In this chapter
▶ Merging Lean and Six Sigma to make Lean Six Sigma
▶ Undertaking DMAIC to make things better
▶ Reviewing what you do to do it better
Considering the key principles of Lean Six Sigma
Lean Six Sigma takes Lean and Six Sigma features and integrates them to form a magnificent seven set of principles. The seven principles of Lean Six Sigma are:
1. Focus on the customer
Focusing on the customer and the value-added concept is important because typically, only 10-15 percent of process steps add value and often represent only 1 percent of the total process time.
2. Identify and understand how the work gets done
The value stream describes all of the steps in your process. To understand this process properly, you must go to the Gemba. (The Japanese word Gemba means the place where the work gets done.) Process stapling(we will come back to this later) involves you spending time in the workplace to see how the work really gets done, not how you think it gets done or how you'd like it to be done.
3. Manage, improve and smooth the process flow
If possible, use single piece flow, moving away from batches, or at least reducing batch sizes. The concept of pull, not push, links to your understanding of the process and improving flow. And it can be an essential element in avoiding bottlenecks.
4. Remove non-value-adding steps and waste
The Japanese refer to waste as Muda; they describe two broad types and seven categories of waste. Nowadays, non-utilized talent is commonly included in the generic wastes, so it has eight wastes in some organizations. (See below figure) Removing non-value-added steps and waste is another vital element in improving flow and performance.
5. Manage by fact and reduce variation
Doing so helps you avoid jumping to conclusions and solutions. Using a control chart enables you to interpret the data correctly and understand the process variation.
6. Involve and equip the people in the process
Involving people is what has to be done if organizations are to be truly effective, like so many of the Lean Six Sigma principles, it requires different thinking if it's to happen. Therefore, Non-utilized talent is considered a waste.
7. Undertake improvement activity in a systematic way
In Six Sigma, DMAIC is used to improve existing processes, but the framework is equally applicable to Lean and, of course, Lean Six Sigma. Where a new process needs to be designed, the DMADV method is used.
Improving Existing Processes: Introducing DMAIC
DMAIC (Define, Measure, Analysis, Improvement, and Control) provides the framework to improve existing processes systematically.
In the Define phase, you describe what you think needs improving. In the Measure phase, you use facts and data to understand how your processes work and perform to describe the problem more effectively. Now you can analyze the situation by using facts and data to determine the root cause(s) of the problem. With the root cause identified, you can now move to improve phase, identify potential solutions, select the most valuable, and test or pilot it to validate your approach, using data where appropriate. You're then ready to implement the solution in the Control phase. In the control phase, you need to implement your solution, checking that your customers feel the difference in your performance.
One of the key outputs from the Define phase is a completed improvement charter. The improvement charter is an agreed document defining the purpose and goals of an improvement team.
The improvement charter contains the following key elements:
- A high-level business case explaining why undertaking the project is essential.
- A problem statement defining the issue to be resolved.
- A goal statement describing the objective of the project.
- The CTQs specifying the problem from the customer's perspective. Unless you already have the CTQs, there may not be known until the measure phase.
- Roles identifying the people involved in and around the project, expectations of them, and their responsibilities.
- Milestones summarizing the key steps and provisional dates for achieving the goal.
Depending on your project's nature, you may also need to use some other tools, such as the affinity and interrelationship diagram shown in the below figure. If your project is large and potentially complex, an affinity diagram prepares you for success. It can also aid you in developing your improvement charter. Affinity and interrelationship diagrams define your project and help the team really understand what's involved.
Affinity and interrelationship diagrams will likely be used at the beginning of a design project, where the DMADV method would be used rather than DMAIC.
The below figure shows the steps in the creation of an affinity diagram. The process works best if you use sticky notes and silently brainstorm ideas on an agreed issue statement; for example, 'what issues are involved in introducing Lean Six Sigma into your organization?'
When you create the diagrams, please follow these rules:
- Use one idea per sticky note.
- Write statements rather than questions.
- Write clearly.
- Don't write in upper case. (reading lower-case words is easier).
- Avoid one-word statements (your colleagues won't know what you mean).
- Include a noun and verb in each statement.
- Don't write an essay.
After everyone has finished writing their sticky notes, maintain the silence and place them on the wall, as shown in the first part of the affinity diagram. Move the notes into appropriate themes or clusters (see the middle one); you'll probably break the silence here. Finally, give each theme or cluster a title describing its content (see the final figure).
An interrelationship diagram identifies the key casual factors or drivers for your program or project by enabling you to understand the relationships between the themes or clusters. In looking at the different pairs of clusters, you're trying to see if a cause and effect type of relationship exists, so does 'this' have to be done before 'that', or does 'this' drive 'that'.
The finished diagram can be presented as shown in the below figure, and you can clearly see the key driver is A, whereas E is probably the outcome of the project. It would help if you focused on A to ensure your project or program is successful particularly.
Throughout your project, developing a storyboard summary of the key decisions and outputs helps you review progress and share what you've learned. A storyboard builds up as you work your way through your project by capturing the key outputs and findings from the DMAIC phases. A storyboard would include, for example, your improvement charter and process map.
Measuring how the work is done
After you've defined the problem, at least based on your current understanding, you need to clarify how, and how well, the work gets done.
Measure what's important to the customer, and also remember to measure what the customer sees. Gathering this information can help focus your improvement efforts and prevent you from going off in the wrong direction. Using control charts can help you make better sense of the data.
Use the CTQs as the basis for getting the right process measures in place.
Analyzing your process
In the measure phase, you discovered what's really happening in your process. Now you need to identify why it's happening and determine the root cause. It would help if you managed by fact, though, so you must verify and validate your ideas about possible suspects.
Carrying out the Analyse phase properly helps you determine the solution when you get to the improve phase.
In checking the vital view, you may find the usual suspect aren't guilty at all! Identifying and removing the root causes of a problem prevents it from happening again.
Improving your process
Most people want to start at this point. However, the preceding steps help you land in the correct direction where you should start the improvement. Improve, however, involves three distinct phases:
1. Generate ideas about possible solutions.
2. Select the most appropriate solution.
3. Plan and test the solution.
Coming up with a control plan
If you're to contribute your efforts in reducing variation and cutting out waste, the changes being made to the process need to be consistently deployed and followed.
If the improvement team is handling over the 'new' process to the process team, the handover needs to ensure that everyone understands who's responsible for what and when. A control plan needs to be developed to ensure that the gain is secured and the new process effectively deployed. (please see the below figure showing general contents in a control plan)
The control plan helps to ensure that the process is carried out consistently. It also identifies key points in the process where measurement data is needed, plus highlights what action is needed depending on the results. Ensuring you have the right ongoing measures in place is extremely important. You can also find the example of a control plan.
Reviewing your DMAIC phases
Informal review of your improvement project's progress on a weekly or even daily basis may be very sensible. These reviews involve the improvement team and the champion or sponsor.
But, as a minimum, you should conduct a formal tollgate review at the end of each DMAIC phase. A tollgate review checks that you have completed the current phase properly and reviews the team's various outputs from it.
Before moving from one phase to another, stepping back, assessing progress, and asking some key questions is crucial. For example:
- How are things going? For instance, is the team working well together?
- Are we on course?
- What have we discovered?
- What went well? why?
- What conclusions can we draw?
At the end of the Analyse phase, the review is of particular importance. It provides an opportunity to review the scope of your project. By the end of this phase, you should quantify the opportunity- to really understand the extent of non-value-adding activities and waste and the potential for improvement. On completion of the Measure phase, you can understand the current situation and level of performance. Following the Analyse phase, your level of understanding will have increased significantly, and you'll understand the root cause of the problem:
- You know why performance is at the level it is.
- You understand the costs involved in the process, both overall and at the individual step level.
- You have identified the waste and the non-value-adding steps, including the extent of rework and understanding their impact on your ability to meet the CTQs.
As with quantifying the opportunity, the post-improve review also provides an opportunity to look at the project more generally, and key questions include:
- Are we on course?
- What have we discovered? And forgotten?
- What went well? Why?
- Can we apply the solution elsewhere?
- What conclusion can we draw?
Management by fact is a key principle of Lean Six Sigma, so you should have appropriate measurement data and feel confident about what your solution will deliver.
Quite a range of different benefits may occur, including:
- Reduced errors and waste
- Faster cycle time
- Improved customer satisfaction
- Reduced cost
A third and final benefit review follows the Control phase, enabling you to confirm the actual costs and benefits and whether any unexpected debits or credits have occurred. And you should know the answers to their questions:
- Do our customers feel an improvement has occurred? How do we know?
- Can we take any of the ideas or 'best practices and apply them elsewhere in the business?
Maintaining an up-to-date storyboard as you work your way through the DMAIC phases helps you prepare for the reviews and share discoveries.
Taking a Pragmatic Approach
Some have criticized Six Sigma and DMAIC for being too complex and for projects taking too long. Be pragmatic. Projects need to take as long as is appropriate, and often only a few simple tools and techniques are needed to secure quick and successful improvements.
Some say that Lean doesn't always ensure a systematic and controlled approach to achieving and holding on to improvement gains- this is where the Control phase of DMAIC is so important. For relatively straightforward problems, rapid improvement events can be utilized. There can be run in one-week sessions- sometimes known as Kaizen Blitz events.
Rapid improvement events can also be run as a series of half or one-day workshops over a period of five or six weeks. They follow the DMAIC framework; particular emphasis is placed on the Define and Control phases.
※ 참조: 본문은 책, "Dummy들을 위한 린 식스시그마(Lean Six Sigma)"와 The Toyota way를 정리한 내용을 기반으로 한 글입니다. 현재는 원서 내용을 정리하고 있는 중이며, 정리가 완료되면 한글로 번역을 추가할 예정입니다.
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