working in your organization has a lot of skills and knowledge, you need to utilize that. And if you fail to utilize that you are wasting a very valuable resource here, which is the skill or the knowledge of staff. So these are eight types of wastes. So if I have to summarize these eight types of waste, I will summarize these with this term, which is Tim Woods. And this will help you in remembering all these eight types of waste in Tim Wood.

T is for transportation waste, which is here. I is for inventory waste. M is for motion waste. W is for waiting time. These first two, one is overprocessing, and the second is over production. These are two types of waste. And then we have D for defects and S for skills. So if you have to remember these eight types of waste, you remember these with this term tim woods, transportation, inventory, motion, waiting time, overprocessing, overproduction effects and skills. So this completes.

17. 5B2 Waste Elimination – Pull System

Are the pull system kanban, five S, standard work and poke Aoki. Let’s start with the pull system first. So when you say pull system, the opposite of that will be the push system. Let’s understand push system first. In push system we produce things and then we wait for these to be sold. So let’s say I have a factory where I can make 100 pieces. So it has to go through, let’s say three processes. Process A, process B, process C and this chain of process A, B and C can produce 100 items per day. So what I do is to keep my operators busy, to keep my machine busy, I keep on producing 100 pieces per day and then I wait for these to be sold out. So here what I’m doing is I’m producing based on my capacity or maybe based on my forecast and then waiting for these to be sold.

So this is the push system. And what you end up in push system most of the time is a huge pile of inventory because you have produced something based on the estimate or based on the capacity of your plant. But then your sale is up and down and because of that, you end up with a pile of inventory. On the other hand, the pull system is where the production is done based on demand. And when I say based on demand, this demand could be from the customer or this demand could be from the next operation. So let’s understand this with some diagram here. So, what we have here in push system is we have three processes. Process A, process B and process C. Each of these can produce 100 items. Or let’s say we estimated that the demand is 100 items per day.

So what we do is we put 100 items through process A, then these 100 items go to process B C and we have 100 items as the final output. So this is a push system. You keep on pushing and you end up with 100 items. On the other hand, in pull system it is demand driven. So let’s put same process ABC here. So what we have is a customer. Let’s draw a customer here. Now customer demands something. So customer pulls the item from the finished product. So now the finished product has gone down by one number. Now, that creates a demand on process number C. Now, process number C has to produce something. So process number C expects B to produce.

So C asks B to produce something and B asks A to produce something. So now what’s happening is instead of V estimating the demand and producing something here, the customer is pulling the output from the value chain or from the production chain. So this is the difference between the pulse system and the push system. Now, what happens in pull system is since we are producing based on demand, so this limits the inventory and this also limits the items which are work in progress because whatever is being produced is being produced based on demand. So you don’t make something and store and sell here. You make only those things which are required to be produced. And for pool system we use a tool or a card to manage inventory. And this is called as Canvan.