ASQ CQA – 5. Quality Tools and Techniques Part 5

10. 5A9 Plan-Do-Check-Act (PDCA) Cycle

Coming to this last tool in the list of basic quality and problem solving tools, which is PDCA or plan, do, check, act, p than a tool. I will consider this as a philosophy. A philosophy for doing anything. So whatever you are doing, doing, you do this, you plan, you do, you check and then you act on that. So when we talk of PDCA cycle, there are two names here. PDCA plan, do, check and act, and PDSA plan, do, study and act. Initially, Dr. Schwartz originated PDSA cycle, which was plan do study act. When Damming went to Japan, Damming promoted that cycle which was PDSA for quality improvement. And later on Deming changed that name from PDSA to PDCA cycle.

And why do we use PDCA cycle? Because PDCA cycle is a continuous improvement approach. So if you look here, here I have those two cycles, PDSA and PDCA. To understand this, let’s take example of me preparing this course, which is this CQA exam preparation course. The first thing which I need to do is plan for this.

I need to plan the curriculum, I need to plan the lessons, I need to plan how much inputs I will have, how much details I will have in each of these lessons. So this was the planning part. Then what I do is I do that in doing, I make PowerPoint slides, I make these recordings. And then I do editing of these. So this is the doing part. So I planned, I did. And then what I do is I check. I check all these final deliverables, which are the videos to see whether everything is fine or not.

So this is checking part. And then during the checking, if I find out that in some of the videos the sound is low, or in some of the videos there is lot of disturbance, then I need to act on that act to make any changes. So this is a PDCA cycle. Then this cycle keeps on repeating. Now, once I launch this course, then I will get students feedback. Some of the students will give me feedback that this lesson is good, this lesson is not good, whatever it is. Then based on that feedback, I again need to plan changes to my course. So I again plan that okay, I need to add some extra lesson. Or I need to have this thing explained in more detail. That’s the second time I plan.

And then I do that. I make those changes, I check everything is fine. And then I act on any mistake if I find. And this cycle keeps on repeating. I keeps on getting feedback, I keep on planning, doing, checking and acting. So this is PDC Cycle. This could apply in any field. So whatever you are doing, you plan. First you do and then you check or study whatever you want to say. And then you act on that. The outcome of your study or the outcome of your checking, you act on that. So this was the 9th Tool, which is PDCA cycle. So with this we have completed the basic quality and problem solving tools which was section five A of the CQA body of knowledge.

11. 5B1 Six Sigma

Section five of the CQA body of knowledge is quality tools and techniques. In that previously we talked about five A, which was basic quality and problem solving tools. In that we looked at nine basic quality tools. Now we come to five B which is process improvement techniques. In process improvement techniques we will be talking about two process improvement techniques and these are Six Sigma and lean. Let’s talk about Six Sigma here in this video. And then in next few videos we will be talking about number of lean tools. Let’s come back to Six Sigma. In Six Sigma we will be talking about the history of Six Sigma. I will explain Six Sigma in layman’s term. And then we will be looking at three approaches. For Six Sigma. The next thing will be defect level and sigma number. And then we will talk about DMAC and DMAD V approaches. And then we will talk about Six Sigma belts such as white belt, yellow belt, green belt, black belt. What do they do? So this is the lesson plan for Six Sigma. Six Sigma in itself is a big topic. And as I earlier talked, there are a number of belts.

White belt, yellow belt, green belt, and black belt. So as you go through these belts, you learn more and more about Six Sigma. There’s a lot of complexity, there’s a lot of mathematics and statistics involved in Six Sigma. So if you want to learn this in more detail, then you can go through these belts. But let’s focus on CQA body of knowledge. In CQA Body of Knowledge, you just need to have a high level understanding of Six Sigma. And that’s what we will be doing in this lecture. Let’s start with a quick history of Six Sigma. When it comes to the history of Six Sigma, few things which you need to remember for your exam is that Six Sigma was invented by Motorola in 1987. And then another company which is associated with Six Sigma is General Electric. General Electric implemented six sigma in a big way. They implemented Six Sigma in all the processes, all the work they did, all the managers in General Electric were required to go through Six Sigma training and implement that. So these are two main things in the history which you need to remember. Motorola invented that and General Electric implemented Six Sigma in a big way.

Now after talking about this quick history, now let’s understand what Six Sigma is. So to understand Six Sigma, let’s take an example of a plane aeroplane, which is landing on the strip. So for plane to be safe, the plane has to land on the landing strip. You don’t want the plane to land outside the landing strip. So this is what you expect normally. But when we talk of Six Sigma, our intention is that the pilot should be able to land the plane in half the width of the landing strip. Most of the time not using the full width, just the half of the width. If the pilot is able to land the plane in half of the width of the landing strip, then we will say that pilot has Six Sigma performance. So now, if I generalize this concept, what does Six Sigma mean? Is that whatever tolerance you have, you just need to use half of that tolerance. If you are using half of the tolerance, then you are having a Six Sigma performance.

So if you need to make a piece which is having a size between 101 two, if this is the tolerance, then you will have Six Sigma performance. If most of your pieces are not between 100 and 102, but between 100. 5 to 10 1. 5. So here what you are doing is you are using 1 mm talent instead of two millimeter tolerance allowed to you. So this is what Six Sigma is. In layman’s term, there are three broad approaches of implementing Six Sigma and these approaches are using Six Sigma as a statistical tool or using Six Sigma as a process, or using Six Sigma as a philosophy. Let’s talk about Six Sigma as a statistical tool. So when you are implementing Six Sigma as a statistical tool, what you are looking for is less than 3. 4 defects per million. But in more technical terms, this is 3. 4 defects per million opportunities. This is another thing which you need to remember for your exam as well. Six Sigma performance means 3. 4 defects per million opportunities. Let me put it here 3. 4 defects per million opportunities. When you want to use Six Sigma as a process here what you are interested is in improving processes in that we have two approaches DMAC and DMADV.

We will talk about these, but let me put it here. One is DMAC and the second approach is DMADV. So this is how you use Six Sigma as a process. The next one or the highest level of implementing Six Sigma is using Six Sigma as a philosophy. Here organizations understand that anything less than ideal has an opportunity to improve. So wherever there is a possibility, you improve that. If you work with that mindset. If you implement Six Sigma with that mindset, then you can say that you are implementing Six Sigma as a philosophy, improving anything and everything which is not ideal. General Electric implemented Six Sigma as a philosophy. Most of the organizations implement Six Sigma either as a statistical tool or as a process improvement tool.

So previously when we were talking about using Six Sigma as a statistical tool, we said that Six Sigma means 3. 4 defects per million opportunities. We are not going into the mathematics of that. But let’s look at the table here. When you have 3. 4 defects per million opportunities, that means you are having Six Sigma performance. And as your defect level or defects per million opportunities go up your Sigma level, keep on reducing. When you have 500,000 defects per million opportunities, then you are having 1. 5 sigma. And 500,000 per million means half. If half of your items are getting rejected, then you can say that you are having 1. 5 sigma performance level. So this table gives you the correlation between the sigma level and the defect level. And same thing you can see on the right side here in form of a graph, as sigma level goes up, the defect level goes down.

Other thing which we talked earlier was that using Six Sigma as a process improvement tool there we talked about two approaches DMAC and DMAC V. Let’s look at these. So, here we have DMAC approach. DMAC approach for process improvement is used when you want to improve an existing process. So if your existing process is not giving the desired results, then you use DMAC approach to improve that process. Your existing process might be giving too many defects. Your existing process might not be satisfying clients needs. Whatever case might be. When you want to improve that existing process, you use DMAC approach. And DMAC stands for D for define, m for measure, A for analyze, I for Improve, and C for control. So the first thing is defining the problem, what problem you have? My weld repair rate is high, my customer satisfaction level is low.

Then you measure that measure in terms of what is the percent defective in case of welding, what is the satisfaction level of the client that you measure. Once you have measured that, then you analyze those measurements. In analysis, you look at the root cause. You might use some of the tools which we talked earlier such as Fishbone diagram, histogram parattochart. You could use even those simple tools, or you could use even more complex tools which are taught in Six Sigma courses. But then you analyze the problem and then you improve. You improve the existing process. And once you have improved the existing process, the last step is C. C stands for control. Here you want to control your process in that new improved level. You don’t want your improved process to fall to your original level. So for that, you need to put some controls in place.

So, this is the DMAC approach for improving an existing process. But if you are designing a new process, the approach for that is DMAD V. DMADV stands for D for Define, m for measure, A for analyze. So these three things are same as in DMAD. But then the next two stages are design and verify. So this is something which you use when you are improving a new process. This is also called as DFSS design for Six Sigma. Now coming to Six Sigma Belts. As I earlier told, in Six Sigma you have a white belt, yellow belt, green belt and black belt. So these are the level of competency. So you start with white belt. White belt is for management level or for people who just want to have some basic understanding of Six Sigma, then you move to the Yellow belt.

Yellow Belt is the beginner level belt. Here you participate in a Six Sigma improvement team. So if you have qualified as Six Sigma Yellow Belt, you become part of Six Sigma team as a team member, and you support those projects. Once you go to Green Belt, you acquire more knowledge, you acquire more experience. Then in Green Belt, you either lead some small sized projects, the projects with less complexity, or you could support the black belt in executing a complex project. Green Belt is a part time assignment. Here you keep on working on your existing work, whatever you are doing. So if you are in assembly, if you are in design, you keep on doing that job.

But in between you support Six Sigma projects on part time basis. The next level is black belt. Black Belt is a full time job. So once you are a black belt in your organization, the only thing you do is Six Sigma improvement projects. You lead complex projects, complex improvement projects, and you even mentor green belts so that they can improve and they can also become black belt someday. So these are four main levels, but then on top of that is Master Black Belt. The Master Black Belt is someone who is very competent in Six Sigma and project management. Generally, you will have one person as a Master Black Belt in the organization who will train black belts and other belts. So these are the belts in Six Sigma.