I have nothing against six sigma per se. We used it at Danaher, Wiremold, and many other companies I was involved with in the private equity business. And while there are undoubtedly many ways to think about six sigma, I have always thought of it as a form of statistical process control (SPC), which is invaluable for finding and smoothing out variation in processes. I found SPC particularly helpful when dealing with very tight tolerances or processes with multiple inputs like temperature, flow, or time, where you couldn’t really see what was going on.
SPC was helpful to me when I was a group executive at the Danaher Corporation. We used it at Jake Brake (one of my group companies that made engine retarders for diesel trucks) when it had problems holding tolerance on parts coming off its screw machines. This lack of control created many rejects when we tried to assemble the final engine brake, which in turn was causing many defects. So, we decided to use SPC to try to eliminate the problem.
Soon after starting our SPC experiment, we started working with the Shingijutsu consultants from Japan. Specifically, my colleagues and I worked with three former Toyota executives who had spent their careers at Toyota, the last ten years working directly for Taiichi Ohno, the father of the Toyota Production System. They looked at what we were doing with SPC, kind of laughed, and just said “no” — as in “no good.” When we asked them why, they wouldn’t tell us, indicating that we would not understand, so why should they waste their breath.
… what alarmed me was seeing companies use six sigma as their primary cost-reduction approach — and, in fact, a core part of their strategy.
Instead, they showed us how to approach the tolerance problem from the lean point of view, which involved rethinking virtually every assumption we had made about how to do the work and improving the complete system rather than chasing down “point optimization,” or random improvements. We learned that controlling the setup and having fixed stops to maintain the tolerances and 100% inspection before a piece could move forward eliminated the problems. This approach also eliminated all the work we were doing to collect and analyze all the data, which was nothing but extra expense and therefore waste. We, in effect, eliminated the problem at the source.
Addressing this tolerance problem was a great learning experience. As I became more immersed in lean over my career, it became clear that occasionally using SPC could be helpful. However, what alarmed me was seeing companies use six sigma as their primary cost-reduction approach — and, in fact, a core part of their strategy.
Understanding the Limitations of Six Sigma
After I left General Electric to join Danaher, CEO Jack Welch got on the six sigma train in such a big way that it became almost a religion. And, of course, if Jack thought it was a smart thing to do, it wasn’t long before many other companies copied GE. I always thought this was a huge mistake for GE and a waste of their tremendously talented workforce.
The problem is that while you can realize some gains (admittedly, sometimes significant gains) from six sigma, this approach only goes after 10% to 20% of what is possible. That means you can have thousands of successful six sigma projects to brag about without much effect on the bottom line.
… while the six sigma approach fixed one of 20 steps, the lean approach addressed them all and delivered a lot more value to the customer.
Why? Let’s say you have a product line that has 20 value-added steps. Maybe one of the steps is a bit of a bottleneck, making it a perfect candidate for a six sigma team. You then focus exclusively on this step. Because you have smart people, you will improve this process and have a great six sigma story to share. Nice, but what about the other 19 steps? You still have those. They may be in different functional departments, but they still exist. So, on balance, you didn’t get all that much gain.
On the other hand, if you approach this with a lean mindset, you will look at all 20 steps from the beginning. First, you will take them out of their functional departments and line them up next to each other in a one-piece flow line. Then, you will look at the takt time, which will, in turn, help you see the waste in all 20 processes. As you improve each step, you will get enormous gains in productivity, quality, scrap reduction, lead time reduction, and customer service. So, while the six sigma approach fixed one of 20 steps, the lean approach addressed them all and delivered a lot more value to the customer.
Choosing the Easy Way or the Best Way
So why not just use the lean approach? You would think folks would want to run their businesses in this proven superior way. The answer is that lean requires a drastic change from the traditional way of running a business while six sigma does not. In the example I just cited, the lean team would go into the functional departments and rearrange all 20 machines into a one-piece flow line. This type of radical change is terrifying for the traditional manager. These machines haven’t moved since they came into the plant 15 to 20 years ago. Moving them will be disruptive and cost a little money.
And then, of course, there is the universal question, “But what if this doesn’t work?” Simply seeking six sigma gains involves none of these tough challenges. Everything can stay essentially the same, and the six sigma team can just work on the bottleneck process in the functional department where it lives. There is no disruption, no moving costs, and no worries about it not working. Six sigma, for most companies, is the hands-down choice. Whew, they avoided that lean nonsense.
So why not just use the lean approach? … The answer is that lean requires a drastic change from the traditional way of running a business while six sigma does not.
Six sigma also fits much better with the safe, studied way traditional companies solve problems. When faced with any serious issue to consider, most companies form a team that will meet once per week to study the situation and develop a plan. This team usually is a group of salaried employees who gather and analyze data. (You can easily see how a group of salaried six sigma experts could be the team members in this case.) Because not everyone can make every meeting, it might take two to three months to come up with and agree on a plan. Great. Now management has to approve this plan — another month.
The lean approach is quite different. It will also start by forming a team — but one comprised equally of hourly and salaried employees who will be taken off their full-time jobs for one week and given a very aggressive set of targets to meet by the end of the week. For example, they might start moving equipment by the afternoon of the first day. As a result, they will have a new line up and running by the end of the week with greater than 50% reductions in floor space, inventory, staffing, defects, and lead time.
Evaluating the Value of ‘Belt’ Certifications
And, what about black belts and green belts and yellow belts? Aren’t they important? My response is, “Look, you’re running a business not a karate class,” which always shocks people — maybe because it’s true. Companies spend a lot of time and money (up to several years) training a small select group of salaried employees to do SPC. Usually, they participate in six sigma study teams and then just return to their regular job. They may receive a nice certificate and a colored belt, but after all the training time, cost, and awards ceremony, they rarely end up doing six sigma full time. I prefer the lean approach of forming a Kaizen Promotion Office (KPO) staffed with your highest potential employees. Their full-time job is organizing, running, and following up on kaizen events. They learn lean by doing lean in a hands-on approach under the mentorship of an outside lean sensei. A good rule of thumb is to keep them in the KPO full time for about two years and then move them on.
‘Look, you’re running a business not a karate class.’
Six sigma enthusiasts have told me black and green belts are important ways to recognize the extra training given to their selected salaried employees. OK, I get the idea, but what about just promoting them? We pushed our best and brightest through the KPO so that they could become lean experts. Then, after two years, we promoted them to run something, like team leader, plant manager, or something else. That always seemed more important to our business than giving them a certificate and a belt they could keep in the drawer.
I’m sure I’ll get some negative feedback for this Ask Art. That’s OK. I’m just trying to point out that six sigma is comfortable because not much has to change with it. But unfortunately, that includes your results. On the other hand, adopting lean is very uncomfortable — until you see the results. You choose.
Completely agree with your POV! Its exactly why I chose to pursue the Lean Expert path instead of the Six Sigma BlackBelt path several years back at Honeywell. I did get a Six Sigma GreenBelt but found Lean to be a lot more impactful and long lasting. Plus Lean can be applied everywhere IMO – at work and also at home!
So inspiring this article, Art.
I had and I have strong discussions on these point: Six sigma and colored belt. They look cool and you described very well the reasons why.
Fortunately I’m working in a company with the KPO with people dedicated to do improving and kaizen events, but still the top management and the departments not directly connected with operations consider us good to do reduction cost but not for the big changing.
We are working on it, both increasing the capacity to use the hands-on approach by the most part of people in production area (they have not to wiat the lean expert!), and involving more and more the other departments in lean activities
Great comments on the practical differences between Lean and Six Sigma. In my past, I was designated as the “Corporate SPC Champion” and earned a SS Black Belt. I agree with your comments. Although SPC can be used as a problem alert tool, it does not solve problems.
I have often asked hire candidates (and others) “What is the difference between Lean and Six Sigma?”. My favorite response was: “Lean is for everyone, Six Sigma is for the ties”. In my mind, we want a company full of people working on problems instead of just engineers schooled in a methodology that is not focused on speed.
My position has evolved over the years and has settled in on this: As we transform our company, we are “Leading with Lean”. There are many valid tools and methodologies but Lean is the only one that: 1. Involves everyone, 2. is Industry Agnostic, 3. focuses on Customer Value, 4. Eliminates Waste, 5. Eliminates Variation and 6. Improves Through-put rates
Thank you for putting these thoughts in such a clear presentation of a sometimes unclear topic!
Phil, thank you for your comments and excellent additions to the post. Your comment “Lean is for everyone and Six Sigma is for the ties” is just perfect. It is my whole article in a nutshell.
I believe you could write another article on the following quote, “A good rule of thumb is to keep them in the KPO full time for about two years and then move them on.”
While I understand this strategy might support getting more of the workforce exposed to lean and may help the organization shift the mindset/culture towards lean principles through personal experience, I wonder if a transient KPO workforce might present some limiting factors, as well.
For example, how does the two year turnover affect the stability of the office and/or the value streams that receive their support? How does this turnover affect the KPO’s internal culture?
Does this affect senior leaders’ level of TRUST in the KPO’s ability to lead their lean journey? In my experience, Gemba members need to trust the process AND trust that their KPO member is well-versed in lean principles/A3 thinking, or at least know when to pull on their sensei for additional support. If a value stream’s improvement plan spans longer than two years, do they adjust well to the changing KPO support when the new individual starts their KPO onboarding?
I’m also interested to hear if this (assumedly) guaranteed path to a promotion affects the overall workforce’s perspective on the KPO? Do they look at it as a quick stepping stone, or a valuable experience that’ll set them up to lead their organization’s lean journey? Does it attract the right people for the right reasons?
I could go on 🙂
Thanks for considering.
Luke, yikes! I think you are making a mountain out of a mole hill here, no offense. We never tried to examine the KPO like this. If we had we might have been able to talk ourselves right out of having one as you seem to be trying to do. We created the KPO to make sure we had on site lean experts that could run and follow up on kaizens everyday. We also wanted to broaden the number of people across our organization that had strong lean skills and experience. It was learn by doing for the KPO just like the entire rest of the company. No one expected them to be the second coming of Taiichi Ohno. Plus we had our outside Japanese consultants with us for one week every month to tackle tougher projects and train the KPO. People rotated in and out of the KPO one by one not like a single class so there was no problem with stability or the KPO’s internal culture. As for your question of wether senior leaders trusted the KPO’s ability to lead the lean journey that was never an issue as I expected the senior leaders to lead the lean transition and insisted that they each be on 5-6 full week kaizens each year. They had to learn by doing as well. The other key thing that you are missing is the half of the people on everyone of our kaizen teams were hourly associates who did the work in the area we were trying to improve. All the best ideas came from them. I’ll leave you with one last thought, I’m sure glad you never worked for me!
Art, I find the SPC example very intriguing. Especially when you mentionned that, at the time, you did not know “why” it was not the right approach to your problem.
I would like to try an explanation on the “why” since I could not really find it in the story.
My understanding is that your process had too much “normal cause” variability and this is why you “had problems holding tolerance on parts”.
In such a situation, using SPC is in fact not the best approach since the goal of SPC is to identify and eliminate “special cause” variation. However, when a process’ “normal variation” is too large, we need to study and change the process… and this is what your coaches lead you to do by “rethinking virtually every assumption you had made about how to do the work and improving the complete system rather than chasing down “point optimization””.
I guess you can call this a Lean or a Six Sigma approach… does it really matter? I would rather call this: “Going back to Deming’s teaching about how to approach variability”.
Martin, thanks for your comments. Of course you are right when it involves my example of problems with our screw machines not holding tolerance. Either lean or six sigma could have solved the problem although I think six sigma would have taken longer and may not have resulted in as permanent a solution as we got with lean. But what if there were no real problems just a bunch of built in waste in every process? Would six sigma be the right approach to create flow? To reduce set up time? To create visual control? To get all of our hourly associates involved in removing waste? I’m not opposed to six sigma at all. I just think it should not be used as your strategy or primary problem solving approach.
Hello Mr. Byrne,
As Mr. Irani stated…I am a huge admirer of yours also, and highly respect the work you have completed and your contributions to the continuous improvement world! They have been immense!
I was sad, however, to read of your clearly unfortunate experiences with one of the best problem solving and process improvement methodologies ever developed, Six Sigma.
Six Sigma, when the system is correctly deployed (which is the root cause of most deployment’s failure) is just as powerful as a successful implementation of a Lean production system.
I had the great pleasure of being involved in the tremendously successful deployment of Six Sigma while employed at AlliedSignal in the 1990’s. Larry Bossidy was the CEO at this time (who, by the way, convinced Jack Welch to implement Six Sigma at GE).
During this period, AlliedSignal also implemented Lean, Business Process Management, and the Theory of Constraints. Hoshin Planning was in the mix too (we also learned TOC directly from Goldratt, and how to lead Kaizen events directly from Sensei’s from Japan) So, it wasn’t just a single “religion” being deployed, but Bossidy helped us lead with Six Sigma as the primary cultural change component that truly changed the way AlliedSignal worked.
We had hundreds of belts to help embed continuous improvement thinking into the culture, and there was not sub optimization of the system, as we implemented continuous improvement through belt projects, kaizen events, and targeted use of TOC. We ultimately came to call our deployment “Six Sigma Plus.” After AlliedSignal purchased Honeywell, and kept the Honeywell name, all of this has matured into the “Honeywell Operating System.” (HOS). This operating system is continuing to help Honeywell achieve value (Six Sigma is not about just cutting costs…reference deployment errors above) for their customers.
I left Honeywell in 2003, and have worked for several companies that tried to implement Six Sigma….and Lean, and Business Process Management and all of these have had limited success. In all cases, these attempts have just not been effectively deployed.
Six Sigma, Lean, Theory of Constraints, Business Process Management should be used in a coordinated and complementary fashion, and when deployed correctly, can lead to much great success than beating the drum of one individual religion.
So, as I began, I was sad to read of your unfortunate experiences with Six Sigma, but let’s not drag this wonderful problem solving and process improvement methodology through the mud, as a result of not being effectively deployed.
All the best to you….
Paul, thanks for your input. I learned a lot from your comments. I’m sorry you got the impression I was trying to drag six sigma through the mud. That was not the case as six sigma helped us solve a lot of difficult problems on our lean journey so I am a believer. I was just trying to say that using six sigma alone as your strategy or main problem solving tool is not as good an approach as lean. Years ago we had the entire management team of Allied Signal’s aerospace business come to visit us at Wiremold for a couple of days when they were just starting their lean journey. A few years later I ran into one of their senior people on an airplane. “How’s the lean implementation going?, I asked. He said well we were doing great until Bossidy arrived and started six sigma. Now we have lots of projects going on but little effect on the overall business as we are not looking at the whole process. I was impressed that he understood that. I’m not knocking Larry Bossidy by the way. During my second General Managers job at GE he was my ultimate boss and I always thought he was smarter than Jack Welch. At the same time I thought Jack’s embrace of six sigma was a big waste of time for GE and that if they had started lean instead they wouldn’t be the mess they are today.
Even so, I was glad to hear that Allied Signal/Honeywell eventually added lean and other approaches and were very successful. I would guess the Bossidy’s leadership also had a lot to do with it. I would call that a great lean story while you would say it was a six sigma success. Sometimes its just semantics. Just remember the point of my post was not to drag six sigma through the mud.
Great article with many good points. However I have to disagree overall. When I went through my formal process improvement training in 2003 it was Lean Six Sigma; not one or the other but how to join the two approaches in a complimentary way. Maybe I was lucky that at that time, my training was not “just” six sigma but how to leverage both methodologies for a more holistic approach.
I agree with your comments. Why not “and” instead of “or”? Lean and Sic Sigma and TOC and … instead of “or”. We can learn something from them all.
Scott, thanks for your input. I’m glad your training involved both lean and six sigma. I saw that happen with a lot of companies that started out with six sigma but eventually evolved to lean as the main approach because it was delivering better results. They didn’t really want to discredit six sigma so they just called it lean six sigma. Nothing wrong with that. What you do and what you call it can be totally different. You seem to have gotten the best of both worlds. I wasn’t trying to suggest in my post that it was an either or choice. Our main focus was on lean but we used six sigma a lot where it made sense.
I combine Lean and Six Sigma when training on how to perform improvements. We follow the 5 steps of DMAIC while using the appropriate lean tools for each phase. I have always found that the two marry well together. As someone who trained and received my Black Belt at a world class Lean company, I also respect the hard work and the Belt earned. To say Belts don’t matter would also be like saying you go to get your degree but once you have studied and learned it, they tell you you don’t get the degree – just be happy with the knowledge. Or you compete in the Olympics and win a medal but we aren’t going to award you that medal. Just be happy knowing you won.
Tamera, I’m sorry if I offended you. If you learned lean and six sigma at the same time great. My comments were aimed at companies that just train six sigma, award black belts but then don’t employ that knowledge full time. Instead people just go back to their regular job and may get called on from time to time to lead an improvement effort. I think this is wasteful. If you put in the effort to learn lean and six sigma we should let you do it full time and it should eventually lead to promotions for you so you can spread the word and teach others. Congratulations on your black belt.
Hi Mr. Byrne:
I am a huge admirer of yours. Love both your books. But …..
Would you be familiar with what Industrial Engineers do? I think that TPS itself is Industrial Engineering by a different name! Anything that you say is Lean, I could point to something similar or identical discussed in one or other IE textbook. Anything that you say is Six Sigma, I could point to something similar or identical discussed in one or other IE textbook. Else, I would simply accept that new knowledge into the IE BoK.
An IE designs systems, evaluate processes, etc. We are not dogmatic about whether what we do is Lean or Six Sigma or Lean Six Sigma. We simply find and use the tool or software or technology that works to solve the IE problem that we encounter.
So what if we buried Lean and Six Sigma and Lean Six Sigma? Instead, we focused on improving the education and training of the Industrial Engineers of today and tomorrow. And to do this, we assimilate into IE the relevant subject matter from Lean and Six Sigma.
Most of all, what if we infused into the TPS the science, analytics and software that IEs use? The TPS is a very limited and limiting production system. For example, in this day and age, using Value Stream Mapping (or Material and Information Flow Diagrams) to design a manufacturing system is cumbersome. Simulation would provide much better guidance to the design team.
I would love to hear your comments.
Dr. Irani, thanks for your nice comments. I’m glad that you enjoyed my books. I agree with your comments that both six sigma and TPS have their roots in industrial engineering. In fact I could even agree if you just wanted to call them nothing but industrial engineering. But you seem to be coming at this from a very academic and traditional point of view where the IE department designs the processes from their ivory tower and then implements them on the shop floor. In essence you are doing something to the workers not with the workers.
I’m sure you would be shocked to learn that at Wiremold I got rid of the IE department and the ME department and just assigned those engineers to value stream teams out on the shop floor. We wanted them to get their hands dirty at least five times a day while helping to remove the waste from our processes. They loved it by the way. At the same time I was increasing our hiring of bright young IE’s and ME’s as we needed their training and brains to move to the next step. We found this worked best when they worked with our hourly associates and incorporated their ideas as they were the ones that knew where all the waste was. Mostly it was in our existing processes designed by our former IE department.
Here is an example for you to think about. A number of years ago the CEO of Milwaukee Electric Tools asked me to come help him. I ran a couple of kaizens for him. One of the first projects was the first cell that they had created on their own and had just started working the week before. They had taken four of their young IEs and put them to work for three or four months designing this new cell. They were very proud of it and I was surprised that they would allow it to the subject of a kaizen. Anyway, by the end of the week we had gotten reductions of 50% to 90% in just about everything, man power, space, inventory, through put time, walking distance, change over time, etc. The IEs were kind of blown away by this but to their credit they just said, “If I hadn’t been on this team I would never believe this was possible.” Now how could this happen? After all I was leading this team and I am not an IE I’m just a lowly businessman.
The key of course is we worked with the operators on the floor and made all the changes that they pointed out.
Don’t miss understand. I’m not knocking IEs at all. I always wanted more of them. But when we ran kaizen teams on the floor to design new processes half the team was hourly employees and usually they came up with the best ideas assisted by the IEs. Now sure, if you are designing a new petro chemical plant from scratch your hourly work force might not be that much help. Even so getting the IEs input from people who worked on the floor of the old plant could really help with the design.
Please don’t take this the wrong way I really enjoyed your input.
100% in agreement with your article. It’s better to get into action and have short learning cycles from the beginning, and of course use SPC but only when is necessary.
When one is involved in the world of improvement, one must have a toolbox to know which one to use for any problem presented. lean and six sigma are means to achieve organizational objectives, there is no comparison to determine which is better or worse.
The culture of change is adopted by the organization through objectives that challenge all its processes, the next step is to define how you will achieve it, what tools you will use.
Israel, you need to get beyond the “tools” stage of improvement. If you stay stuck there then you can make your argument that you can’t determine which is better lean tools or six sigma. To really improve you have to change the culture not just dabble in tools here and there. I refer you to a recent lean post of mine on how to create a lean culture. Art.
Art, you are correct.
Our elite six sigma team “swooped in”, determined a new course of action (without asking any of us – line Mgrs/production team) then they leave and all Leadership is surprised when no miracle occurred.
My take is the six sigma team had no skin in the game so very little responsibility on their part.
Using Lean with SPC (when appropriate) is the better choice. We proved this many times a couple of years later.
Always look forward to your articles.
Perry, I’m glad you enjoyed the post. Your example was a nice add as it is very typical of a six sigma focused approach. The black belts and green belts swoop in then go away and not much change really happens. Art.
Although I started my continuous improvement and operations excellence journey as a Six Sigma black belt, I actually agree with Art on this.
Once we adapted Lean as the foundation for our operations excellence initiative, we gain so much more as a business.
However, we kept some foundational Six Sigma concepts for structured problem solving and the use of data to guide the process.
Stefano, thanks for the nice example. If you focus on lean and just use six sigma where appropriate you will make much more progress. Art.
Thank you Art for making this clear distinction. I played both roles, black belt and KPO, so I lived the differences exactly as you mentioned.
I would just add the political dimension to the six sigma world:
I was working for a particular company as a technical expert and successfully implemented a technical change that saved an important amount to the bottom line. I worked with the line people in making all the required changes, not having any kind of six sigma training. Just imagine my surprise when the plant manager told me that the project is going to be advertized as a six sigma project to corporate … this happened after all the work was done.
Ovi, thanks for your comment and congratulations on your wonderful new book. Your right, politics can unfortunately play a big role in how an organization thinks. I have seen many other examples where the CEO declares six sigma as the way forward and as a result all improvements whether from a lean kaizen or just some traditional cost cutting has to be declared as a “six sigma success.” Stay clear of those kind of companies. Art.
Art, thank you for being an inspiration!
Art, you’re right. I got my green belt certificate years ago, and I used the knowledge just in few cases.
But in recent years I see the same risk with lean… there are a lot of courses on lean tools, and there are a lot of experts on A3 or value sream map. But this is not lean-
Francisco, you are correct. If you just see lean as a bunch of tools that you can pull out at will things won’t be much different from your experience as a green belt. Unfortunately that is the norm for most companies. Lean is seen as just some cost reduction approach as opposed to the incredible strategic weapon that it really is. I refer you to one of my recent lean posts on how to create a lean culture to see what is really involved. Art.